JP2002162393A - Method and device for simultaneously analyzing nox and nh3 - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for simultaneously analyzing NOX and NH3 in the exhaust gas within a flue of an electric power facility, for example. SOLUTION: A device for simultaneously measuring nitrogen oxide(NOX) and ammonia(NH3) in an exhaust gas 11 comprises first and second measurement lines 12A and 12B for measuring the exhaust gas 11 blanched in two lines, an ammonia oxidizing catalyst 13 for oxidizing ammonia, a first NOX gauge 14 which is provided in the lower stream of the ammonia oxidizing catalyst 13 and measures the concentration of NOX, a first denitration catalyst 15 which is provided on the second measurement line 12B and denitrates NOX, a second denitration catalyst 16 which denitrates NOX in the gas wherein the exhaust gasses of the first and second measurement lines 12A and 12B are merged, a second NOX gauge 17 which is provided in the lower stream of the second denitration catalyst 16 and measures the concentration of NOX, and a calculator 18 which receives the sensor output from the first NOX gauge 14 and the second NOX gauge 17 for calculating/measuring the concentration of NOX and NH3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a device capable of simultaneously analyzing for example power plants, etc. in the flue gas of NOx and NH _3.

[0002] For example, nitrogen oxides (NOx) contained in exhaust gas from boilers, gas turbines and the like used in power generation facilities and the like
Conventionally, chemiluminescence-type analyzers have been used for measurement, but there are problems such as the inability to obtain measurement results in real time and complicated measurement operations. A way was desired.

On the other hand, as a method for detecting various gas concentrations, for example, there are chemical sensors such as an oxygen sensor and a combustible gas detector. Chemical sensors include a semiconductor type, an electromotive type, and an electrolytic type, and a sensor material is selected according to a gas to be detected. However, it has a characteristic that it has a quick response speed and is easy to use. Further, as a NO concentration measurement technique other than the chemiluminescence type, there is a chemical sensor type NO concentration meter.
As a sensor for concentration detection, a semiconductor type, an electromotive force type, and a current detection type are known. Each of them has a characteristic such as a high response speed, and thus has an advantage that a measurement result can be measured instantaneously and easily. However, since the coexisting gas may affect the NO concentration indication value of the sensor, it is necessary to avoid the influence of such coexisting gas in order to apply the chemical sensor to NO concentration measurement of an actual machine. is there. Further, it is desired that such a chemical sensor be used for measuring NO ₂ and ammonia concentration (NH ₃ ) in addition to measuring NO concentration.

[0004] Therefore, in the conventional, NO _X analyzer in the flue gas as shown in FIG. 3 has been proposed.

[0005] As shown in FIG. 3, an exhaust gas 01 containing NO _X and NH ₃ is branched into two streams, and an ammonia oxidation catalyst 03 for oxidizing ammonia in a first stream 02A and a downstream of the ammonia oxidation catalyst 03. A first NO _x meter 04A for measuring NO _x concentration and a second measurement line 02
B, a first denitration catalyst 05 for denitration of NO _X
A second NO _x meter 04B, which is provided downstream of the denitration catalyst 05 and measures NO _x concentration, and a first NO _x meter 04A
And receiving the sensor output from the second of the NO _X meter 04B N
And an arithmetic unit 06 for calculating and measuring the Ox concentration and the NH ₃ concentration.

Next, using the apparatus shown in FIG.
A method for analyzing NOx in the gas will be described. Exhaust gas not shown
NO in exhaust gas 01 sampled from the duct_X
NO + NO as minutes_TwoIs a (ppm), NH_ThreeIs b (p
pm). This sampled exhaust gas 0
1 is branched into a first stream 02A and a second stream 02B
I do. Ammonia oxidation catalyst 03 is provided in first series 02A.
After passing, a first NOx analyzer 04 is installed, where N
O_XThe concentration is measured. On the other hand, in the second series 02B series
After passing through the denitration catalyst 05, the second NOx total 04B
Install, where NO _XThe concentration is measured.

[0007] Here, the total content of the conversion amount NOx measured value of the first of the NO _X meter 04A of the first series 02A is ammonia is converted to NO _X (bppm) and NO _X (appm) is measured. On the other hand, the second NO _X total 04 of the second series 02B
NOx measurements of B is, if NO _X concentration is higher than the ammonia concentration (a> b), the NO _X meter 04B, N
The O _X concentration can be measured correctly.

[0008]

However, NO _X
If the concentration is lower than the ammonia concentration (a <b), N
In O _X meter 04B, NO _X since only ammonia is consumed is introduced, it is impossible to measure the NO _X concentration. Therefore, in the apparatus as shown in FIG. 3, when the concentration of nitrogen oxide (NO _x ) is high, it can be measured normally,
For example, when there is a large amount of ammonia gas, such as when deep-denitration with ammonia is performed in a flue, there is a problem that normal measurement cannot be performed.

[0009]

Invention, nitrogen oxides in the exhaust gas in the first NOx and NH ₃ simultaneous analysis device in the exhaust gas of the present invention to solve the above problems SUMMARY OF THE INVENTION (NO _X) and ammonia (NH ₃₎ , A first measurement line and a second measurement line obtained by branching the exhaust gas into two lines, and an ammonia oxidation catalyst disposed on the first measurement line and oxidizing ammonia. When, it is disposed downstream of the ammonia oxidation catalyst, a first N measuring the NO _X concentration
And O _X meter, disposed in the second measurement line, a first denitration catalyst for the denitration of NO _X, after merging the exhaust gas of the first measurement line and the second measurement line, the combined gas a second denitration catalyst for the denitration of NO _X, are disposed downstream of the second denitration catalyst, and a second of the NO _X meter for measuring the NO _X concentration, first of the NO _X meter and the second of the NO _X characterized by comprising an arithmetic unit which receives the sensor output from the meter to calculate measures the NOx concentration and NH ₃ concentration.

A second invention is characterized in that, in the first invention, a NO ₂ meter for measuring the NO ₂ concentration in the exhaust gas is provided.

A third invention of a method for simultaneous analysis of NOx and NH ₃ in exhaust gas is a method for simultaneously measuring nitrogen oxides (NO _x ) and ammonia (NH ₃ ) in exhaust gas,
The exhaust gas is branched into two series of the first measurement line second measurement line, the ammonia is oxidized by the ammonia oxidation catalyst in a first measurement line, then, in the downstream of the ammonia oxidation catalyst, an NO _X concentration while measuring, in a second measurement line, is denitrating NO _X by the first denitration catalyst, then, after merging the exhaust gas of the first measurement line and the second measurement line, NO of combined gas
The _X is denitrification by the second denitration catalyst, in the second of the NO _X meter disposed downstream of the second denitration catalyst as measured by NO _X concentration, and a first of the NO _X meter and the second of the NO _X the NOx concentration and the NH ₃ concentration is calculated measured by computing unit receives the sensor output from the meter, and measuring the NO _X and the concentration of NH ₃ in the exhaust gas.

A fourth invention is characterized in that, in the third invention, the NO ₂ concentration in the exhaust gas is measured, and the NO and NO ₂ concentrations of NO _X and the NH ₃ concentration are measured.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

[0014] [First Embodiment] NOx and NH ₃ simultaneous analysis apparatus 10 according to this embodiment, the nitrogen oxides in the exhaust gas 11 sampled from a not-shown exhaust gas duct (NO _X) and ammonia (NH ₃ ) a first measuring line 12A and a second measuring line 12 for measuring the exhaust gas 11 by branching the exhaust gas 11 into two series.
And B, is disposed in the first measurement line 12A, and the ammonia oxidation catalyst 13 for oxidizing ammonia is provided downstream of the ammonia oxidation catalyst 13, first of the NO _X measuring the NO _X concentration meter 14 If, disposed in the second measurement line 12B, and the first denitration catalyst 15 for denitration of NO _X, after merging the exhaust gas of the first measurement line 12A and the second measurement line 12B, the confluence gas second for denitrating of the NO _X
And a denitration catalyst 16 is disposed downstream of the second denitration catalyst 16, a second of the NO _X meter 17 for measuring the NO _X concentration, first
And an arithmetic unit 18 which receives sensor outputs from the NO _X meter 14 and the second NO _X meter 17 to calculate and measure the NOx concentration and the NH ₃ concentration.

Here, the reaction represented by the formula (I) occurs in the ammonia oxidation catalyst 13 arranged in the first series 12A. 2NH ₃ + 5O 2 = 2NO + 3H 2 O (I) As the ammonia oxidation catalyst 13, for example, a catalyst in which Pt is supported on Al ₂ O ₃ as a carrier can be used. The present invention is not limited to such a catalyst.

Since the catalyst reaction temperature of the ammonia oxidation catalyst 13 is about 800 ° C., the catalyst 13 is heated to a reaction temperature by a heater. On the other hand, in the denitration catalyst 15 arranged in the second series 12B series, the reaction of the formula (II) occurs. 4NO + 4NH ₃ + O ₂ = 4N ₂ + 6H ₂ O (II) NH ₃ and O ₂ are contained in the exhaust gas. The above denitration catalyst 1
For 5, for example, a catalyst in which TiO ₂ is used as a carrier and V ₂ O ₅ is supported can be applied. In addition, it is not limited to this as long as it has the same catalytic ability. The catalyst reaction temperature is about 400 ° C
Therefore, the catalyst 15 is heated to the reaction temperature by the heater.

In the present invention, the first stream 12A, which the ammonia concentration is oxidized was the NO _X (bpp
m) and NO _x (a ppm) are the first NO _x
It is measured in a total of 14, whereas it is made SCR denitration second in series 12B NO _X, any of the NO _X or ammonia disappears. Thereafter, when the first stream 12A and the second series 12B are combined, since concentration of NO _X first series 12A (a + b) is high, even when the ammonia concentration of the second series 12B high, the NO _X concentration Can be measured. By applying the following formula based on this measurement result, the second NO _X meter 17 can measure accurately. Note that X
Is the flow rate of the first series 12A, and Y is the second series 12A.
B is the flow rate.

[X (a + b) + Y (ab)] / X + Y = A (1)

[0019] Thus, NOx measured value of the first of the NO _X meter 04A of the first series 02A and ammonia (BPPM) NO
The total amount with _X (a ppm) is measured. Meanwhile NOx measured value of the second of the NO _X meter 04B of the second series 02B is, NO
_{In both} cases where the _X concentration is higher than the ammonia concentration (a> b) and vice versa (a <b), NO _X and ammonia concentration can be simultaneously and normally measured.

[Second Embodiment] FIG. 2 shows an apparatus according to a second embodiment. As shown in FIG. 2, NOx and NH ₃ simultaneous analysis apparatus according to the embodiment 10
Are nitrogen oxides (NO _x ) and ammonia (N 2) in the exhaust gas 11 sampled from an exhaust gas duct (not shown).
A NO ₂ meter 19 for measuring the NO ₂ concentration in H ₃ ) is interposed before branching to measure the NO ₂ concentration. As the NO ₂ meter, a NO ₂ concentration meter such as a wet method can be used, but the present invention is not limited to this.

Thus, the NO concentration can be measured by subtracting the NO ₂ concentration from the NO _X concentration obtained in the first embodiment.

As a result, the ratio of NO and NO ₂ in the NO _X concentration and the ammonia concentration can be measured simultaneously.

[0023]

As described above, the first aspect of the present invention has been described.
According to Ming, nitrogen oxides (NO_X) And Ann
Monia (NH_Three) Is a device that simultaneously measures
Measurement line and second measurement line
Measurement line and the first measurement line
Ammonia oxidation catalyst for oxidizing near
NOx is provided downstream of the oxidation catalyst._XFirst to measure concentration
NO_XAnd the second measuring line_XTo
A first denitration catalyst for denitration, a first measurement line and a second
After merging the exhaust gas from the measurement line, the NO
_XA second denitration catalyst for denitrifying the gas, and a downstream of the second denitration catalyst
, And NO_XSecond NO to measure concentration_XAnd
The first NO_XTotal and second NO_XSensor output from the meter
NOx concentration and NH_ThreeA calculator that calculates and measures the concentration
And NO in the exhaust gas _XAnd NH_ThreeConcentration of
Can be measured. In particular, ammonia in exhaust gas
NO even when the amount of_XMeasurement of concentration
It becomes possible.

According to the second aspect of the present invention, since the first aspect of the present invention comprises the NO ₂ meter for measuring the NO ₂ concentration in the exhaust gas, the NO and NO ₂ concentrations and the NH ₃ concentration can be measured. .

NOx and NH in the third exhaust gas_ThreeSimultaneous
The invention of the precipitation method is based on the fact that nitrogen oxides (NO_X)as well as
Ammonia (NH_Three) At the same time,
Exhaust gas is divided into two lines, a first measurement line and a second measurement line.
At the first measurement line
Ammonia is oxidized by a medium, and then the ammonia
Downstream of the oxidation catalyst, NO_XWhen measuring the concentration
In the second measurement line, the first denitration catalyst
NO_X, And then the first measurement line and the second
After merging the exhaust gas from the measurement line, the NO
_XIs denitrified by the second denitration catalyst,
Second NO disposed downstream_XNO in total_XMeasured by concentration
And the first NO_XTotal and second NO_XSen from total
NOx concentration and NH_ThreeThe concentration is calculated by the arithmetic unit.
Calculation and measurement, NO in exhaust gas _XAnd NH_ThreeNo
The degree can be measured.

The fourth invention is, in the third invention, since measuring the NO ₂ concentration in the exhaust gas, NO _X in the NO and N
Concentrations and NH ₃ concentrations of O ₂ can be measured.

[Brief description of the drawings]

FIG. 1 shows NOx and NH _{3 according} to a first embodiment of the present invention.
It is the schematic of a simultaneous analyzer.

FIG. 2 is a schematic diagram of a NOx and NH ₃ simultaneous analyzer according to a second embodiment.

FIG. 3 is a schematic view of a conventional NOx and NH ₃ simultaneous analyzer.

[Explanation of symbols]

10 NOx and NH ₃ simultaneous analysis device 11 the exhaust gas 12A first measurement line 12B second measurement line 13 the ammonia oxidation catalyst 14 first of the NO _X meter 15 first denitration catalyst 16 second denitration catalyst 17 second NO _X total 18 arithmetic unit 19 NO ₂ total

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshio Koyanagi 1-1, Akunoura-cho, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries, Ltd. Nagasaki Shipyards (72) Inventor Akihiro Yamashita 2-5-1 Marunouchi, Chiyoda-ku, Tokyo (72) Inventor Keiko Kobayashi 2-5-1, Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 2G042 BA05 BB06 BB07 CA01 CB01 DA03 DA07 FB05 2G052 AA02 AB01 AB07 AC25 AD22 FB03 FD00 GA11 GA21 HB06 JA00

Claims (4)

[Claims] An apparatus for simultaneously measuring nitrogen oxides (NO _x ) and ammonia (NH ₃ ) in an exhaust gas, comprising: a first measurement line that branches the exhaust gas into two streams;
And measurement line, is disposed in the first measurement line, the ammonia oxidation catalyst for oxidizing ammonia is provided downstream of the ammonia oxidation catalyst, a first of the NO _X meter for measuring the NO _X concentration, and disposed in a second measurement line, a first denitration catalyst for the denitration of NO _X, after merging the exhaust gas of the first measurement line and the second measurement line, denitration of NO _X in the combined gas a second denitration catalyst is disposed downstream of the second denitration catalyst, and a second of the NO _X meter for measuring the NO _X concentration sensor output from the first of the NO _X meter and the second of the NO _X meter NOx and N of receiving by the exhaust gas, characterized by comprising a calculator for calculating measuring the NOx concentration and the NH ₃ concentration
H ₃ simultaneous analysis apparatus. 2. The method of claim 1, NOx and NH ₃ simultaneous analysis device in the exhaust gas characterized by comprising comprises a NO ₂ meter for measuring the NO ₂ concentration in the exhaust gas. 3. A method for simultaneously measuring nitrogen oxides (NO _x ) and ammonia (NH ₃ ) in exhaust gas, wherein the exhaust gas is branched into two lines, a first measurement line and a second measurement line. , ammonia is oxidized by the ammonia oxidation catalyst in a first measurement line, then, NO downstream of the ammonia oxidation catalyst, as well as measure the NO _X concentration in the second measurement line, the first denitration catalyst
_X is denitrified. After that, the exhaust gas of the first measurement line and the exhaust gas of the second measurement line are merged, and then NO _X in the merged gas is denitrated by the second denitration catalyst. measured by NO _X concentration in the second of the NO _X meter arranged, and computed by the computing unit of the NOx concentration and the NH ₃ concentration receives the sensor output from the first of the NO _X meter and the second of the NO _X meter measured, NOx and NH ₃ simultaneous analysis method in the exhaust gas and measuring the NO _X and the concentration of NH ₃ in the exhaust gas. 4. The method according to claim 3, wherein the NO ₂ concentration in the exhaust gas is measured, and NO and NO of NO _X are measured.
NOx and NH ₃ simultaneous analysis method in the exhaust gas and measuring the _second concentration and NH ₃ concentration.