JP2001188040A - So3 densitometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an SO3 densitometer capable of continuously measuring the density of SO3 in an exhaust gas. SOLUTION: A plurality of times for reciprocating light from a light source 9 is performed in a cavity 6 in which the exhaust gas is absorbed from a gas duct 1, and the density of SO3 in the exhaust gas can be measured by spectrally analyzing the light after going and returning by a calculation means. After the exhaust gas from the gas duct 1 is always absorbed into the cavity 6 to measure the density, the density of SO3 in the exhaust gas can be continuously measured since it is discharged to the gas duct 1. Dust leaks into the cavity 6 to diffuse the light from the light source 9 so as not to produce a measuring error since the dust can be removed in the case that the exhaust gas contains the dust by providing a filter 5 halfway of pieces of sucking piping 3a, 3b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention, SO ₃ for measuring the concentration of SO ₃ in the exhaust gas flue, such as combustion equipment continuously
It relates to a densitometer.

[0002]

2. Description of the Related Art Exhaust gas discharged from combustion equipment such as boilers and refuse incinerators contains harmful components such as sulfur oxides, and must be removed by a flue gas treatment device or the like. In addition, it is necessary to measure the concentration of sulfur oxides and the like in the exhaust gas discharged from the combustion equipment or the flue gas treatment device.

[0003] Here, SO ₂ is contained in sulfur oxides in exhaust gas.
And there are a SO _3, although in conventional flue gas treating apparatus is performing the removal of SO _2, the removal of SO ₃ is not performed, thus little has been done also measure the concentration of SO ₃ .

[0004] This is compared with the SO ₂ concentration in the exhaust gas.
_{3 Because the} concentration is low and the measurement is troublesome.

For the measurement of the concentration of SO ₃ gas, an acid condensation method, an isopropyl alcohol absorption method, a heated salt method, an ammonia injection method and the like are used.

(A) Acid Condensation Method When SO ₃ gas is contained in the exhaust gas, the acid dew point (condensation temperature) changes depending on the concentration thereof.
O ₃ is converted to sulfuric acid mist or the inner wall of the measuring tube (not shown)
This is a method in which the sample is condensed, collected, and measured by titration.
If the temperature of the inner wall of the measuring tube is set above the water dew point and below the acid dew point, the water in the exhaust gas will not condense, so other acid gases in the flue will not be condensed and the sulfuric acid mist will be condensed selectively. It is to take advantage of that.

[0007] As a method for collecting SO ₃ gas, a spiral tube is immersed in a constant temperature water bath, a measurement gas is flowed into the spiral tube, and SO ₃ in the gas is mist-condensed and condensed on the inner wall of the measurement tube. Collection method.

(B) Isopropyl alcohol absorption method Isopropyl alcohol utilizes the fact that SO ₃ gas is selectively dissolved and other gases in the flue are not dissolved.

As a method for collecting SO ₃ gas, 80% isopropyl alcohol is brought into contact with a measurement gas to absorb SO ₃ in exhaust gas. The carryover SO ₃ mist is collected by a glass filter and measured by titration.

(C) Heated salt method This is a method in which SO ₃ and NaCl are reacted to generate hydrochloric acid. Since the reaction between SO ₂ and NO _X and NaCl is considered to be small, SO ₃ can be selectively collected.

As a method for collecting SO ₃ gas, after removing moisture in the exhaust gas, the exhaust gas is caused to flow into a NaCl packed bed heated to 450 ° C. to absorb generated HCl in the water.
The concentration of SO ₃ gas is measured by titrating the HCl.

(D) Ammonia injection method This is a method in which NH ₃ is blown into a gas containing SO ₃ gas to form ammonium sulfate, and the SO ₃ concentration is estimated from the excess NH ₃ concentration.

[0013]

However, in the above-mentioned prior arts (a) to (d), it is difficult to continuously measure the concentration of SO ₃ in exhaust gas in a flue of a combustion facility or the like. was there.

It is an object of the present invention to solve the above-mentioned problems and to provide an SO ₃ concentration meter capable of continuously measuring the concentration of SO ₃ in exhaust gas.

[0015]

SO ₃ concentration meter of the present invention in order to achieve the above object, according to an aspect of is an SO ₃ concentration meter for measuring the concentration of SO ₃ in the exhaust gas flue, such as combustion equipment,
A cavity having an intake pipe for inhaling exhaust gas from the flue and an exhaust pipe for exhausting exhaust gas to the flue, a cavity having two opposed transparent windows, a light source for irradiating light into the cavity, A reflection mirror disposed outside and configured to reciprocate the light from the light source into and out of the cavity a plurality of times, and a calculating unit configured to calculate the concentration of SO _{3 in} the exhaust gas by spectrally analyzing the light after the reciprocation. It is.

In addition to the above configuration, the SO ₃ concentration meter of the present invention
It is preferable to provide a filter for removing dust in the exhaust gas in the middle of the suction pipe.

In addition to the above configuration, the SO ₃ concentration meter of the present invention
It is preferable to provide a pump for forcibly discharging the exhaust gas in the cavity into the flue in the middle of the discharge pipe.

In addition to the above configuration, the SO ₃ concentration meter of the present invention
It is preferable to provide a heater for heating the cavity.

According to the present invention, the SO ₃ concentration in the exhaust gas is measured by causing the light from the light source to reciprocate a plurality of times into the cavity into which the exhaust gas has been sucked from the flue, and spectrally analyzing the light after the reciprocation. Can be. Since the flue gas from the flue is always sucked into the cavity and the concentration is measured and then discharged into the flue, the concentration of SO _{3 in} the flue gas can be continuously measured. In addition, by providing a filter in the middle of the suction pipe, dust can be removed if the exhaust gas contains dust, so that dust enters the cavity and scatters light from the light source, causing measurement errors. I will not let you. In addition, by installing a pump in the exhaust pipe for forcibly discharging the exhaust gas in the cavity to the flue, the exhaust gas is always sucked into the cavity without decreasing the flow velocity of the exhaust gas flowing in the flue, and the concentration measurement is performed. Since the exhaust gas is discharged to the rear flue, the exhaust gas does not stay in the cavity.

[0020]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram showing an embodiment of an SO ₃ concentration meter according to the present invention.

In FIG. 1, reference numeral 1 denotes a flue of a combustion facility or the like. One end (suction port) of a suction pipe 3a is mounted on the upstream side of the flue 1 in which exhaust gas flows in the direction of arrow 2, and one end (discharge port) of a discharge pipe 4a is mounted on the downstream side of the flue 1. ing. The other end of the suction pipe 3a is connected to a suction port 5a of a filter 5 (for example, a container filled with glass wool).
The outlet 5b of the filter 5 is connected to the suction pipe 3b.
Is connected to the suction port 6a of the cavity 6 through the opening.
The discharge port 6b of the cavity 6 is connected to the suction port 7a of the pump 7 via the discharge pipe 4b. The discharge port 7b of the pump 7 is connected to the other end of the discharge pipe 4a.

The cavity 6 is a substantially cylindrical closed container,
It has transparent windows 8a and 8b made of two opposing transparent members (for example, quartz glass).

A light source (for example, a xenon lamp) 9 and a spectroscope 10 are provided on one end face side (the left side in the figure) of the cavity 6.
And are arranged.

A plurality of reflection mirrors 11 a and 11 are provided on both end surfaces of the cavity 6 so that light emitted from the light source 9 reciprocates in the cavity 6 a plurality of times and then enters the spectroscope 10.
b and 11c are arranged. These cavities 6
The transparent windows 8a and 8b and the reflection mirrors 11a to 11c form a multi-pass cell.

The spectroscope 10 is provided with a light detecting element (for example, a photodiode) 12 that receives the light separated after reciprocating in the cavity 6 and converts the light into an electric signal. An arithmetic unit (for example, a personal computer) 13 that calculates the SO ₃ concentration in the exhaust gas (for example, performs a multivariate analysis) based on a signal from the light detection element 12 is connected to the light detection element 12. The spectroscope 10, the light detecting element 12, and the arithmetic unit 13 constitute a calculating unit.

A heater 15 whose temperature is controlled by a temperature controller 14 is disposed in the cavity 6. The heater 15 converts the exhaust gas sucked into the cavity 6 to 350 ° C.
By heating to a temperature of 450 ° C. or lower, SO _{3 in} the exhaust gas is prevented from becoming sulfuric acid gas or being decomposed into SO _2, and the accuracy of concentration measurement is improved.

With this SO ₃ concentration meter configured in this manner, the exhaust gas in the flue 1 passes through the suction pipes 3a and 3b through the arrows 1
Light from the light source 9 reciprocates into the cavity 6 sucked in six directions. The light that has reciprocated in the cavity 6 is absorbed by the SO ₃ gas concentration, is separated by the spectroscope 10, is received by the light detection element 12, and is calculated by the calculation device 13, thereby obtaining the SO ₃ concentration.

In the cavity 6 for optically measuring the concentration of SO _{3, the} exhaust gas is always supplied from the flue 1 to the suction pipe 3.
a and 3b are sucked in the direction of arrow 16 and the concentration is measured.
Therefore, the concentration of SO _{3 in} the exhaust gas can be continuously measured.

Also, since the filter 5 for removing dust in the exhaust gas is provided in the middle of the suction pipes 3a and 3b, dust enters the cavity 6 and the measurement error due to the scattering of light from the light source 9 is reduced. Will not cause. Furthermore, since the pump 7 for forcibly discharging the exhaust gas in the cavity 6 into the flue 1 is provided in the middle of the discharge pipes 4a and 4b, the flow rate of the exhaust gas flowing in the flue 1 may be reduced. Since the exhaust gas is always sucked into the cavity 6 and discharged to the flue 1, the exhaust gas does not stay in the cavity 6. Further, since the reflection mirrors 11a to 11c are arranged outside the cavity 6, there is no corrosion of the reflection mirrors 11a to 11c due to exhaust gas.

Next, description will be made with specific numerical values, but the present invention is not limited to these numerical values.

FIG. 2 is a diagram showing an absorption spectrum of SO ₃ measured using the SO ₃ concentration meter shown in FIG. 1. The horizontal axis indicates the wavelength axis, and the vertical axis indicates the transmittance.

A straight line L0 indicates light from the light source, and a curve L1
Shows the characteristics when the SO ₃ concentration is 95 ppm, and the curve L
2 shows the characteristics when the SO ₃ concentration is 289 ppm, and the curve L3 shows the characteristics when the SO ₃ concentration is 474 ppm. SO ₃ concentration is represented the spectrum due to differences in, the SO ₃ SO smoke journey exhaust gas by densitometer ₃
Can be measured.

The temperature of the cavity through which the exhaust gas passed was 300 ° C., and the length of the cavity was 1 m.

FIG. 3 is a diagram showing the results of measuring the SO ₂ spectrum and the SO ₃ spectrum using the SO ₃ densitometer shown in FIG. 1. The horizontal axis represents the wavelength axis, and the vertical axis represents the transmission. Shows the rate.

From the figure, it can be seen that the SO ₂ spectrum and the SO ₃ spectrum are separated in the wavelength range of 200 nm to 260 nm, particularly 230 nm to 260 nm, so that the concentration of SO ₃ can be measured by spectroscopic analysis.

Accordingly, it can be seen that when measuring the light from the cavity by spectroscopic analysis, it is preferable to use light (ultraviolet light) having a wavelength of 200 nm to 260 nm.

FIG. 4 is a calibration curve graph when the SO ₃ concentration meter shown in FIG. 1 is used. The horizontal axis indicates the adjusted SO ₃ concentration axis, and the vertical axis indicates the absorbance axis.

The graph shows a cell (cavity) having a length of 1 m.
And obtained by simple regression analysis under the condition of 230 ° C., and the calibration curve graph is represented by Formula 1.

[0040]

Y = 0.0001x + 0.0059 where the multiple correlation coefficient R ² is 0.9795.

By using this calibration curve graph, the concentration of SO ₃ in the flue gas in the flue can be determined from the absorbance.

FIG. 5 is a conceptual diagram showing another embodiment of the SO ₃ concentration meter according to the present invention. Hereinafter, the same members as those of the embodiment shown in FIG.

The difference from the embodiment shown in FIG. 1 is that a heating furnace 18 is arranged so as to cover the cavity 6.

That is, in the present SO ₃ concentration meter, suction pipes 3 a and 3 b for sucking exhaust gas are attached upstream of the flue 1, and a discharge pipe for discharging the sucked exhaust gas to the flue 1. 4a and 4b are mounted on the downstream side of the flue 1 and a cavity 6 having transparent windows 8a and 8b through which light passes, a heating furnace 18 arranged to cover the cavity 6, and a heating furnace 18 Temperature controllers 19 and 20 for controlling the temperature within a range of 350 ° C. to 450 ° C., a light source 9 for irradiating light into the cavity 6, and a light source 9 disposed outside the cavity 6 and transmitting light from the light source 9 to the cavity 6. Mirrors 21a to 21h for reciprocating a plurality of times in the interior,
A spectroscope 10 that splits the light reflected by the reflection mirrors 21a to 21h, a photodetector 12 that receives the light split by the spectrometer 10, and a concentration of SO _{3 in} exhaust gas based on a signal from the photodetector 12 And an arithmetic unit 13 for calculating Reference numeral 22 denotes a slit for blocking extra light from the light from the light source 9.

The SO ₃ can be measured the concentration of SO ₃ in SO ₃ concentration meter as well as in the exhaust gas is also shown in FIG. 1 in such a SO ₃ concentration meter continuously shown in FIG. 1
Since the temperature in the cavity 6 is controlled to be uniform as compared with the densitometer, the measurement accuracy is high.

FIG. 6 is a graph showing the relationship between the composition of SO ₃ , the concentration of water, and the temperature. The horizontal axis indicates the concentration axis of water, and the vertical axis indicates the composition axis of SO ₃ . .

It can be seen from the figure that at a temperature of 350 ° C. or lower, the composition of SO ₃ decreases as the concentration of water increases.
That is, to become sulfuric acid gas combines with water vapor in SO ₃ is 350 ° C. or less of the temperature, it is impossible to measure the concentration, composition of SO ₃ also increases the concentration of water at 350 ° C. or higher temperatures It turns out that it does not change much. However, SO ₃ is decomposed into SO ₂ at a temperature of 450 ° C. or higher, so that the concentration cannot be measured. For this reason,
It is necessary to keep the temperature of the exhaust gas at 350 ° C. or more and 450 ° C. or less.

However, in this embodiment, since the temperature in the cavity 6 is controlled by the temperature controllers 19 and 20 and the heating furnace 18 so as to be 350 ° C. to 450 ° C., SO ₃ in the cavity 6 is decomposed, The concentration can be accurately measured without becoming sulfuric acid gas. Also,
Since the reflection mirrors 21a to 21h are arranged outside the cavity 6, there is no corrosion of the reflection mirrors 21a to 21h.

FIG. 7 is a conceptual diagram showing a sulfuric acid gas concentration meter using the SO ₃ concentration meter of the present invention.

The difference from the embodiment shown in FIG.
A preheating unit whose temperature is adjusted by a temperature controller is provided in the suction pipe of the cavity of the O ₃ concentration meter, and not only the concentration of SO ₃ but also the concentration of sulfuric acid gas can be measured.

That is, the present sulfuric acid gas concentration meter has suction pipes 3a, 3b, 3c for sucking exhaust gas from the flue 1 and discharge pipes 4a, 4b for discharging exhaust gas to the flue 1, and are opposed to each other. A cavity 6 having two transparent windows 8a and 8b, a preheating section 23 provided between the suction pipes 3b and 3c for preheating exhaust gas passing through the suction pipes 3a to 3c, and a preheating chamber 23a of the preheating section 23. Temperature of 400
A temperature controller 24 for adjusting the temperature of the heater 23b so as to be equal to or higher than 450 ° C. and a light source 9 for irradiating light into the cavity 6;
Reflection mirrors 11a to 11c for reciprocating the light from the light source 9 into the cavity 6 a plurality of times, and reflection mirrors 11a to 11c.
A spectroscope 10 that splits the light reflected by 11c, a photodetector 12 that receives light from the spectroscope 10, and a photodetector 1
The SO ₃ concentration in the exhaust gas is determined based on the signal from
An arithmetic unit 2 for calculating the sulfuric acid gas concentration from the SO ₃ concentration
5.

In such a sulfuric acid gas concentration meter, FIG.
As in the case of the SO ₃ concentration meter shown in (1), the concentration of SO ₃ in the exhaust gas and the concentration of sulfuric acid gas can be continuously measured.

Here, SO ₃ in the flue 1 exists as sulfuric acid gas at a low temperature, and the SO ₃ concentration meter using ultraviolet spectroscopy does not absorb sulfuric acid gas, so that the concentration measurement cannot be performed as it is. However, the sulfuric acid gas concentration meter changes the sulfuric acid gas to SO ₃ by heating the sulfuric acid gas to a temperature of 400 ° C. or more and 450 ° C. or less,
By obtaining the _three concentrations, the sulfuric acid gas concentration can be measured continuously but indirectly.

That is, the preheating section 23 for preheating the exhaust gas in the suction pipes 3a to 3c, and the temperature of the preheating section 23 is 400 ° C.
A temperature controller 24 that adjusts the temperature to 450 ° C. or lower.
Thus, the sulfuric acid gas concentration can be measured by changing the sulfuric acid gas in the exhaust gas to SO ₃ .

In the present sulfuric acid gas concentration meter, the size of the preheating section 23 may be changed according to the decomposition rate of the sulfuric acid gas.
In the present sulfuric acid gas concentration meter, under conditions where sulfuric acid gas and SO ₃ are mixed, a concentration obtained by adding both is obtained.

FIG. 8 is a conceptual diagram of an exhaust gas sampling device showing a modification of the filter used in the SO ₃ concentration meter of the present invention. FIG. 9 is a diagram showing a state in which the exhaust gas sampling device shown in FIG. 8 is attached to a flue of a combustion facility.

While the filter 5 shown in FIGS. 1, 5 and 7 has a container filled with glass wool, the exhaust gas sampling device 26 converts exhaust gas containing dust discharged from combustion equipment or the like into exhaust gas. An exhaust gas sampling device for sampling only, wherein a suction port 27a is connected to an upstream side of the flue 1 of the combustion equipment and a discharge port 27b is connected to a downstream side of the flue 1; And a substantially cylindrical filter 28 having an inner wall having substantially the same cross-sectional shape as the duct 27, and a takeout port 29a for covering the outside of the filter 28 and taking out the filtered exhaust gas.
And a cover 29 having the same.

The duct 27 is provided with a pump 30 for sucking exhaust gas containing dust from the flue 1 and forcibly discharging the exhaust gas into the flue 1.

This sampling device is connected to the SO shown in FIG.
_When used for a ₃ concentration meter, after removing the suction pipe 3a and the filter 5 of the SO ₃ concentration meter, the suction port and the discharge port of the duct 27 are attached to the flue 1, and the extraction port 29a is connected to the suction pipe 3b. What is necessary is just to mount (in this case, two pumps 7 and 30 will be used).

According to this exhaust gas sampling apparatus, since the shape of the filter 28 is substantially cylindrical having substantially the same cross-sectional shape as that of the duct 27, the dust-containing exhaust gas blocks the flow when flowing in the filter 28 in the direction of arrow 31. Even if the dust 32 adheres to and accumulates on the inner wall of the filter 28 due to low resistance, the dust 28 is pushed by the flow of the exhaust gas and returns to the flue 1 again through the duct 27, so that the filter 28 is almost clogged. Absent. The SO ₃ gas in the exhaust gas sucked into the duct 27 passes through the filter 28 through an arrow 33.
Outlet 29 formed in cover 29 passing through
a to the cavity 6 in the direction of the arrow 34.

Since the pump 27 for sucking the exhaust gas from the flue 1 and forcibly discharging the exhaust gas into the flue 1 is inserted into the duct 27, the exhaust gas flowing in the duct 27 in the directions of arrows 35 and 36 is inserted. Filter 2 without decreasing the flow rate of
The dust 32 adhering to the stack 8 is forcibly removed and the flue 1
And the filter 28 is hardly clogged.

[0062]

In summary, according to the present invention, the following excellent effects are exhibited.

It is possible to provide an SO ₃ concentration meter capable of continuously measuring the concentration of SO ₃ in exhaust gas.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an embodiment of an SO ₃ concentration meter according to the present invention.

FIG. 2 shows S measured using the SO ₃ concentration meter shown in FIG.
Absorption spectra of O ₃ is a diagram showing a.

FIG. 3 is a diagram showing a result of measuring an SO ₂ spectrum and an SO ₃ spectrum using the SO ₃ concentration meter shown in FIG. 1;

FIG. 4 is a calibration curve graph when the SO ₃ concentration meter shown in FIG. 1 is used.

FIG. 5 is a conceptual diagram showing another embodiment of the SO ₃ concentration meter of the present invention.

FIG. 6 is a diagram showing the relationship between the composition of SO ₃ , the concentration of water, and the temperature.

FIG. 7 is a conceptual diagram showing a sulfuric acid gas concentration meter using the SO ₃ concentration meter of the present invention.

FIG. 8 is a conceptual diagram of an exhaust gas sampling device showing a modification of the filter used in the SO ₃ concentration meter of the present invention.

9 is a diagram showing a state in which the exhaust gas sampling device shown in FIG. 8 is attached to a flue of a combustion facility.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flue 5 Filter 6 Cavity 7 Pump 8a, 8b Transparent window 9 Light source 10 Spectrometer 11a-11c Reflection mirror 12 Photodetector 13 Computing device

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01N 31/00 G01N 31/00 P (72) Inventor Kohei Suzuki 1 Shinnakaharacho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Ishikawashima Harima Heavy Industries, Ltd. Machine and Plant Development Center F-term (reference)

Claims (4)

[Claims] 1. SO _{3 in} flue gas in a flue such as a combustion facility
A SO ₃ concentration meter for measuring the concentration of air, comprising a suction pipe for sucking exhaust gas from the flue and a discharge pipe for discharging exhaust gas to the flue, and a cavity having two opposed transparent windows. A light source for irradiating light into the cavity, a reflection mirror disposed outside the cavity to reciprocate light from the light source into the cavity a plurality of times, and spectrally analyzing the reciprocated light. SO ₃ concentration meter, characterized in that a calculation means for calculating the concentration of SO ₃ in said exhaust gas by. 2. A filter according to claim 1, wherein a filter for removing dust in the exhaust gas is provided in the suction pipe.
O ₃ densitometer. _3. The SO ₃ concentration meter according to claim 2, wherein a pump for forcibly discharging exhaust gas in the cavity into the flue is provided in the middle of the discharge pipe. 4. The SO ₃ concentration meter according to claim 3, wherein a heater for heating the cavity is provided in the cavity.