JP4206592B2 - SO3 densitometer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an SO ₃ concentration meter that continuously measures the concentration of SO ₃ in exhaust gas in a flue of a combustion facility or the like.
[0002]
[Prior art]
Since exhaust gas discharged from combustion facilities such as boilers and garbage incinerators contains harmful components such as sulfur oxides, it is necessary to remove them with a flue gas treatment device or the like. In addition, it is necessary to measure the concentration of sulfur oxides in the exhaust gas discharged from the combustion facility or the flue gas treatment device.
[0003]
Here, the sulfur oxides in the exhaust gas is the SO ₂ and SO _3, although in conventional flue gas treating apparatus is performing the removal of SO _2, prior to the removal of SO ₃ is not performed Therefore, the measurement of SO ₃ concentration has not been carried out much.
[0004]
Since this is a low SO ₃ concentration than the SO ₂ concentration in the exhaust gas, or difficult to measure, in order to or become troublesome.
[0005]
For such SO ₃ gas concentration measurement, an acid condensation method, an isopropyl alcohol absorption method, a heated salt method, an ammonia injection method, or the like is used.
[0006]
(a) The inclusion of SO ₃ gas to the acid condensation method in the exhaust gas, since the acid dew point (condensation temperature) varies depending on the concentration, without the SO ₃ in the exhaust gas was the inner wall (shown in sulfuric acid mist reduction or measuring tubes ) And then collected by titration and measured by titration. If the temperature of the inner wall of the measuring tube is set to the water dew point or more and the acid dew point or less, the moisture in the exhaust gas will not condense, so other acid gases in the flue will not be condensed, and sulfuric acid mist will be condensed selectively. Is to use 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 allowed to flow through the spiral tube, and SO ₃ in the gas is misted and condensed on the inner wall of the measurement tube and collected. Is mentioned.
[0008]
(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.
[0009]
As a method for collecting SO ₃ gas, 80% isopropyl alcohol and measurement gas are brought into contact with each other to absorb SO ₃ in the exhaust gas. Carryover SO ₃ mist is collected with a glass filter and measured by titration.
[0010]
(c) Heated sodium salt method In this method, hydrochloric acid is produced by reacting SO ₃ with NaCl. Since there is little reaction between SO ₂ , NO _x and NaCl, SO ₃ can be selectively collected.
[0011]
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., and the generated HCl is absorbed by water. The SO ₃ gas concentration is measured by titrating the HCl.
[0012]
(d) Ammonia injection method In this method, 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]
[Problems to be solved by the invention]
However, the conventional techniques (a) to (d) described above have a problem that it is difficult to continuously measure the concentration of SO _{3 in} the exhaust gas in the flue of a combustion facility or the like.
[0014]
Accordingly, an object of the present invention is to solve the above-described problems and provide an SO ₃ concentration meter that can continuously measure the concentration of SO ₃ in exhaust gas.
[0015]
[Means for Solving the Problems]
SO ₃ concentration meter of the present invention in order to achieve the above object, a SO ₃ concentration meter for measuring the concentration of SO ₃ in the exhaust gas that contains SO ₂ and SO ₃ in flue such as combustion equipment, the It has a suction pipe for sucking exhaust gas from the flue and a discharge pipe for discharging exhaust gas to the flue, and has a cavity having two transparent windows facing each other, and the temperature of the exhaust gas sucked into the cavity is 350 ° C. A heater for heating so as to keep the temperature at ˜450 ° C., a light source for irradiating light in the cavity, and a light source disposed outside the cavity to reciprocate the light from the light source into the cavity a plurality of times. And a calculating means for calculating the SO ₃ concentration in the exhaust gas by spectroscopically analyzing light having a wavelength of 200 nm to 260 nm among the light after reciprocation. The SO ₃ concentration meter of the present invention may further include a preheating unit that is provided between the cavity and the suction pipe and preheats exhaust gas that passes through the suction pipe.
[0016]
In addition to the above configuration, the SO ₃ concentration meter of the present invention is preferably provided with a filter for removing dust in the exhaust gas in the middle of the suction pipe.
[0017]
In addition to the above configuration, the SO ₃ concentration meter of the present invention is preferably provided with a pump for forcibly discharging the exhaust gas in the cavity to the flue in the middle of the discharge pipe.
[0019]
According to the present invention, the SO ₃ concentration in the exhaust gas can be measured by reciprocating the light from the light source a plurality of times into the cavity into which the exhaust gas has been sucked from the flue and performing spectral analysis of the light after the reciprocation. Since the exhaust gas from the flue is always inhaled into the cavity and the concentration is measured and then discharged to the flue, the SO ₃ concentration in the exhaust gas can be continuously measured.
[0020]
Further, according to the present invention, the spectrum of SO _{2 and} the spectrum of SO ₃ are obtained by spectroscopically analyzing the light having a wavelength of 200 nm to 260 nm among the light after reciprocating in the cavity and calculating the SO ₃ concentration in the exhaust gas. Can be separated from each other and is not affected by water absorption, so that an accurate SO ₃ concentration can be obtained.
[0021]
In addition, by providing a filter in the middle of the suction pipe, dust can be removed when the exhaust gas contains dust, so that dust enters the cavity and scatters light from the light source, resulting in measurement errors. I will not let you. Furthermore, by providing a pump that forcibly discharges the exhaust gas in the cavity to the flue in the middle of the discharge pipe, the exhaust gas is always inhaled into the cavity without reducing the flow rate of the exhaust gas flowing in the flue. Since the exhaust gas is discharged to the flue after the concentration measurement, the exhaust gas does not stay in the cavity.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0023]
FIG. 1 is a conceptual diagram showing an embodiment of an SO ₃ concentration meter according to the present invention.
[0024]
In the figure, reference numeral 1 denotes a flue such as a combustion facility. One end (suction port) of the suction pipe 3a is attached to the upstream side of the flue 1 where the exhaust gas flows in the direction of the arrow 2, and one end (discharge port) of the discharge pipe 4a is attached to the downstream side of the flue 1. ing. The other end of the suction pipe 3a is connected to the suction port 5a of the filter 5 (for example, a container filled with glass wool), and the discharge port 5b of the filter 5 is connected to the suction port 6a of the cavity 6 via the suction pipe 3b. It is connected to the. The discharge port 6b of the cavity 6 is connected to the suction port 7a of the pump 7 through the discharge pipe 4b. The discharge port 7b of the pump 7 is connected to the other end of the discharge pipe 4a.
[0025]
The cavity 6 is a substantially cylindrical sealed container, and has transparent windows 8a and 8b made of two transparent members (for example, quartz glass) facing each other.
[0026]
A light source (for example, a xenon lamp) 9 and a spectroscope 10 are arranged on one end face side (left side in the figure) of the cavity 6.
[0027]
A plurality of reflection mirrors 11 a, 11 b, and 11 c are arranged 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 enters the spectroscope 10. These cavities 6, transparent windows 8a and 8b, and reflecting mirrors 11a to 11c constitute a multi-pass cell.
[0028]
The spectroscope 10 is provided with a light detection element (for example, a photodiode) 12 that receives the light that has been dispersed after reciprocating in the cavity 6 and converts it into an electrical signal. An arithmetic unit (for example, a personal computer) that calculates the SO ₃ concentration in exhaust gas (performs multivariate analysis) based on a signal corresponding to light having a wavelength of 200 nm to 260 nm among signals from the photodetection element 12. 13 is connected. The spectroscope 10, the light detection element 12, and the arithmetic unit 13 constitute a calculation means.
[0029]
A heater 15 whose temperature is controlled by a temperature regulator 14 is disposed in the cavity 6. The heater 15 heats the exhaust gas sucked into the cavity 6 so that the temperature becomes 350 ° C. or higher and 450 ° C. or lower, so that SO _{3 in} the exhaust gas becomes sulfuric acid gas or decomposes into SO ₂ . Is prevented and the accuracy of concentration measurement is improved.
[0030]
By configuring the SO ₃ concentration meter in this way, the light from the light source 9 reciprocates into the cavity 6 in which the exhaust gas in the flue 1 is sucked in the suction pipes 3a and 3b in the direction of arrow 16. The light reciprocating in the cavity 6 is absorbed by the SO ₃ gas concentration, separated by the spectroscope 10, received by the light detection element 12, and calculated by the calculation device 13, thereby obtaining the SO ₃ concentration in the exhaust gas. .
[0031]
According to the present SO ₃ densitometer, the SO ₂ spectrum and the SO ₃ spectrum are calculated by calculating the SO ₃ concentration based on a signal corresponding to light having a wavelength of 200 nm to 260 nm among the light emitted from the spectrometer 10. Can be separated from each other and is not affected by water absorption, so that an accurate SO ₃ concentration can be obtained.
[0032]
In the cavity 6 for optically measuring the SO ₃ concentration, exhaust gas is always drawn from the flue 1 through the suction pipes 3a and 3b in the direction of the arrow 16 and the concentration is measured, and then the discharge pipes 4a and 4b are shown by the arrow 17 Since it is discharged to the flue 1 in the direction, the concentration of SO _{3 in} the exhaust gas can be continuously measured.
[0033]
Further, 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 scatters light from the light source 9 to cause a measurement error. There is nothing. Furthermore, since the pump 7 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 inhaled into the cavity 6 and the concentration is measured and then discharged into the flue 1, the exhaust gas does not stay in the cavity 6. 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.
[0034]
Next, specific numerical values will be described. However, the present invention is not limited to them.
[0035]
FIG. 2 is a diagram showing an absorption spectrum of SO ₃ measured using the SO ₃ densitometer shown in FIG. 1, with the horizontal axis indicating the wavelength axis and the vertical axis indicating the transmittance.
[0036]
A straight line L0 indicates light from the light source, a curve L1 indicates characteristics when the SO ₃ concentration is 95 ppm, a curve L2 indicates characteristics when the SO ₃ concentration is 289 ppm, and a curve L3 indicates when the SO ₃ concentration is 474 ppm. The characteristics are shown. The spectrum by the difference in SO ₃ concentration is shown, and it can be seen that the SO ₃ concentration meter can measure the concentration of SO ₃ in the flue gas in the flue.
[0037]
The cavity temperature was 300 ° C., and the cavity length was 1 m.
[0038]
FIG. 3 is a diagram showing the results of measuring the SO ₂ spectrum and the SO ₃ spectrum using the SO ₃ concentration meter shown in FIG. 1. The horizontal axis indicates the wavelength axis, and the vertical axis indicates the transmittance. ing.
[0039]
From the figure, it can be seen that the SO ₃ spectrum and the SO ₂ 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.
[0040]
Accordingly, when measuring light from the cavity by spectroscopic analysis, it is preferable to use light having a wavelength of 200 nm to 260 nm.
[0041]
FIG. 4 is a calibration curve graph when the SO ₃ concentration meter shown in FIG. 1 is used. The horizontal axis represents the adjusted SO ₃ concentration axis, and the vertical axis represents the absorbance axis.
[0042]
The graph is obtained by single regression analysis using a cell having a length of 1 m under a condition of 230 ° C., and a calibration curve graph is expressed by the following equation (1).
[0043]
[Expression 1]
y = 0.0001x + 0.0059
However, the multiple correlation coefficient R ² is 0.9795.
[0044]
By using this calibration curve graph, the SO ₃ concentration can be determined from the absorbance.
[0045]
FIG. 5 is a conceptual diagram showing another embodiment of the SO ₃ concentration meter of the present invention. In addition, the same code | symbol was used for the member similar to embodiment shown in FIG.
[0046]
The difference from the embodiment shown in FIG. 1 is that a heating furnace 18 is arranged so as to cover the cavity 6.
[0047]
That is, the present SO ₃ concentration meter, the SO ₃ concentration meter, suction pipe 3a for sucking the exhaust gas, 3b is mounted on the upstream side of the flue 1, for discharging the sucked gas in the flue 1 The discharge pipes 4a and 4b are attached to the downstream side of the flue 1, and the cavity 6 in which transparent windows 8a and 8b through which light passes are formed, and the heating furnace 18 arranged so as to cover the cavity 6, Temperature controllers 19 and 20 for controlling the temperature of the heating furnace 18 within a range of 350 ° C. to 450 ° C., a light source 9 for irradiating light into the cavity 6, an outside of the cavity 6, Reflective mirrors 21a to 21h for allowing light to reciprocate in the cavity 6 a plurality of times, a spectroscope 10 for splitting the light reflected by the reflective mirrors 21a to 21h, and a photodetector for receiving the light split by the spectroscope 10 12, Based on a signal from the light detection element 12 is obtained is constituted by an arithmetic unit 13 for calculating the SO ₃ concentration in the exhaust gas. Reference numeral 22 denotes a slit for blocking excess light from the light from the light source 9.
[0048]
Such SO ₃ concentration of SO ₃ in SO ₃ concentration meter as well as in the exhaust gas is also shown in FIG. 1 in densitometer can be continuously measured, compared with the SO ₃ concentration meter shown in FIG. 1 Since the temperature in the cavity 6 is controlled to be uniform, the measurement accuracy is high.
[0049]
Here, FIG. 6 is a diagram showing the relationship between the SO ₃ composition, the water concentration, and the temperature. The horizontal axis indicates the water concentration axis, and the vertical axis indicates the SO ₃ composition axis.
[0050]
From the figure, it can be seen that at a temperature of 350 ° C. or lower, the SO ₃ composition decreases as the concentration of water increases. That is, SO ₃ combines with water vapor at a temperature of 350 ° C. or lower to form sulfuric acid gas, so the concentration cannot be measured. However, at a temperature of 350 ° C. or higher, the composition of SO ₃ does not increase even if the water concentration increases. It turns out that it does not change so much. However, since SO ₃ decomposes into SO ₂ at a temperature of 450 ° C. or higher, the concentration cannot be measured. For this reason, it is necessary to maintain the temperature of exhaust gas at 350 ° C. to 450 ° C.
[0051]
However, in this embodiment, since the temperature in the cavity 6 is controlled to 350 ° C. to 450 ° C. by the temperature controllers 19 and 20 and the heating furnace 18, the SO ₃ in the cavity 6 is decomposed or converted into sulfuric acid gas. Therefore, it is possible to measure accurately. Further, since the reflection mirrors 21a to 21h are arranged outside the cavity 6, the reflection mirrors 21a to 21h are not corroded.
[0052]
FIG. 7 is a conceptual diagram showing a sulfuric acid gas concentration meter using the SO ₃ concentration meter of the present invention.
[0053]
The difference from the embodiment shown in FIG. 1 is that a preheating part in which the temperature is adjusted by a temperature controller is provided in the suction pipe of the cavity of the SO ₃ concentration meter, and only the concentration of SO ₃ is provided. In addition, the concentration of sulfuric acid gas can be measured.
[0054]
That is, the 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 two transparent windows facing each other. The temperature in the preheating chamber 23a of the preheating section 23 of the cavity 6 having 8a and 8b, the preheating portion 23 provided between the intake pipes 3b and 3c for preheating the exhaust gas passing through the intake pipes 3a to 3c is 400. A temperature adjuster 24 that adjusts the temperature of the heater 23b so that the temperature is higher than or equal to 450 ° C. and lower than or equal to 450 ° C., a light source 9 for irradiating light into the cavity 6, and an outside of the cavity 6, and Reflecting mirrors 11a to 11c for reciprocating in the cavity 6 a plurality of times, a spectroscope 10 for splitting the light reflected by the reflecting mirrors 11a to 11c, and a light detecting element 1 for receiving the light from the spectroscope 10. When obtains the SO ₃ concentration in the exhaust gas based on a signal from the light detection element 12, in which is constituted by from the SO ₃ concentration calculation unit 25 for calculating the sulfuric acid gas concentration.
[0055]
In such a sulfuric acid gas concentration meter, the concentration of SO _{3 and} the concentration of sulfuric acid gas in the exhaust gas can be continuously measured as in the SO ₃ concentration meter shown in FIG.
[0056]
Here, SO ₃ exists in the flue 1 as sulfuric acid gas at a low temperature, and the SO ₃ analyzer based on ultraviolet spectroscopy does not absorb sulfuric acid gas, so the concentration cannot be measured as it is. However, the present acid gas concentration meter is varied SO ₃ by heating so that a temperature of below 450 ° C. 400 ° C. or higher sulfuric acid gas, there is indirect in the sulfuric acid gas concentration by obtaining the SO ₃ concentration It can be measured continuously.
[0057]
That is, the suction pipes 3a to 3c are provided with a preheating part 23 for preheating the exhaust gas and a temperature controller 24 for adjusting the temperature of the preheating part 23 to 400 ° C. or more and 450 ° C. or less, thereby providing sulfuric acid in the exhaust gas. The sulfuric acid gas concentration can be measured by changing the gas to SO ₃ .
[0058]
Moreover, this sulfuric acid gas concentration meter may change the magnitude | size of the preheating part 23 according to the decomposition | disassembly rate of a sulfuric acid gas. This sulfuric acid gas concentration meter is required to obtain a concentration obtained by adding both of them under the condition where sulfuric acid gas and SO ₃ are mixed.
[0059]
FIG. 8 is a conceptual diagram of an exhaust gas sampling apparatus showing a modification of the filter used in the SO ₃ concentration meter of the present invention. FIG. 9 is a view showing a state where the exhaust gas sampling device shown in FIG. 8 is attached to the flue of the combustion facility.
[0060]
The filter 5 shown in FIGS. 1, 5 and 7 is a container filled with glass wool, whereas the exhaust gas sampling device 26 samples only the exhaust gas from the exhaust gas discharged from the combustion facility or the like and containing dust. An exhaust gas sampling device, wherein a suction port 27a is connected to the upstream side of the flue 1 of the combustion facility and a discharge port 27b is connected to the downstream side of the flue 1, and the inner wall is inserted in the middle of the duct 27 The duct 27 includes a substantially cylindrical filter 28 having substantially the same cross-sectional shape, and a cover 29 that covers the outside of the filter 28 and has a take-out port 29a for taking out the filtered exhaust gas.
[0061]
The duct 27 is inserted with a pump 30 for sucking exhaust gas containing dust from the flue 1 and forcibly discharging it into the flue 1.
[0062]
When this sampling apparatus is used in the SO ₃ concentration meter shown in FIG. 1, the suction port and the discharge port of the duct 27 are attached to the flue 1 after removing the suction pipe 3a and the filter 5 of the SO ₃ concentration meter. The extraction port 29a may be attached to the suction pipe 3b (in this case, two pumps 7 and 30 are used).
[0063]
According to this exhaust gas sampling device, since the filter 28 has a substantially cylindrical shape having substantially the same cross-sectional shape as the duct 27, there is little resistance to block the flow when dust-containing exhaust gas flows in the direction of the arrow 31 in the filter 28. Even if the dust 32 adheres to and accumulates on the inner wall of the filter 28, it is pushed by the flow of exhaust gas, so that it passes through the duct 27 again and returns to the flue 1 so that the filter 28 is hardly clogged. The SO ₃ gas in the exhaust gas sucked into the duct 27 passes through the filter 28 in the direction of the arrow 33 and is sent to the cavity 6 in the direction of the arrow 34 from the take-out port 29a formed in the cover 29.
[0064]
In addition, since a pump 30 for inserting exhaust gas into the duct 27 and forcibly discharging it into the flue 1 is inserted, the flow rate of exhaust gas flowing in the direction of arrows 35 and 36 in the duct 27 is increased. The dust 32 adhering to the filter 28 without being reduced is forcibly removed and discharged to the flue 1 so that the filter 28 is hardly clogged.
[0065]
【The invention's effect】
In short, according to the present invention, the following excellent effects are exhibited.
[0066]
It is possible to provide an SO ₃ concentration meter that can continuously measure the concentration of SO _{3 in} the 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 is a graph showing an absorption spectrum of SO ₃ measured using the SO ₃ concentration meter shown in FIG.
FIG. 3 is a diagram showing the results of measuring SO ₂ spectrum and 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 SO ₃ composition, water concentration, and 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 a filter used in the SO ₃ concentration meter of the present invention.
9 is a view 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 Photodetection element 13 Arithmetic unit

Claims (4)

An SO ₃ concentration meter for measuring the concentration of SO ₃ in exhaust gas containing SO ₂ and SO _{3 in} a flue of a combustion facility or the like, comprising an intake pipe for sucking exhaust gas from the flue and exhaust gas in the flue A cavity having two transparent windows facing each other, a heater for heating so as to keep the temperature of the exhaust gas sucked into the cavity at 350 ° C. to 450 ° C., and the above A light source for irradiating light into the cavity, a reflection mirror disposed outside the cavity and reciprocating the light from the light source into the cavity a plurality of times, and a wavelength of 200 nm to 260 nm among the light after reciprocation SO ₃ concentration meter, characterized in that a calculating means for calculating the SO ₃ concentration in the flue gas by that spectroscopic analysis light. 2. The SO according to claim 1, further comprising a preheating portion that is provided between the cavity and the suction pipe and preheats exhaust gas passing through the suction pipe. _Three Densitometer. The SO ₃ concentration meter according to claim 1 or 2 , wherein a filter for removing dust in the exhaust gas is provided in the intake pipe. The SO ₃ concentration meter according to any one of claims 1 to 3, further comprising a pump for forcibly discharging the exhaust gas in the cavity to the flue in the middle of the discharge pipe.

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