JP6000083B2 - Exhaust gas denitration system - Google Patents

Description

  The present invention relates to an exhaust gas denitration system.

  Conventionally, a laser gas analyzer is known as an apparatus for measuring the concentration of a specific substance contained in a gas mixture. This laser analyzer utilizes the characteristic that each gaseous gas molecule has its own light absorption spectrum, irradiates the gas containing the specific substance with laser light, and determines the specific substance from the amount of absorption at the specific wavelength. The concentration is measured.

  The following Patent Document 1 discloses a technique for sucking a gas from a piping unit through which a gas containing ammonia flows and guiding the sucked gas to a laser gas spectrometer to measure the concentration of ammonia contained in the gas. .

Patent Document 2 discloses a sampling pipe inserted into a flue to collect exhaust gas, a flow cell unit connected to the sampling pipe via a heating conduit, and a laser gas analyzer connected to the flow cell unit. An ammonia concentration measuring device is disclosed. In the ammonia concentration measuring device disclosed in Patent Document 2, an adsorbent that adsorbs sulfur trioxide (SO ₃ ) but passes ammonia inside the sampling pipe is loaded, and the gas from which sulfur trioxide has been removed from the exhaust gas is loaded. By introducing it into a laser gas analyzer, the measurement accuracy of ammonia is improved.

JP 2012-8008 A JP 2010-236877 A

The sampling type concentration measuring devices disclosed in Patent Documents 1 and 2 have the following problems.
It is difficult to speed up the measurement when the gas is sucked and led to the measurement pipe.
Since the concentration measurement is performed after the gas is drawn into the measurement pipe, the state of the gas flowing through the pipe and the state of the gas drawn into the measurement pipe (for example, temperature, etc.) differ, and the measurement accuracy decreases. .
Since the concentration is measured by collecting the circulating gas locally, the concentration distribution cannot be acquired even if the local gas concentration can be measured. Further, if concentration measurement is performed by sequentially changing sampling locations, it is possible to acquire a concentration distribution, but it is necessary to suck and discharge gas at each position, which is complicated and takes time.

  In addition, if there is a lot of soot such as boiler exhaust gas, there is an effect of soot in the sucked exhaust gas. It has been demanded.

  Furthermore, when measuring the concentration of ammonia in the exhaust gas, the ammonia does not gasify due to the influence of the dust contained in the exhaust gas, and adheres to the dust. Therefore, there is a problem in that ammonia that does not contribute to this denitration is intended, and this does not serve as an index for determining whether or not appropriate denitration has been performed.

  Therefore, for example, the appearance of an exhaust gas denitration system that can stably measure the nitrogen oxide concentration in the exhaust gas of a boiler device in a flue is desired.

  In view of the above problems, an object of the present invention is to provide an exhaust gas denitration system that can stably measure the concentration of nitrogen oxides in exhaust gas in a flue.

A first invention of the present invention for solving the above-mentioned problem is a plurality of reducing agent supply means arranged in a lattice shape inside a flue for flowing combustion exhaust gas and supplying a reducing agent into the combustion exhaust gas, A denitration device comprising a denitration catalyst for denitrating NOx in the combustion exhaust gas containing a reducing agent; and the denitration device provided on the outlet side of the denitration device and in the partitioned surface region perpendicular to the gas flow of the denitration device Based on the NOx concentration distribution measuring device having a plurality of probe means for measuring the NOx concentration distribution in the combustion exhaust gas by laser light, and the NOx concentration distribution obtained from the measurement result of the NOx concentration distribution measuring device, the NOx concentration is a predetermined value. Adjusting means for adjusting a reducing agent supply amount from the reducing agent supply means corresponding to the section where the denitration is insufficient, and the plurality of probe means transmit the laser beam to the surface area. And sending towards a portion of the longitudinal direction is separated a predetermined interval, comprising a light tube feeding having a measuring area where the combustion exhaust gas going out through the measurement area, among the plurality of probe means adjacent The exhaust gas denitration system is provided at different positions in the longitudinal direction of the light transmission tube.

  A second invention is the exhaust gas denitration system according to the first invention, wherein the NOx concentration distribution measuring device is provided on the inlet side of the denitration device to obtain a denitration rate.

The third invention is the invention of the first or second denitration catalyst of the denitration apparatus is composed of a plurality of layers, the NOx concentration distribution measuring apparatus, are only set during the denitration catalyst layers, each denitration catalyst the NOx concentration distribution is measured for each layer, said adjustment means, said from the measurement result of the NOx concentration distribution measuring apparatus, on the basis of the NOx concentration distribution obtained for each denitration catalyst layer, the denitration NOx concentration is a predetermined value or more unsaturated It is sufficient exhaust gas denitration system comprising a Turkey to adjust the reducing agent supply amount from the reducing agent supply means that corresponds to the partition.

According to a fourth aspect of the present invention, there are provided a plurality of reducing agent supply means for supplying a reducing agent into the combustion exhaust gas, the plurality of reducing agent supply means arranged in a lattice in the flue through which the combustion exhaust gas flows, and the combustion exhaust gas containing the reducing agent. The NOx concentration distribution in the combustion exhaust gas in the area of the denitration apparatus provided with the denitration catalyst which denitrates NOx and the outlet side of the denitration apparatus perpendicular to the gas flow of the denitration apparatus is obtained by laser light. The NOx concentration distribution measuring device having a plurality of probe means for measuring, and the NOx concentration distribution obtained from the measurement result of the NOx concentration distribution measuring device, corresponding to the section where the NOx concentration is not less than a predetermined value and the denitration is insufficient. comprising an adjustment means for adjusting the reducing agent supply amount from the reducing agent supply means, said plurality of probe means, said laser beam and sending toward the surface region, before Symbol combustion exhaust gas passing Comprising a light tube feeding having a measurement region, a rotation means for rotating the pre-Symbol light transmitting tube in the circumferential direction, are provided along the longitudinal direction of the light transmission tube, a fixed outer frame which covers the light transmission tube, A plurality of first elongated holes provided at a predetermined distance along the longitudinal direction of the light transmission tube and provided at different positions in the circumferential direction of the light transmission tube, and the transmission in the longitudinal direction of the fixed outer frame. and a second long hole provided in a plurality at a predetermined distance to a position corresponding to the first long hole of the light tube, a, when the light transmission tube is rotated, the first of the light transmission tube An exhaust gas denitration system characterized in that positions in the circumferential direction of a long hole and the second long hole of the fixed outer frame coincide with each other to form the measurement region in which the combustion exhaust gas passes through the light transmission tube. It is in.

According to a fifth invention, in any one of the first to fourth inventions, a laser transmitter that emits laser light from the outside of a measurement field to each of one end sides of the plurality of probe means, and the plurality of probes An exhaust gas denitration system comprising: a laser receiver that receives laser light that has passed through a measurement region outside the measurement field and detects the light intensity of the laser light on each of the other end sides of the means It is in.

According to a sixth invention, in any one of the first to fourth inventions, the NOx concentration distribution measuring device includes a laser transmitter that emits laser light into the probe means, and a measurement region of the probe means. A laser receiver that receives the laser light that has passed through and detects the light intensity of the laser light, a first reflector that reflects the laser light from the laser transmitter, and a probe unit A second reflecting portion that reflects the laser light that has passed through the measurement region; a light transmission window portion that is provided on each of one end sides of the plurality of probe means and through which the laser light passes from the outside of the measurement field; A light receiving window portion that is provided on each of the other end sides of the probe means and through which the laser beam that has passed through the measurement region passes outside the measurement field, and the first reflection unit are mounted on the outside of the measurement field. A first shift that moves the first reflecting portion. And parts, are the second reflective portion is placed, a second moving unit for moving the second reflecting portion outside the measuring field, based on the laser path in the interior of the probe means, said light-sending a pair of window portions are selected from use window portion and the light receiving window, is irradiated the laser beam toward the light-receiving window portion from the Okuhikariyo window one pair selected by said laser beam And a control unit that moves the first and second reflecting units by the first and second moving units so as to pass through the probe means.

According to a seventh invention, in any one of the first to fourth inventions, the NOx concentration distribution measuring device includes a laser transmitter that emits laser light into the probe means, and a measurement region of the probe means. Is provided on each of one end side of the plurality of probe means and one laser receiver that receives the laser light that has passed through and detects the light intensity of the laser light, and the laser light passes from the outside of the measurement field A light transmitting window, a light receiving window provided on each of the other ends of the plurality of probe means , through which a laser beam that has passed through a measurement region outside the measurement field, and the laser transmitter are mounted. And a second moving unit that moves the laser transmitter outside the measurement field, and a second moving unit that moves the laser receiver outside the measurement field. , Inside the probe means Based on over The path, said feeding pair of window portions from the optical window portion and the light receiving window portion is selected, the toward the light receiving window portion from the Okuhikariyo window one selected pair A control unit that moves the laser transmitter and the laser receiver by the first and second moving units so that the laser beam is irradiated and the laser beam passes through the probe means. It is in the exhaust gas denitration system.

  According to the present invention, the NOx concentration distribution measuring device detects the NOx concentration distribution of the denitration catalyst in the flue, and outputs the detection result to the opening setting unit. In the opening degree setting unit, the opening degree of the reducing agent can be controlled based on the average value of the nitrogen oxide concentration.

FIG. 1 is a schematic diagram of a boiler apparatus including a denitration apparatus according to the first embodiment. FIG. 2 is a schematic diagram of another denitration apparatus according to the first embodiment. FIG. 3 is a system diagram illustrating a schematic configuration example of the ammonia injection device of the denitration apparatus according to the first embodiment. FIG. 4 is an explanatory diagram showing a concentration distribution measurement region inside the denitration apparatus. FIG. 5 is an explanatory view showing a divided region of the concentration measurement region inside the denitration apparatus. FIG. 6 is a schematic diagram illustrating the overall configuration of the NOx concentration distribution measuring apparatus installed in the denitration apparatus according to the first embodiment. FIG. 7 is a longitudinal sectional view showing a laser beam window on the light transmission side of the NOx concentration distribution measuring apparatus installed in the denitration apparatus according to the first embodiment. FIG. 8 is a longitudinal sectional view showing a laser beam window on the light receiving side of the NOx concentration distribution measuring apparatus installed in the denitration apparatus according to the first embodiment. FIG. 9 is a schematic diagram of a NOx concentration distribution measuring apparatus installed in the denitration apparatus according to the first embodiment. FIG. 10 is a schematic diagram illustrating an overall configuration of a NOx concentration distribution measuring apparatus installed in the denitration apparatus according to the second embodiment. FIG. 11 is a schematic diagram illustrating an overall configuration of a NOx concentration distribution measuring apparatus installed in another denitration apparatus according to the second embodiment. FIG. 12 is a schematic diagram illustrating an overall configuration of a NOx concentration distribution measuring apparatus installed in the denitration apparatus according to the third embodiment. FIG. 13 is a schematic diagram illustrating an exploded configuration of the probe means of the NOx concentration distribution measuring apparatus installed in the denitration apparatus according to the third embodiment. FIG. 14 is a schematic diagram illustrating an exploded configuration of the probe means of the NOx concentration distribution measuring apparatus installed in the denitration apparatus according to the third embodiment. FIG. 15 is a conceptual diagram of absorption spectroscopy measurement. FIG. 16 is an absorption chart for absorption spectroscopy measurement. FIG. 17 is a diagram showing the relationship between the dust concentration in the exhaust gas and the laser light transmittance.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by this Example, Moreover, when there exists multiple Example, what comprises combining each Example is also included.

FIG. 1 is a schematic diagram of a boiler apparatus including a denitration apparatus according to the first embodiment. FIG. 3 is a system diagram illustrating a schematic configuration example of the ammonia injection device of the denitration apparatus according to the first embodiment. FIG. 4 is an explanatory diagram showing a concentration distribution measurement region inside the denitration apparatus. FIG. 5 is an explanatory diagram showing a divided region of the concentration measurement region inside the denitration apparatus.
As shown in FIG. 1, a boiler apparatus 100 equipped with an exhaust gas denitration system according to Embodiment 1 supplies a reducing agent (for example, ammonia: NH ₃ ) into combustion exhaust gas (hereinafter referred to as “exhaust gas”) 102 from a boiler 101. An ammonia injection device 104 as a reducing agent supply means, a denitration device 105 having a denitration catalyst 106 for denitrating NOx in the exhaust gas 102 containing the reducing agent, and an inlet side and an outlet side of the denitration device 105 A NOx concentration distribution measuring device 110 provided with a plurality of probe means for measuring the NOx concentration distribution in the exhaust gas in each of the divided surface regions orthogonal to the gas flow of the denitration device 105 and measured by the laser measuring means. The NOx concentration distribution is obtained from the measurement result of the NOx concentration distribution measuring device 110, and the NOx concentration is determined from the obtained NOx concentration distribution. Seeking more denitration insufficient compartments value is for and a degree of opening setting unit 109 is a means for adjusting the reducing agent supply amount from the reducing agent supply means corresponding to the denitration insufficient compartment.
Here, when the single molecule measurement method is used, the laser measurement means measures and judges either NO (nitrogen monoxide) or NO ₂ (nitrogen dioxide) in nitrogen oxides (NOx). Yes.
Hereinafter, in this embodiment, NO (nitrogen monoxide) is measured using the NOx concentration distribution measuring device 110 to determine whether or not denitration is insufficient, but NO ₂ (nitrogen dioxide) is measured. Alternatively, both NO (nitrogen monoxide) and NO ₂ (nitrogen dioxide) may be measured and judged.
In FIG. 1, reference numeral 107 denotes an air preheater, and 108 denotes a chimney.

  The denitration device 105 is installed in the straight pipe portion of the flue 103, injects the ammonia injection device 104 for injecting ammonia, a mixer (not shown) for mixing the injected ammonia with the combustion exhaust gas, nitrogen oxide and ammonia. A denitration catalyst 106 that decomposes into water and nitrogen after the reaction, an opening setting unit 109 that controls the ammonia injection amount, and the inlet side of the denitration device in a concentration measurement region virtually provided in the gas flow path And NOx concentration distribution measuring devices 110 and 110 for measuring the NO concentration distribution before and after the outlet side.

  For example, as shown in FIG. 3, the ammonia injection device 104 includes a total flow control valve 23 in the ammonia main system 22 of a flow path pipe connected to an ammonia supply source. The ammonia main system 22 includes a plurality of (six in the illustrated example) ammonia supply systems 26 branched from the header 24 downstream of the total flow control valve 23.

  As shown in FIG. 3, the ammonia supply system 26 includes a flow control source valve 25 and a plurality of (three in the illustrated example) injection nozzles 27, each of which is a flow path for flowing exhaust gas. The injection nozzles 27 are installed inside the passage 103 so as to have a grid-like arrangement. The injection nozzle 27 causes the ammonia supplied from the ammonia supply source through the ammonia main system 22, the header 24, and the ammonia supply system 26 of the flow path piping to flow out into the flue 103 in the form of droplets or gas, and burns Ammonia as a reducing agent is injected into the exhaust gas. In addition, ammonia injected in the form of droplets absorbs heat from high-temperature combustion exhaust gas and is gasified.

  The ammonia gas thus injected into the flue 103 is mixed with the combustion exhaust gas by passing through the mixer. As a result, ammonia reacts with the nitrogen oxides and passes through the denitration catalyst 106 in the denitration device 105, so that the nitrogen oxides are removed from the combustion exhaust gas by being decomposed into water and nitrogen.

  A measured value of the nitric oxide (NO) concentration measured by the NOx concentration distribution measuring device 110 is input to the opening setting unit 109 via the control device 20. The opening setting unit 109 that has received such an input of NO concentration sets the opening of the total flow control valve 23 (opening control) based on the average value of the NO concentration, and adjusts the NO concentration at a plurality of locations. Based on this, the opening of each flow control source valve 25 is set (opening control). That is, the opening setting unit 109 outputs an opening control signal of the total flow control valve 23 and the flow control source valve 25 based on the NO concentration distribution.

  In this case, the opening degree control of the flow control source valve 25 by the opening degree setting unit 109 is performed based on a control map that defines a correlation between a predetermined ammonia concentration and an opening degree for each flow control source valve 25. In other words, the denitration device 105 is produced by obtaining the correlation data in advance through experiments or the like because various conditions (the channel system of the flue 103, the channel cross-sectional area, the type of fuel, etc.) differ for each boiler 101. The control map is stored in the opening setting unit 109. In this control map, the opening degree of the flow control source valve 25 that is different for each of the plurality of ammonia supply systems 26 with respect to the NO concentration at a plurality of positions where the NO concentration in the flue 103 is measured in the same flow path cross section. Are set individually.

As described above, the NOx concentration distribution measuring apparatus 110 creates the NO concentration distribution in the concentration measurement region virtually set in the cross section of the flue channel on the inlet side and the outlet side of the NOx removal catalyst 106, and this NO The concentration distribution is output to the opening setting unit 109.
At this time, since the NO concentration is measured at the inlet side and the outlet side of the denitration device 105, the denitration rate can be obtained simultaneously.

  According to such a denitration device 105, the NOx concentration distribution measuring device 110 detects the NO concentration distribution on the inlet side and the outlet side of the denitration catalyst 106 in the flue, and the detection result is output to the opening setting unit 109. The In the opening setting unit 109, the opening control of the total flow control valve 23 is performed based on the average value of the nitrogen oxide concentration, and the flow control is performed based on the NO concentration distribution obtained by the NOx concentration distribution measuring device 110. The opening control of the main valve 25 is performed. Thereby, the ammonia injection amount distributed to each of the plurality of ammonia supply systems 26 can be automatically adjusted according to the measured value of the NO concentration with a short time constant while continuing the operation of the denitration apparatus 105.

  At this time, since the opening degree control of the flow control source valve 25 is performed based on a map of a predetermined ammonia concentration and the opening degree of each flow control source valve 25, the total supply amount is defined by the nitrogen oxide concentration. The amount of ammonia distributed to the ammonia supply system 26 is adjusted according to the opening degree of the flow control main valve 25.

  A high detected value of NO concentration means that the catalytic performance of the NOx removal catalyst 106 has deteriorated, and therefore corresponds to the channel cross-sectional position of the flue from the NO concentration distribution measured by the NOx concentration distribution measuring device 110. The deterioration state of the denitration catalyst 106 can be grasped.

  Thus, since the NO concentration distribution is related to the performance deterioration of the denitration catalyst 105, if the ammonia injection amount distribution control by the ammonia injection device 104 is performed based on the NO concentration distribution, the downstream side of the denitration device 105 It is possible to control the distribution of leaked ammonia discharged excessively. In addition, since leaked ammonia also causes the air preheater 107 to be blocked, if the distribution control of the ammonia injection amount by the ammonia injection device 104 is performed based on the NO concentration detection, the air preheater 107 can be prevented from being blocked. Become.

  According to the denitration apparatus 105 according to the present embodiment, the reducing agent injection amount distributed for each of the plurality of reducing agent supply systems according to the measured value of the NO concentration with a short time constant while continuing the operation of the denitration apparatus 105. Can be automatically adjusted. As a result, it is possible to extend the life of the denitration catalyst 106 and optimize the renewal of the denitration catalyst 106 by optimizing the distribution of reducing agent injection. As a result, in the denitration apparatus 105, it is possible to realize cost reduction and optimization of ammonia consumption accompanying the renewal of the denitration catalyst 106.

  In this embodiment, the NOx concentration distribution measuring device 110 is installed on the inlet side and the outlet side of the denitration device 105 and the NO concentration is measured, so the denitration rate is obtained, but the present invention is limited to this. The NOx concentration distribution measuring device 110 is provided only on the outlet side of the denitration device 105, and the NO concentration in the exhaust gas when passing through the denitration device is measured to check whether it is below a predetermined value. When the value is equal to or greater than the predetermined value, an opening degree signal is sent from the opening degree setting unit 109 to the ammonia injection device 104 via the control device 20, and the ammonia injection amount distributed to each ammonia supply system 26 is automatically adjusted. You may make it do.

  Next, the concentration distribution measurement using the NOx concentration distribution measuring apparatus 110 will be described in detail.

FIG. 4 is a diagram for explaining the NO concentration distribution measurement region in the present embodiment. As shown in FIG. 4, the measurement target is included in the internal space of the flue of the denitration apparatus 105 as the measurement target device. Exhaust gas 102 is circulating. Note that the denitration catalyst 106 is omitted.
A concentration measurement region S is virtually set in the internal space of the denitration device 105. The density measurement area S is an area arbitrarily set in the internal space. In the present embodiment, as shown in FIG. 5, the denitration device 105 is divided into five rows in a direction parallel to the in-plane direction of the wall surface of the flue, and three rows from the first wall portion 103a to the second wall portion 103b. In the case of the division into 15 areas, the density measurement area S is virtually divided into 15 divided areas. The concentration distribution of the measurement target in the concentration measurement region S can be obtained by measuring the average density of the measurement target for each of the divided areas.

FIG. 6 is a schematic diagram showing the overall configuration of the NOx concentration distribution measuring apparatus installed in the denitration apparatus.
As shown in FIG. 6, the NOx concentration distribution measuring apparatus 110A is provided with probe means having a plurality of light transmission tubes 112A (112B, 112C) for measuring the divided areas.

  Further, as shown in FIG. 6, a laser transmitter 11 for emitting laser light from the outside of the measurement field to each of one end sides of the light transmitting cylinders 112A (112B, 112C) of the plurality of probe means, and the other end A laser receiver 12 that receives laser light that has passed through the measurement region outside the measurement field and detects the light intensity of the laser light is provided on each side.

  As shown in FIG. 6, in this embodiment, probe means comprising three light transmission tubes 112A, 112B, and 112C having three different measurement areas L are prepared so as to correspond to the 15 sections shown in FIG. Yes. The probe means of the light transmission cylinders 112A to 112C are set as one set, and five sets (I to V) are arranged in the column direction.

FIG. 7 is a perspective view of the probe means constituting one basic set.
As shown in FIG. 7, the probe means for forming three different measurement areas L constituting one basic set includes a hollow light transmission tube 112A (112B, 112C) that passes laser light, and the light transmission tube. A part of 112A (112B, 112C) is divided by a predetermined distance 112a, 112b, and has a measurement region L exposed to the measurement field.
Since the exhaust gas 102 passes through the divided measurement region L, NO in the exhaust gas can be measured.
The measurement region L is interrupted for 1 m, and the laser optical path length is 1 m.

  Thus, in the measurement region L, which is a predetermined divided region for measuring the NO concentration, a part of the light transmission tube 112 is divided between the predetermined distances 112a and 112b. Therefore, on the laser path, the exhaust gas 102 exists only in the measurement region L where the light transmission tube 11 is cut off, and the concentration of NO in the exhaust gas 102 in the measurement region L can be measured by absorption of the laser beam.

In this embodiment, as shown in FIG. 6, the light transmission tube 112 </ b> A is divided into the first column I, the second column II, the third column III, the fourth column IV, and the fifth column V on the light receiver 12 side. _{(P 1, P 4, P} 7, P 10, P 13) so as to correspond to a predetermined distance 112a, is exposed measurement area L to 112b between separated measurement field is provided.
Further, the light transmission tube 112B includes divided regions (P ₂ , P ₅ , P ₈ , P ₁₁ , P _{14) of} the first column I, the second column II, the third column III, the fourth column IV, and the fifth column V. ), A measurement region L that is exposed to a measurement field separated by a predetermined distance 112a, 112b is provided.
In addition, the light transmission tube 112C includes divided regions (P ₃ , P ₆ , P ₉ , P ₁₂ , P _{15) of} the first column I, the second column II, the third column III, the fourth column IV, and the fifth column V. ), A measurement region L that is exposed to a measurement field separated by a predetermined distance 112a, 112b is provided.
In FIG. 6, the measurement region L is not shown.

  Therefore, in order to measure the density of only one divided region, the hollow light transmitting tubes 112A to 112C are installed in the laser path of the divided region where the concentration is not measured.

  8 and 9 are views schematically showing the laser beam window 15 and the light transmission tube 112A (112B, 112C). As shown in FIGS. 8 and 9, the laser beam window 15 is a hollow member, and is fixed to the surfaces of the outer walls 103 a and 103 b of the denitration apparatus 105 by flanges 16. Inside the laser beam window 15, a sealing optical glass 17 is provided to block gas in and out between the inside and the outside. The light receiving surface of the sealing optical glass 17 may be formed obliquely rather than perpendicular to the laser light in order to prevent reflection of the laser light.

  An air supply port 18 is provided on each side of the sealing optical glass 17 of the laser beam window 15. By blowing out the seal air 19 from the air supply port 18, it is possible to prevent adhesion of a substance to the sealing optical glass 17. Note that the seal air 19 may be blown out only to the density measurement region S side, not the double-sided side with respect to the sealing optical glass 17.

  Further, the seal air 19 supplied into the light-transmitting tubes 112A to 112C is filled, thereby preventing the inflow (backflow) of the exhaust gas 102 from the opened measurement region L.

  When the light transmission tube 112A (112B, 112C) is installed on the inner wall surface, as shown in FIGS. 8 and 9, for example, the end of the light transmission tube 112A (112B, 112C) is connected to the end of the flange 16. The The diameter of the light transmission tube 112A (112B, 112C) is larger than the diameter of the laser beam window 15, and the seal air 19 supplied to the laser beam window 15 is supplied to the inside of the light transmission tube.

  Note that the method of forming the divided regions in the density measurement region S is not limited to the above-described 15 pieces of 5 columns × 3 rows. The number of columns, the number of rows, and the number of divided regions may be other numbers. When the density measurement region S is M columns × N rows and P divided regions are formed, laser paths of P probe means are set.

Next, the principle of concentration distribution measurement according to this embodiment will be described with reference to the drawings. Here, FIG. 15 is a conceptual diagram of absorption spectroscopy measurement. FIG. 16 is an absorption chart for absorption spectroscopy measurement.
The Lambert-Beer law is known as a relational expression indicating the relationship between the light intensity of the laser beam and the concentration of the measurement object.

As shown in FIG. 15, Lambert-Beer's law is that the measurement region, which is the distance of the laser path between the light transmission point and the light reception point, is L, the irradiation intensity of the laser light is I ₀ , and the light reception of the laser light. When the intensity is I (L) and the concentration of the measurement target (NO) existing in the distance L is C ₀ , the relationship of the following expression (1) is established.
I (L) = I ₀ exp (−kC ₀ L) (1)
Here, k is a proportionality coefficient set according to the absorbance of the measurement target.

Assuming that the density average value of the divided area for measuring the density of the measurement object is C ₁ and the distance of the laser path in the divided area (measurement area L where the light transmission tube is divided) is L ₁ , the above equation (1) Can be expressed as the following equation (2).
I (L) = I ₀ exp (−kC ₁ L ₁ ) (2)

When irradiating laser light for each preset laser path, the distance of the laser path in the divided area (measurement area that is a place where the light transmission cylinder is divided) L ₁ , the irradiation intensity I ₀ of the laser light, and the laser light received light intensity I (L), since it is known, by the above equation (2) can be calculated the density average value C ₁ of the divided regions is unknown.

  In the NOx concentration distribution measuring apparatus 110 having the above-described configuration, the NO concentration distribution in the concentration measuring region S is acquired by the following procedure.

Further, since the exhaust gas 102 from the boiler 101 contains soot and dust, if the optical path length of the laser light that is the measurement region L is increased, the light transmittance is attenuated by the effect of soot and dust.
FIG. 17 is a diagram showing the relationship between the dust concentration in the exhaust gas and the laser light transmittance.
In FIG. 17, when the wavelength is 1.5 μm, it is confirmed that measurement is possible with an optical path length of 2 m in coal ash having a dust concentration of about 6 g / Nm ³ .
Therefore, when the dust concentration is higher than that, it is preferable to measure with an optical path length of 1.5 m, more preferably around 1 m.

  Here, in order to measure NOx in the exhaust gas, a quantum cascade laser (semiconductor element: InGaAs / InAlAs can be exemplified. Wavelength: 5 to 6 μm, output: 1 mW) is used.

  In the present embodiment, as shown in FIG. 6, a control device 20 for controlling the quantum cascade laser is installed. The control device is, for example, a computer, a CPU, a ROM (Read Only Memory) for storing a program executed by the CPU, a RAM (Random Access Memory) functioning as a work area when executing each program, a large capacity It includes a hard disk drive (HDD) as a storage device, a communication interface for connecting to a communication network, and an access unit to which an external storage device is mounted. These units are connected via a bus. Furthermore, the control device 20 may be connected to an input unit such as a keyboard and a mouse and a display unit including a liquid crystal display device that displays data.

  The storage medium for storing the program executed by the CPU is not limited to the ROM. For example, other auxiliary storage devices such as a magnetic disk, a magneto-optical disk, and a semiconductor memory may be used. In the present embodiment, the control device is realized by a single computer, but may be realized by a plurality of computers.

  First, the quantum cascade laser transmitter 11 is activated by the control device 20 so as to correspond to the laser path to be measured, and after the output of the laser light is stabilized, measurement in the laser path is performed.

  After the measurement in this laser path is completed, the measurement in the next laser path is started. In this way, measurement for each laser path is sequentially performed. Thereafter, laser light is emitted from the light transmitter 11, and the laser light absorbed by the measurement object as the laser light passes through a predetermined laser path is received by the light receiver 12.

The light receiver 12 detects the light intensity from the received light. The detected value of the laser beam is output to the control device 20. At this time, the control device 20 can associate the detection value by the light receiver 12 with the identification information (P _{1 to} P ₁₅ ) of the laser path corresponding to the detection value.

  The detection value and the laser path information input to the control device 20 are stored in the control device 20 in association with each other. Furthermore, the control device 20 also stores the irradiation intensity of the laser light from the light transmitter 11 during the laser irradiation. Then, the control device 20 creates a NO concentration distribution based on the stored data.

Specifically, the distance between the divided areas on each laser path, the input detection value, and the irradiation intensity of the laser light are read out, and the divided areas are obtained by using the density calculation formula represented by the above expression (2). The concentration of each measurement target is calculated. Then, the density distribution of the density measurement area S is created by interpolating the density of each divided area. Thereby, the density distribution of the measurement object in the density measurement region S is obtained.
The density distribution of the density measurement region S obtained in this manner is presented to the user by being displayed on a display device (not shown) connected to the control device 20, for example.

  If all of the NO concentration distribution is below a predetermined value, the operation is continued under the same conditions. In this case, the injection amount of the ammonia injection device 104 is not adjusted.

  On the other hand, if the control device 20 determines that there is a place where the concentration is high in a part of the NO concentration distribution, the information signal of the opening setting unit 109 is sent. Then, in the opening degree setting unit 109, the opening degree control of the flow control source valve 25 is performed so that ammonia from the ammonia injection device 104 corresponding to the specified place where the NO concentration distribution is high can be injected. Thereby, the ammonia injection amount distributed to each of the plurality of ammonia supply systems 26 can be automatically adjusted according to the measured value of the NO concentration while continuing the operation of the denitration apparatus 105.

  As a result, by measuring the NO concentration distribution by the NOx concentration distribution measuring device 110 at the inlet side and the outlet side of the denitration device, it can be confirmed whether the denitration is uniformly performed in real time.

Here, in the operation of the denitration apparatus, the leak ammonia concentration at the outlet side of the denitration apparatus may be measured to determine whether the denitration is properly performed. In such a case, there are the following problems. That is, even if ammonia is injected into the exhaust gas 102 from the ammonia injection device 104, if there is a large amount of soot in the exhaust gas, ammonia may not be gasified and will adhere to the soot and may not contribute to denitration.
Therefore, for example, when measuring leak ammonia on the outlet side of the denitration apparatus, ammonia that does not contribute to this denitration is measured, and it does not serve as an index for determining whether or not appropriate denitration has been performed.
On the other hand, as in the present invention, the NO concentration is directly measured by the NOx concentration distribution measuring device 110 on the inlet side and the outlet side of the denitration device 105, thereby confirming that denitration is reliably performed. be able to.

FIG. 2 is a schematic diagram of another denitration system of the first embodiment. In the denitration apparatus 105 shown in FIG. 1, the NOx concentration distribution measuring devices 110 are installed on the inlet side and the outlet side, respectively. The invention is not limited to this, and when the NOx removal catalyst of the NOx removal device 105 is installed in a plurality of stages (two or more stages), the NOx concentration distribution measuring device 110 is installed between the layers. May be.

FIG. 2 illustrates a case where the denitration catalyst is composed of two upstream denitration catalyst layers 106A and downstream denitration catalyst layers 106B, but the present invention is not limited to two layers.
In this embodiment, a NOx concentration distribution measuring device (inlet) 110 is installed on the inlet side of the upstream denitration catalyst layer 106A, and a NOx concentration distribution measuring device is provided between the upstream denitration catalyst layer 106A and the downstream denitration catalyst layer 106B. (Intermediate) 110 is installed, a NOx concentration distribution measuring device (exit) 110 is installed on the outlet side of the downstream denitration catalyst layer 106B, and the NO concentration distribution in the space between each layer is measured. The ammonia injection is adjusted based on the measurement result of the concentration distribution.

  As a result, when the denitration catalyst is disposed in a plurality of layers, it can be determined which denitration rate of which section of which denitration catalyst layer is reduced.

FIG. 10 is a schematic diagram illustrating an overall configuration of a NOx concentration distribution measuring apparatus installed in the denitration apparatus according to the second embodiment.
The same members as those in the configuration of the NOx concentration distribution measuring apparatus according to the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
In the NOx concentration distribution measuring apparatus 100A installed in the denitration apparatus according to the first embodiment shown in FIG. 6, the light transmitter 11 and the light receiver 12 are installed in each of the probe means. The probe means is provided with a window portion 15A (15B), a reflection mirror 13A (13B) corresponding to the window portion is provided, and a single light transmitter 11 and light receiver 12 transmit and receive laser light. Light is received.

  As shown in FIG. 10, the NOx concentration distribution measuring apparatus 100B of this embodiment includes a laser transmitter 11 that emits laser light into the probe means and a laser that has passed through the measurement region L of the probe means. One laser receiver 12 that receives light and detects the light intensity of the laser light, a first reflecting mirror 13A that reflects the laser light from the laser transmitter 11, and measurement in the probe means A second reflecting mirror 13B that reflects the laser light that has passed through the region L; a light transmission window portion 15A that is provided on each of one end sides of the plurality of probe means and through which the laser light passes from the outside of the measurement field; A light receiving window 15B that is provided on each of the other end sides of the plurality of probe means and through which the laser light that has passed through the measurement region L passes outside the measurement field, and the first reflection mirror 13A are placed and measured. Outside the field The first moving part 14a for moving the first reflecting mirror 13A and the second reflecting mirror 13B are mounted, and the second moving mirror 14B moves outside the measuring field. Two windows are selected from the first and second windows 15A and 15B based on the moving part 14b and the laser path inside the probe means, and the selected first window The first and second moving parts 14a and 14b allow the first and second moving parts 14a and 14b to irradiate the laser light from the part 15A toward the other second window part 15B and pass the probe light. And a control unit 20 that moves the second reflecting mirrors 13A and 13B.

  The light transmitter 11 and the light receiver 12 according to the present embodiment are respectively fixed at one place, and the irradiation direction of the laser light of the light transmitter 11 and the light reception direction of the laser light of the light receiver 12 are constant. In the example shown in FIG. 10, the light transmitter 11 is installed at the outer corner of the flue of the denitration apparatus, and irradiates the laser beam toward the first reflecting mirror 13 </ b> A in parallel with the long-side wall surface 103 a. To do. The light receiver 12 is installed at a position symmetrical to the light transmitter 11 and receives the laser beam reflected by the second reflecting mirror 13B parallel to the long side wall surface 103b. The guide rail 14 is installed parallel to the wall surface outside the flue, and the first and second reflection mirrors 13A and 13B placed on the movable bases 14a and 14b, which are moving parts, are provided. Move to the outside of the flue parallel to the wall.

  Since the configuration of the probe means having the light transmission tubes 112A to 112C is the same as that of the first embodiment, the description thereof is omitted.

  The light transmitter 11 is controlled by a control device 20 connected by a control cable 21. As the laser light emitted by the light transmitter 11, light that outputs an appropriate wavelength according to the absorbance characteristic of the measurement target is employed. The start / stop signal of the light transmitter 11 is controlled by outputting the start / stop signal by the control device 20.

  The guide rail 14 and the reflection mirror 13 are controlled by a control device 20 connected by a control cable 21. When the movable table 14a provided on the guide rail 14 is moved by the control device 20 and the angle of the reflection mirror 13 is adjusted, the laser light emitted from the light transmitter 11 is reflected on the reflection mirror 13 on the light transmitter 11 side. And is irradiated toward the density measurement region S. Further, the laser light that has passed through the density measurement region S is reflected by the reflection mirror 13 on the light receiver 12 side and is received by the light receiver 12.

  The control device 20 is notified of the irradiation intensity of the laser light emitted from the light transmitter 11 and the received light intensity detected by the light receiver 12. The light receiver 12 converts the input light information into an electrical signal and outputs the electrical signal to the control device 20.

  Note that the guide rail 14 may not necessarily be arranged on a straight line due to the influence of the installation location. However, if the angle of the reflection mirror 13 can be finely adjusted for each laser path, the influence of the installation location of the guide rail 14 may be reduced. The laser beam can reach the light receiver 12 from the light transmitter 11 without receiving the light. This can be realized by the control device 20 storing the angle of the reflection mirror 13 for each laser path.

In the concentration distribution measuring apparatus 110 having the above configuration, the concentration distribution in the concentration measuring region S is acquired by the following procedure.
First, the movable table 14a on which the reflection mirror 13 is placed is moved on the guide rail 14 so as to correspond to the laser path to be measured, and the angle of the reflection mirror 13 is adjusted. Then, after the light transmitter 11 is activated by the control device 20 and the output of the laser light is stabilized, measurement in the laser path is performed.

After the measurement in this laser path is completed, the measurement in the next laser path is started. In this way, measurement for each laser path is sequentially performed. For example, the movable base 14a is sequentially moved according to a predetermined order set in advance, and the angle of the reflection mirror 13 is adjusted according to the laser path. Thereafter, laser light is emitted from the light transmitter 11, and the laser light absorbed by the measurement object as the laser light passes through a predetermined laser path is received by the light receiver 12.
The arrangement positions of the plurality of laser beam windows 15A and 15B around the outer wall of the flue and the light transmission tube 112 in the probe means are the same as in the above-described embodiment. The concentration distribution measurement method is also the same as that in the above-described embodiment, and detailed description thereof is omitted.

  According to the present embodiment, there is no need to install the light transmitter 11 and the light receiver 12 for each probe means as in the first embodiment, so that one laser device can be provided.

Next, a modified example of the NOx concentration distribution measuring apparatus according to the present embodiment will be described.
FIG. 11 is a schematic diagram illustrating an overall configuration of a NOx concentration distribution measuring apparatus installed in another denitration apparatus according to the second embodiment.
In the concentration distribution measuring apparatus 100B described with reference to FIG. 10, the light transmitter 11 and the light receiver 12 are fixed, and the first and second reflecting mirrors 13A and 13B include the first and second movable bases 14a. 14b, and the first and second reflection mirrors 13A and 13B move on the guide rail 14, but the present invention is not limited to this example. For example, as in the concentration distribution measuring apparatus 100C shown in FIG. 11, the light transmitter 11 and the light receiver 12 are placed on the first and second movable bases 14a and 14b, and the light transmitter 11 and the light receiver 12 are guided. It may be moved on the rail 14.

  That is, the NOx concentration distribution measuring apparatus 100 according to the modified example includes a light transmitter 11 that has a laser light source and emits laser light, a light receiver 12 that has a light detection unit and receives laser light, and first and first elements. Two movable bases 14a, 14b are movably mounted on guide rails 14 and laser beam windows 15A, 15B installed on the wall of the flue. The guide rail 14 is installed in parallel to the wall surface of the flue outside the flue.

  The light transmitter 11 and the light receiver 12 are mounted on different first and second movable bases 14a and 14b, respectively, and move parallel to the roadside wall outside the flue. Therefore, the light transmitter 11 can irradiate the laser beam window 15A provided on the outer wall surface of the flue according to the laser path, and the light receiver 12 can irradiate the laser beam window 15B according to the laser path. The laser beam that has passed can be received.

  The arrangement positions of the plurality of laser beam windows 15A and 15B around the outer wall of the flue and the light transmission tube 112 in the probe means are the same as in the above-described embodiment. The concentration distribution measurement method is also the same as that in the above-described embodiment, and detailed description thereof is omitted.

  According to the present embodiment, there is no need to install the first and second reflecting mirrors 13A and 13B unlike the NOx concentration distribution measuring apparatus 100B shown in FIG. 10, and therefore the laser apparatus configuration can be further simplified. Can do.

FIG. 12 is a schematic diagram illustrating an overall configuration of a NOx concentration distribution measuring apparatus installed in the denitration apparatus according to the third embodiment. FIG. 13 is a schematic diagram illustrating an exploded configuration of the probe means of the NOx concentration distribution measuring apparatus installed in the denitration apparatus according to the third embodiment. FIG. 14 is a schematic diagram illustrating an exploded configuration of the probe means of the NOx concentration distribution measuring apparatus installed in the denitration apparatus according to the third embodiment. The same members as those in the configuration of the NOx concentration distribution measuring apparatus according to the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
As shown in FIG. 12, the probe means of the NOx concentration distribution measuring apparatus according to the present embodiment includes a light transmission cylinder 121 that passes laser light, a rotation means 122 that rotates the light transmission cylinder 121, and a light transmission that rotates. A fixed outer frame 123 that covers the whole of the cylinder 121 along the longitudinal direction, and is formed on the light-transmitting cylinder 121. (In the embodiment, three places) The first long holes 124a, 124b, 124c that are opened and the second long hole 125a that is formed in the fixed outer frame 123, and a plurality of portions in the longitudinal direction are opened at a predetermined distance. , 125b, 125c and when the light transmission tube rotates, the first long hole 124a of the light transmission tube coincides with the second long hole 125a of the fixed outer frame, and the measurement region L exposed to the measurement field. Form.
In addition, since the light receiver 12 is disposed inside the rotating unit 122, the illustration is omitted.

  FIG. 13 is an exploded perspective view of the light transmission cylinder 121 rotated clockwise by the rotating means and the fixed outer frame 123 covering the whole along the longitudinal direction of the rotating light transmission cylinder 121. Note that the oblong holes in the opening are hatched for emphasis.

First, a first long hole 124a, 124b having a predetermined distance in a part of its longitudinal direction and a plurality of (three in the present embodiment) openings at different locations in the longitudinal direction in the longitudinal direction is provided in the light transmission tube 121. 124c is formed.
The first elongated holes 124a, 124b, and 124c are also formed with the same holes at the same opposite positions in the circumferential direction (locations that are 180 degrees out of phase) to enable gas flow.

In addition, the fixed outer frame 123 into which the light transmission tube is inserted has second long holes 125a, 125b, and 125c in which a plurality of (three in the present embodiment) openings in the longitudinal direction are opened at a predetermined distance. Is formed.
As shown in FIG. 14, the second long holes 125a, 125b, and 125c are also formed at the same location facing each other in the circumferential direction, and allow gas to flow in the vertical direction in the figure.

  Then, as shown in FIG. 14, when the light transmission cylinder 121 is inserted into the fixed outer frame 123 and rotated by the rotating means 122, the long holes 123a, 123b, 123c formed in a clockwise direction are rotated. Accordingly, the measurement region L exposed to the exhaust gas in the measurement field is formed when the second long holes 125a, 125b, and 125c of the fixed outer frame sequentially coincide with each other.

  Further, a laser transmitter that irradiates laser light is installed in the rotating means 122, and the laser light is irradiated into the light transmitting cylinder.

  As a result, a plurality of measurement regions L can be made to appear along the longitudinal direction of the probe means by performing a predetermined rotation using the rotating light transmission cylinder 121, for example, as in the first embodiment. With the three probe means, it is not necessary to use a single-row I measuring means, and the apparatus can be simplified.

DESCRIPTION OF SYMBOLS 11 Light transmitter 12 Light receiver 13 Reflection mirror 14 Moving part 15 Window part 19 Seal air 20 Control apparatus 21 Control cable S Concentration measurement area 100 Boiler apparatus 101 Boiler 102 Combustion exhaust gas (exhaust gas)
DESCRIPTION OF SYMBOLS 103 Flue 104 Ammonia injection apparatus 105 Denitration apparatus 106 Denitration catalyst 110,110A-110C NOx concentration distribution measuring apparatus

Claims (7)

A plurality of reducing agent supply means arranged in a lattice pattern inside a flue for flowing combustion exhaust gas, and supplying a reducing agent into the combustion exhaust gas;
A denitration apparatus comprising a denitration catalyst for denitrating NOx in the combustion exhaust gas containing a reducing agent;
A NOx concentration distribution measuring device provided with an outlet side of the denitration device and having a plurality of probe means for measuring the NOx concentration distribution in the combustion exhaust gas in a sectioned surface region orthogonal to the gas flow of the denitration device with a laser beam When,
Based on the NOx concentration distribution obtained from the measurement result of the NOx concentration distribution measuring device, the adjusting means for adjusting the reducing agent supply amount from the reducing agent supply means corresponding to the section where the NOx concentration is not less than a predetermined value and the denitration is insufficient. And
Wherein the plurality of probe means, said laser beam and sending toward the surface region, a part of the length is separated a predetermined interval, comprising a light tube feeding having a measuring area where the combustion exhaust gas going out through The exhaust gas denitration system is characterized in that the measurement region is provided at different positions in the longitudinal direction of the light transmission cylinder between the plurality of adjacent probe means. In claim 1,
An exhaust gas denitration system characterized in that the NOx concentration distribution measuring device is provided on the inlet side of the denitration device to obtain a denitration rate. In claim 1 or 2,
The denitration catalyst of the denitration device is composed of a plurality of layers,
The NOx concentration distribution measuring device is provided between each denitration catalyst layer, measures the NOx concentration distribution for each denitration catalyst layer,
The adjusting means is based on the NOx concentration distribution obtained for each denitration catalyst layer from the measurement result of the NOx concentration distribution measuring device, and the reducing agent supply means corresponding to the section where the NOx concentration is not less than a predetermined value and the denitration is insufficient. An exhaust gas denitration system characterized by adjusting the amount of reducing agent supplied from the exhaust gas. A plurality of reducing agent supply means arranged in a lattice pattern inside a flue for flowing combustion exhaust gas, and supplying a reducing agent into the combustion exhaust gas;
A denitration apparatus comprising a denitration catalyst for denitrating NOx in the combustion exhaust gas containing a reducing agent;
A NOx concentration distribution measuring device provided with an outlet side of the denitration device and having a plurality of probe means for measuring the NOx concentration distribution in the combustion exhaust gas in a sectioned surface region orthogonal to the gas flow of the denitration device with a laser beam When,
Based on the NOx concentration distribution obtained from the measurement result of the NOx concentration distribution measuring device, the adjusting means for adjusting the reducing agent supply amount from the reducing agent supply means corresponding to the section where the NOx concentration is not less than a predetermined value and the denitration is insufficient. And
Wherein the plurality of probe means, said laser beam and sending toward the surface region, before SL includes a light transmitting tube has a measurement area where the combustion exhaust gas going out through,
Rotating means for rotating the pre-Symbol light transmitting tube in the circumferential direction,
A fixed outer frame provided along the longitudinal direction of the light transmission tube and covering the light transmission tube;
A plurality of first elongated holes provided at a predetermined distance along the longitudinal direction of the light transmission tube, and provided at different positions in the circumferential direction of the light transmission tube;
A plurality of second long holes provided at a predetermined distance in positions corresponding to the first long holes of the light transmission tube in the longitudinal direction of the fixed outer frame ,
When the light transmission tube rotates, the circumferential positions of the first long hole of the light transmission tube and the second long hole of the fixed outer frame coincide with each other, and the combustion exhaust gas is transmitted to the light transmission tube. An exhaust gas denitration system characterized by forming the measurement region passing through a cylinder. In any one of Claims 1 thru | or 4,
A laser transmitter that emits laser light from the outside of the measurement field to each of one end sides of the plurality of probe means;
Each of the other end sides of the plurality of probe means includes a laser receiver that receives a laser beam that has passed through a measurement region outside a measurement field and detects a light intensity of the laser beam. Exhaust gas denitration system. In any one of Claims 1 thru | or 4,
NOx concentration distribution measuring device
One laser transmitter for emitting laser light into the probe means;
A laser receiver that receives the laser light that has passed through the measurement region of the probe means, and detects the light intensity of the laser light;
A first reflecting portion for reflecting the laser beam from the laser transmitter;
A second reflecting portion that reflects the laser beam that has passed through the measurement region in the probe means;
Provided on each one end side of the plurality of probe means, a light transmission window portion through which laser light passes from the outside of the measurement field,
A light receiving window provided on each of the other ends of the plurality of probe means, through which a laser beam that has passed through the measurement region outside the measurement field passes;
A first moving unit on which the first reflecting unit is mounted and moves the first reflecting unit outside the measurement field;
A second moving unit on which the second reflecting unit is mounted and moves the second reflecting unit outside the measurement field;
Based on a laser path inside the probe means, a pair of window portions is selected from the light transmission window portion and the light reception window portion, and the light reception window portion is selected from the selected pair of light transmission window portions. A control unit that moves the first and second reflecting units by the first and second moving units so that the laser beam is irradiated toward the laser beam and passes through the probe means. An exhaust gas denitration system characterized by In any one of Claims 1 thru | or 4,
NOx concentration distribution measuring device
One laser transmitter for emitting laser light into the probe means;
A laser receiver that receives the laser light that has passed through the measurement region of the probe means, and detects the light intensity of the laser light;
Provided on each one end side of the plurality of probe means, a light transmission window portion through which laser light passes from the outside of the measurement field,
A light receiving window provided on each of the other ends of the plurality of probe means, through which a laser beam that has passed through the measurement region outside the measurement field passes;
A first moving unit on which the laser transmitter is mounted and moves the laser transmitter outside the measurement field;
A second moving unit on which the laser receiver is mounted and moves the laser receiver outside the measurement field;
Based on a laser path inside the probe means, a pair of window portions is selected from the light transmission window portion and the light reception window portion, and the light reception window portion is selected from the selected pair of light transmission window portions. A control unit that moves the laser transmitter and the laser receiver by the first and second moving units so that the laser beam is irradiated toward the laser beam and passes through the probe means. An exhaust gas denitration system characterized by

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