CN110687062A - Detection system and detection method for sulfur trioxide content in flue gas - Google Patents
Detection system and detection method for sulfur trioxide content in flue gas Download PDFInfo
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- CN110687062A CN110687062A CN201910942860.XA CN201910942860A CN110687062A CN 110687062 A CN110687062 A CN 110687062A CN 201910942860 A CN201910942860 A CN 201910942860A CN 110687062 A CN110687062 A CN 110687062A
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- AKEJUJNQAAGONA-UHFFFAOYSA-N sulfur trioxide Chemical compound O=S(=O)=O AKEJUJNQAAGONA-UHFFFAOYSA-N 0.000 title claims abstract description 155
- 239000003546 flue gas Substances 0.000 title claims abstract description 132
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 129
- 238000001514 detection method Methods 0.000 title claims abstract description 24
- 238000004448 titration Methods 0.000 claims abstract description 259
- 239000007788 liquid Substances 0.000 claims abstract description 132
- 238000002835 absorbance Methods 0.000 claims abstract description 78
- 238000000034 method Methods 0.000 claims abstract description 63
- 239000000126 substance Substances 0.000 claims abstract description 17
- 239000000243 solution Substances 0.000 claims description 184
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 77
- 238000002360 preparation method Methods 0.000 claims description 60
- 229910001422 barium ion Inorganic materials 0.000 claims description 29
- 238000000605 extraction Methods 0.000 claims description 25
- 239000012086 standard solution Substances 0.000 claims description 25
- XDFCIPNJCBUZJN-UHFFFAOYSA-N barium(2+) Chemical compound [Ba+2] XDFCIPNJCBUZJN-UHFFFAOYSA-N 0.000 claims description 23
- 238000012545 processing Methods 0.000 claims description 20
- 238000005070 sampling Methods 0.000 claims description 20
- 230000008569 process Effects 0.000 claims description 16
- 239000000779 smoke Substances 0.000 claims description 15
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 14
- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 claims description 11
- 229910052776 Thorium Inorganic materials 0.000 claims description 11
- 239000003153 chemical reaction reagent Substances 0.000 claims description 9
- 238000001914 filtration Methods 0.000 claims description 8
- 239000007864 aqueous solution Substances 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims description 4
- 238000010521 absorption reaction Methods 0.000 abstract description 20
- -1 sulfur trioxide compound Chemical class 0.000 abstract description 4
- 238000012360 testing method Methods 0.000 description 23
- 150000002500 ions Chemical class 0.000 description 6
- 238000005259 measurement Methods 0.000 description 4
- 239000000523 sample Substances 0.000 description 4
- 229910001626 barium chloride Inorganic materials 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- XJEUTYCBQNHUTC-UHFFFAOYSA-N [Th].[Ba] Chemical compound [Th].[Ba] XJEUTYCBQNHUTC-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000003344 environmental pollutant Substances 0.000 description 2
- 239000003517 fume Substances 0.000 description 2
- 238000012067 mathematical method Methods 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- 230000000007 visual effect Effects 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- WDIHJSXYQDMJHN-UHFFFAOYSA-L barium chloride Chemical compound [Cl-].[Cl-].[Ba+2] WDIHJSXYQDMJHN-UHFFFAOYSA-L 0.000 description 1
- OOULUYZFLXDWDQ-UHFFFAOYSA-L barium perchlorate Chemical compound [Ba+2].[O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O OOULUYZFLXDWDQ-UHFFFAOYSA-L 0.000 description 1
- 159000000009 barium salts Chemical class 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 239000005457 ice water Substances 0.000 description 1
- 238000004255 ion exchange chromatography Methods 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000013618 particulate matter Substances 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000012088 reference solution Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000012488 sample solution Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/33—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using ultraviolet light
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/16—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using titration
- G01N31/162—Determining the equivalent point by means of a discontinuity
Abstract
The invention provides a detection system and a detection method for sulfur trioxide content in flue gas, and belongs to the technical field of sulfur trioxide detection. The method utilizes the time point at which the second derivative of the product function of the absorbance and the titration liquid is zero as the determination end point, can effectively avoid the interference of complex components in the flue gas on the absorbance, and avoids the larger deviation caused by the fact that the sulfur trioxide concentration is determined by relying on the absorbance or the linear relation between the conductivity and the characteristic absorption peak of the sulfur trioxide compound due to the complex chemical components of the flue gas.
Description
Technical Field
The invention relates to the technical field of sulfur trioxide detection, and particularly provides an online detection system and method for sulfur trioxide content in flue gas.
Background
Along with the comprehensive implementation of 'ultra-low emission' transformation of coal-fired power plants in China and the implementation of GB13223-2011 'emission standard of atmospheric pollutants for thermal power plants', increasingly important attention is paid to the detection and control of pollutants in flue gas of thermal power plants. SO in flue gas of thermal power plant3Can obviously improve the dew point temperature of acid in the flue gas and aggravate the corrosion of a low-temperature area. In addition, SO3With water in the flue gasThe steam is condensed into sulfuric acid mist, and can also form viscous NH with escaped ammonia4SO4And the damage to the air preheater and the tail flue is large. Therefore, SO in the flue gas can be rapidly and accurately measured3The content of the (D) has great significance for equipment monitoring and safe operation of a coal-fired power plant.
SO in the present flue gas3The detection method mainly comprises the step of detecting SO in the flue gas3After absorbing or condensing to form a solution, measuring the concentration of sulfate ions in the solution, wherein the following types are specific: the first is a manual titration method, using thorium reagent as indicator, and titration is performed with isopropanol solution of barium salt. This method is the standard method specified in EPA method8 and method 8A. The method has the disadvantages that the titration process consumes energy, the color change of the titration endpoint is difficult to judge manually, and errors are easy to generate. The second is a spectrophotometer method, which utilizes the linear relation between the absorbance and the thorium-barium complex concentration to measure the SO in the solution4 2-The ion concentration. The method has good effect under laboratory conditions, but in practical application, the smoke components are extremely complex, so that the influence on the absorbance is very large, and the practical test result is very unsatisfactory. There are other methods such as ion chromatography, which are not suitable for on-site testing due to the complicated equipment and instruments and are less practical.
From the results of the current literature research, the domestic coal-fired power plant flue gas SO3The detection of (2) has no unified standard and method, and the problem of low accuracy of the test result generally exists in the prior art, so that the increasing detection requirements cannot be met. For example, patent No. 200910211691.9 discloses a method and apparatus for detecting, measuring and controlling sulfur trioxide and other condensables in flue gas, which technique is based on the principle of using a dynamic temperature change probe to detect temperature and current changes and using conductivity to calculate SO3The concentration of (c). Patent No. 201310376879.5 discloses an on-line detection device and method for sulfur trioxide in flue gas, and the technical principle thereof lies in that a spectrophotometer is used for measuring the concentration of sulfur trioxide in flue gas. Patent No. 201410340268.X discloses a method and system for determining sulfur dioxide and sulfur trioxide in flue gas, but not explicitly usingMethod for testing SO in solution4 2-The ion concentration.
Disclosure of Invention
Aiming at the problems in the prior art, the embodiment of the invention provides a system and a method for detecting the content of sulfur trioxide in flue gas, wherein the method utilizes a time point at which the second derivative of a product function of absorbance and titration liquid is zero as a determination end point, so that the interference of complex components in the flue gas on the absorbance can be effectively avoided, and the larger deviation caused when the concentration of the sulfur trioxide is determined by relying on the absorbance or the linear relation between the conductivity and the characteristic absorption peak of the sulfur trioxide compound due to the complex chemical components of the flue gas is avoided.
The technical solution of the invention is as follows:
a method for detecting the content of sulfur trioxide in flue gas comprises the following steps:
absorbing a preset volume of flue gas by using a certain volume of isopropanol solution to obtain a liquid to be detected;
using a known concentration of Ba2+Titrating a certain volume of liquid to be measured by using the titration solution, and measuring the absorbance of a titration system at different titration time points by using a photometric electrode with a preset wavelength, wherein the titration system contains a titration indicator;
taking a time point at which the second derivative of a fitting function of the absorbance and the volume of the used titration liquid is zero in the titration process as a titration end point, and determining the dosage of the titration liquid;
and determining the concentration of sulfur trioxide in the flue gas according to the dosage of the titration solution.
In an alternative embodiment, the method for determining the fitting function of the absorbance and the volume of the titration liquid comprises:
recording the absorbance and the volume of the titration solution at each titration time point by taking the absorbance as a vertical coordinate and the volume of the used titration solution as a horizontal coordinate;
according to the least squares method, a fit function of absorbance to volume of used titration liquid is determined.
In an optional embodiment, the determining the concentration of sulfur trioxide in the flue gas according to the dosage of the titration liquid includes:
determining the concentration A of sulfur trioxide in the flue gas according to the following formula:
wherein, VTBa used for reaching titration end point2+Volume of the titration solution, C is Ba2+Ba in the titration solution2+And (3) concentration, wherein L is the total volume of the solution to be detected, L1 is the volume of the solution to be detected for titration, and Q is the volume of the smoke.
In an optional embodiment, the preset volume is 200-3000L, and the smoke collection rate is 0.1-10L/min.
In an optional embodiment, the titration system comprises 40-60 ml of solution to be detected and 2-3 drops of thorium reagent aqueous solution with the concentration of 1-3 mg/ml; said Ba2+The concentration of the titration solution is 0.125-12.5 mmol/L.
In an optional embodiment, the titration is performed while stirring the titration system at a rotation speed of 300-600 r/min, and the Ba is added during each titration2+The dosage of the titration solution is 0.04-0.06 ml.
In an alternative embodiment, the photometric electrode of the preset wavelength is determined according to the following steps:
a series of Ba with different concentrations are prepared2+Standard solution of said Ba2+A certain amount of titration indicator is added into the standard solution;
measuring the series of different concentrations of Ba using an ultraviolet spectrophotometer2+Absorbance of the standard solution under ultraviolet light with different wavelengths;
according to Ba2+Determining the optimal wavelength by the linear correlation of the concentration of the standard solution and the absorbance;
if the photometric electrode with the optimal wavelength exists, taking the photometric electrode with the optimal wavelength as the photometric electrode with the preset wavelength;
if the photometric electrode with the optimal wavelength does not exist, selecting the photometric electrode with two wavelengths closest to the optimal wavelength as an alternative photometric electrode;
the Ba was doped with a known concentration of sulfate standard2+Titrating the standard solution, respectively measuring the absorbance of the titration system at different titration time points through two alternative photometric electrodes, determining the dosage of a sulfate standard substance by taking the time point at which the second derivative of a fitting function of the absorbance and the volume of the used sulfate standard substance is zero in the titration process as a titration end point, and determining Ba according to the dosage of the sulfate standard substance2+Measured concentration of standard solution;
selecting the measured concentration and the corresponding Ba2+And the candidate photometric electrode with the closest actual concentration of the standard solution is used as the photometric electrode with the preset wavelength.
The utility model provides a sulfur trioxide content's detecting system in flue gas, includes that flue gas extraction unit, solution prepare unit, titration unit and data processing module, flue gas extraction unit is used for extracting the flue gas of predetermineeing the volume, solution prepare the unit be used for with the flue gas of flue gas extraction unit extraction is dissolved in the isopropyl alcohol solution of certain volume and is obtained the liquid of awaiting measuring, titration unit is used for adopting the Ba of known concentration2+The titration solution titrates a certain volume of solution to be measured, the absorbance of a titration system at different titration time points is measured, a titration indicator is contained in the titration system, the data processing module is used for determining the dosage of the titration solution by taking the time point at which the second derivative of a fitting function of the absorbance and the volume of the used titration solution is zero in the titration process as a titration end point, and determining the concentration of sulfur trioxide in the flue gas according to the dosage of the titration solution.
In an optional embodiment, the system for detecting the content of sulfur trioxide in flue gas further comprises a control unit, wherein the control unit is used for controlling the flue gas extraction unit to convey a preset volume of flue gas into the solution preparation unit according to a detection instruction, then controlling the solution preparation unit to absorb the preset volume of flue gas with a certain volume of isopropanol solution to obtain a solution to be detected, then controlling the solution preparation unit to convey a certain volume of solution to be detected to the titration unit, and then controlling the titration unit to adopt Ba with a known concentration2+The solution titrates the liquid to be measured with a certain volume, and the data processing module is processed in the titration processAnd sending the absorbance of the titration system and the titration liquid volume information.
In an optional embodiment, the flue gas extraction unit includes sampling gun, filtering material, intake pipe and air intake pump, filtering material is located the sampling gun input for filter out the particulate matter in the flue gas, in the input of sampling gun stretched into the flue, the output passed through the intake pipe with the solution is prepared the unit and is connected, the air intake pump sets up in the intake pipe, be used for the ration extraction flue gas in the flue.
In an optional embodiment, the solution preparation unit includes a solution preparation container, a liquid inlet pipe, a first liquid metering pump, a liquid outlet pipe, a second liquid metering pump, and an isopropanol solution storage tank, the solution preparation container is provided with a volume identifier and stores a certain amount of isopropanol solution therein for absorbing the preset volume of the fume conveyed by the fume extraction unit, one end of the liquid inlet pipe is connected to the solution preparation container, the other end of the liquid inlet pipe is connected to the isopropanol solution storage tank, the first liquid metering pump is disposed on the liquid inlet pipe and is used for conveying the isopropanol solution into the solution preparation container when the solution preparation container is opened so that the liquid level in the solution preparation container reaches the volume identifier, one end of the liquid outlet pipe is connected to the solution preparation container, the other end of the liquid outlet pipe is connected to the titration unit, the second liquid metering pump is disposed on the liquid outlet pipe, and the titration unit is used for quantitatively conveying the liquid to be detected to the titration unit when the titration unit is started.
In an optional embodiment, the solution preparation device comprises a control unit, the solution preparation unit further comprises a liquid level indicator, the liquid level indicator is used for sending a signal to the control unit when the liquid level in the solution preparation container reaches the volume identifier, the control unit is used for controlling the first liquid metering pump to be started after the smoke extraction unit sends a preset volume of smoke into the solution preparation unit, the isopropanol solution is sent into the solution preparation container, and the first liquid metering pump is closed when the signal sent by the liquid level indicator is received, so that the purpose that the smoke with the preset volume is absorbed by the isopropanol solution with a certain volume to obtain the liquid to be detected is achieved.
In an alternative embodiment, the titration unit comprises a titration vessel, a burette, Ba2+A titration liquid storage tank, a third liquid metering pump and a photometric electrode, wherein a titration indicator is stored in the titration container, the titration container is used for receiving the liquid to be tested with a certain volume conveyed by the solution preparation unit, and one end of the titration tube and the Ba are arranged2+The titration liquid storage tank is connected, the other end of the titration liquid storage tank is connected with the titration container, the third liquid metering pump is arranged on the titration tube and is used for dropping Ba into the titration container at a constant speed when the titration tube is opened2+And the photometric electrode measuring end is inserted below the liquid level of the titration container, and the output end of the titration container is used for sending absorbance data of different titration time points to the data processing module.
In an alternative embodiment, the titration unit further comprises an agitator, the agitator being located within the titration vessel.
In an optional embodiment, the system for detecting the content of sulfur trioxide in flue gas comprises a control unit, wherein after the data processing module judges a titration end point, a titration end signal is sent to the control unit, and the control unit controls the third liquid metering pump to be closed according to the titration end signal.
Compared with the prior art, the invention has the beneficial effects that:
the method for detecting the content of sulfur trioxide in the flue gas provided by the embodiment of the invention has the following beneficial effects:
(1) the anti-interference capability is strong:
according to the method for detecting the content of sulfur trioxide in the flue gas, the absorbance of the titration solution is measured by adopting the photometric electrode while titration is carried out, and the time point at which the second derivative of the product function of the absorbance and the titration solution is zero is used as the determination end point, so that the interference of complex components in the flue gas on the absorbance can be effectively avoided, and the large deviation caused when the concentration of sulfur trioxide is determined by relying on the linear relation between the absorbance or the conductivity and the characteristic absorption peak of sulfur trioxide compound due to the complex chemical components of the flue gas is avoided;
(2) the accuracy is high:
according to the method for detecting the content of sulfur trioxide in the flue gas, the photometric electrode and a mathematical method are combined, so that the titration end point can be accurately judged, the result has high accuracy, and subjective errors caused by visual observation are avoided;
(3) the cost is low:
compared with large-scale test instruments such as a spectrophotometer and an ion chromatograph, the invention has obvious advantage in equipment cost;
(4) the method is simple and easy for field operation:
compared with most of sulfur trioxide testing instruments on the market, the instrument and the method can be used for testing on site, the measurement result can be obtained in real time, and online testing can be realized.
Drawings
FIG. 1 is a schematic diagram of a system for detecting sulfur trioxide content in flue gas according to an embodiment of the present invention;
FIG. 2 is a flowchart of a method for detecting sulfur trioxide content in flue gas according to an embodiment of the present invention;
FIG. 3a is a graph showing the absorbance as a function of the volume of the used titration solution provided by an embodiment of the present invention;
FIG. 3b is a schematic diagram of the second derivative of the fitting function according to an embodiment of the present invention;
FIG. 4 shows Ba of different concentrations provided in example 1 of the present invention2+Ultraviolet scanning curve of standard solution sample;
FIG. 5 shows Ba contents varied according to embodiment 1 of the present invention2+Ion absorbance standard curve chart.
Detailed Description
The following detailed description of embodiments of the invention will be made with reference to the accompanying drawings.
As shown in fig. 2, an embodiment of the present invention provides a method for detecting sulfur trioxide content in flue gas, including the following steps:
step a: quantitatively extracting smoke with a preset volume;
step b: absorbing the preset volume of the smoke gas by using a certain volume of isopropanol solution to obtain a liquid to be detected;
specifically, the isopropanol solution is preferably an isopropanol aqueous solution with the mass concentration of 75-85%, and more preferably an isopropanol aqueous solution with the mass concentration of 80%;
step c: using a known concentration of Ba2+Titrating a certain volume of liquid to be measured by using the titration solution, and measuring the absorbance of a titration system at different titration time points by using a photometric electrode with a preset wavelength, wherein the titration system contains a titration indicator;
specifically, the titration indicator is preferably 1- (2-phenylarsonic acid phenylazo) -2-naphthol-3, 6-disulfonic acid disodium salt (thorium reagent); ba2+The titration solution can be barium ion solution such as barium chloride, barium perchlorate and the like; the absorbance of each titration time point can be measured and recorded in real time through a photometric electrode, and the dosage of the titration solution at each titration time point is determined according to the flow rate of the titration solution and the titration time;
step d: taking a time point at which the second derivative of a fitting function of the absorbance and the volume of the used titration liquid is zero in the titration process as a titration end point, and determining the dosage of the titration liquid;
specifically, a coordinate system can be established by taking the absorbance and the volume of the used titration solution as horizontal and vertical coordinates respectively, the absorbance at each moment and the corresponding volume of the current used titration solution are recorded during titration, and fitting is performed according to points in the coordinate system to obtain a fitting function of the absorbance and the volume of the used titration solution;
step e: and determining the concentration of sulfur trioxide in the flue gas according to the dosage of the titration solution.
In an optional embodiment, the preset volume is 200-3000L, the flue gas collection rate is 0.1-10L/min, when the flue gas collection amount is the volume and the rate, the effective detection of sulfur trioxide can be ensured, and the problem that the measured concentration is lower than an actual value due to the fact that sulfur trioxide cannot be effectively absorbed in the absorption process due to the fact that the flue gas amount is too large and the flow speed is relatively quick can be solved.
In an optional embodiment, the titration system comprises 40-60 ml of solution to be tested and 2-3 drops of thorium test with the concentration of 1-3 mg/mlAn aqueous agent solution; said Ba2+The concentration of the titration solution is 0.125-12.5 mmol/L. Under the titration system, good titration effect can be ensured, and good economical efficiency is achieved.
In an optional embodiment, the titration is performed while stirring the titration system at a rotation speed of 300-600 r/min, and the Ba is added during each titration2+The dosage of the titration solution is 0.04-0.06 ml. By controlling the dosage of the titration solution of the tachometer, the titrating agent which is dripped each time can reach the potential difference dE of 0.5mv, and the titration end point can be conveniently controlled.
In an alternative embodiment, the photometric electrode of the preset wavelength is determined according to the following steps:
a series of Ba with different concentrations are prepared2+Standard solution of said Ba2+A certain amount of titration indicator is added into the standard solution;
measuring the series of different concentrations of Ba using an ultraviolet spectrophotometer2+Absorbance of the standard solution under ultraviolet light with different wavelengths;
according to Ba2+Determining the optimal wavelength by the linear correlation of the concentration of the standard solution and the absorbance;
if the photometric electrode with the optimal wavelength exists, taking the photometric electrode with the optimal wavelength as the photometric electrode with the preset wavelength;
if the photometric electrode with the optimal wavelength does not exist, selecting the photometric electrode with two wavelengths closest to the optimal wavelength as an alternative photometric electrode;
the Ba was doped with a known concentration of sulfate standard2+Titrating the standard solution, respectively measuring the absorbance of the titration system at different titration time points through two alternative photometric electrodes, determining the dosage of a sulfate standard substance by taking the time point at which the second derivative of a fitting function of the absorbance and the volume of the used sulfate standard substance is zero in the titration process as a titration end point, and determining Ba according to the dosage of the sulfate standard substance2+Measured concentration of standard solution;
selecting the measured concentration and the corresponding Ba2+Alternative light with the closest actual concentration of standard solutionThe photometric electrode is used as a photometric electrode with a preset wavelength.
By determining the photometric electrode with the proper wavelength by the method, the interference of complex components in the smoke on the test result can be avoided; but also can ensure the sensitivity of the absorbance to the color reaction and improve the accuracy of the test result.
In an optional embodiment, when the concentration of sulfur trioxide in the flue gas is 0.5-20 mg/m3The absorbance of the titration system at different titration time points is measured by using a photometric electrode with the wavelength of 520nm or 555nm, and the absorbance is preferably measured by using a photometric electrode with the wavelength of 520 nm.
The method for detecting the content of sulfur trioxide in the flue gas provided by the embodiment of the invention has the following beneficial effects:
(1) the anti-interference capability is strong: according to the method for detecting the content of sulfur trioxide in the flue gas, the absorbance of the titration solution is measured by adopting the photometric electrode while titration is carried out, and the time point at which the second derivative of the product function of the absorbance and the titration solution is zero is used as the determination end point, so that the interference of complex components in the flue gas on the absorbance can be effectively avoided, and the large deviation caused when the concentration of sulfur trioxide is determined by relying on the linear relation between the absorbance or the conductivity and the characteristic absorption peak of sulfur trioxide compound due to the complex chemical components of the flue gas is avoided;
(2) the accuracy is high:
according to the method for detecting the content of sulfur trioxide in the flue gas, the photometric electrode and a mathematical method are combined, so that the titration end point can be accurately judged, the result has high accuracy, and subjective errors caused by visual observation are avoided;
(3) the cost is low:
compared with large-scale test instruments such as a spectrophotometer and an ion chromatograph, the invention has obvious advantage in equipment cost;
(4) the method is simple and easy for field operation:
compared with most of sulfur trioxide testing instruments on the market, the instrument and the method can be used for testing on site, the measurement result can be obtained in real time, and online testing can be realized.
Specifically, the method for determining the fitting function of the absorbance and the volume of the titration liquid comprises the following steps:
recording the absorbance and the volume of the titration solution at each titration time point by taking the absorbance as a vertical coordinate and the volume of the titration solution as a horizontal coordinate;
and determining a fitting function of the absorbance and the volume of the titration solution according to the principle of a least square method.
The method can test and obtain the real level of the sulfur trioxide content in the flue gas to the maximum extent by means of online real-time sampling and analysis, avoids the possible change of absorbance in the sample transfer process, simultaneously can also avoid the interference of complex components in the flue gas on the characteristic absorption peak of the thorium-barium complex, destroys the linear relation between the characteristic absorption peak and barium ions and sulfate ions, further titrates the absorption liquid, fits the absorbance and the volume of the titration liquid by a least square method, performs second derivation on a fitting function, determines the point with the second derivative being zero as a titration end point, and ensures the accurate determination of the titration end point.
Specifically, the determining the concentration of sulfur trioxide in the flue gas according to the dosage of the titration solution comprises:
determining the concentration A of sulfur trioxide in the flue gas according to the following formula:
wherein, VTBa used for reaching titration end point2+Volume of the titration solution, C is Ba2+Ba in the titration solution2+And (3) concentration, wherein L is the total volume of the solution to be detected, L1 is the volume of the solution to be detected for titration, and Q is the volume of the smoke.
Specifically, in the examples of the present invention, Ba was used up to the end point of titration2+Volume V of the titration solutionTCan be determined directly by a metering pump or according to the titration rate and titration time; titration Rate, Ba2+The parameters of concentration, total volume of the liquid to be measured, volume of the liquid to be measured for titration, smoke volume and the like can be preset in the data processing module, and can also be correspondingly sensed according to requirementsThe device transmits the data to the data processing module in real time.
As shown in fig. 1, an embodiment of the present invention further provides a system for detecting a content of sulfur trioxide in flue gas, including a flue gas extraction unit 10, a solution preparation unit 20, a titration unit 30 and a data processing module 40, where the flue gas extraction unit 10 is configured to extract flue gas with a preset volume, the solution preparation unit 20 is configured to dissolve the flue gas extracted by the flue gas extraction unit 10 in an isopropanol solution with a certain volume to obtain a solution to be detected, and the titration unit 30 is configured to use Ba with a known concentration2+Titration liquid titrates the liquid to be measured of a certain volume to measure the absorbance of a titration system at different titration time points, the titration system contains a titration indicator, the data processing module 40 is used for determining the dosage of the titration liquid by taking the time point at which the second derivative of the fitting function of the absorbance and the used titration liquid volume is zero in the titration process as a titration end point, and determining the concentration of sulfur trioxide in the flue gas according to the dosage of the titration liquid.
Further, detecting system of sulfur trioxide content in flue gas still include the control unit, the control unit is used for according to the detection instruction, control earlier flue gas extraction unit 10 carries the flue gas of predetermineeing the volume in to solution preparation unit 20, then control solution preparation unit 20 adopts the isopropyl alcohol solution of certain volume to absorb the flue gas of predetermineeing the volume obtains waiting to detect the liquid, later control solution preparation unit 20 to titration unit 30 carries the liquid that awaits measuring of certain volume, control later titration unit 30 adopts Ba2+ solution of known concentration to titrate the liquid that awaits measuring of certain volume to in titration process to data processing module 40 sends the absorbance of titration system and titrates liquid volume information.
Specifically, in the embodiment of the present invention, the detection instruction may be a detection instruction sent by a user, or may be a detection instruction preset according to needs, which is not limited in the present invention; the control unit can realize the on-off control of each unit part by controlling the opening and closing of the electric control valves of other units;
by arranging the control unit, real-time online detection is realized, labor force is saved, and detection efficiency is improved.
Specifically, in an optional embodiment, as shown in fig. 1, the flue gas extraction unit 10 includes a sampling gun 11, a filtering material, an air inlet pipe 12 and an air inlet pump 13, where the filtering material is located at an input end of the sampling gun 11 and is used for filtering out particulate matters in the flue gas, the input end of the sampling gun 11 is inserted into a flue, an output end of the sampling gun is connected to the solution preparation unit 20 through the air inlet pipe, and the air inlet pump 13 is disposed on the air inlet pipe 12 and is used for quantitatively extracting the flue gas in the flue.
Specifically, in the embodiment of the invention, the heat tracing temperature of the sampling gun 11 during sampling is preferably 100-200 ℃;
in an alternative embodiment, as shown in fig. 1, the solution preparation unit 20 includes a solution preparation container 21, a liquid inlet pipe 22, a first liquid metering pump 23, a liquid outlet pipe 24, a second liquid metering pump 25, and an isopropanol solution storage tank 26, a volume mark a is disposed on the solution preparation container 21, a certain amount of isopropanol solution is stored in the solution preparation container 21 for absorbing the preset volume of the flue gas delivered by the flue gas extraction unit 10, one end of the liquid inlet pipe 22 is connected to the solution preparation container 21, the other end of the liquid inlet pipe 22 is connected to the isopropanol solution storage tank 26, the first liquid metering pump 23 is disposed on the liquid inlet pipe 22 for delivering the isopropanol solution into the solution preparation container 21 when the solution preparation container is opened so that the liquid level in the solution preparation container 21 reaches the volume mark a, one end of the liquid outlet pipe 24 is connected to the solution preparation container 21, the other end is connected with the titration unit 30, and the second liquid metering pump 25 is arranged on the liquid outlet pipe 24 and used for quantitatively conveying the liquid to be detected to the titration unit 30 when the titration unit is started.
Specifically, in the embodiment of the present invention, the solution preparation container 21 is preferably placed in an environment at 110 to 10 ℃;
further, detecting system of sulfur trioxide content in flue gas, including the control unit, solution preparation unit 20 still includes liquid level indicator, liquid level indicator is used for liquid level in the solution preparation container reaches during the volume sign to the control unit sends a signal, the control unit is used for flue gas extraction unit 10 to carry the control behind the flue gas of predetermineeing the volume in the solution preparation unit 20 first liquid metering pump is opened, to carry the isopropyl alcohol solution in the solution preparation container, close when receiving the signal that liquid level indicator sent first liquid metering pump realizes adopting the isopropyl alcohol solution absorption of certain volume the flue gas of predetermineeing the volume obtains waiting to detect the liquid.
In an alternative embodiment, as shown in fig. 1, the titration unit 30 comprises a titration container 31, a burette 32, Ba2+A titration liquid storage tank 33, a third liquid metering pump 34 and a photometric electrode 35, wherein a titration indicator is stored in the titration container 31, the titration container 31 is used for receiving the liquid to be measured with a certain volume delivered by the solution preparation unit 20, and one end of the titration tube 32 and the Ba are connected2+A titration liquid storage tank 33 is connected, the other end is connected with the titration container 31, and a third liquid metering pump 34 is arranged on the titration tube 32 and is used for dropping Ba into the titration container 31 at a constant speed when the titration tube is opened2+The measuring end of the photometric electrode 35 is inserted under the liquid level of the titration container 31, and the output end of the titration liquid is used for sending absorbance data of different titration time points to the data processing module 40.
Further, detecting system of sulfur trioxide content in flue gas include the control unit, data processing module 40 judges after titrating the terminal point, to the control unit sends and titrates the end signal, the control unit basis titrate end signal control the third liquid measuring pump is closed to avoid titrating the waste of liquid.
The following are specific examples of the present invention and comparative examples:
each of the examples and comparative examples measured simulated flue gas containing sulfur trioxide at an actual emission concentration of 5mg/m3Besides sulfur trioxide, the common NOx and SO in the flue gas are added2、NH3A gas.
Example 1
As shown in fig. 1, the present embodiment provides a system for detecting sulfur trioxide content in flue gas, including: a smoke extraction unit 10, a solution preparation unit 20, a titration unit 30 and a data processing module 40.
Before detecting sulfur trioxide in flue gas, the wavelength of a required photometric electrode is determined in the embodiment, and the specific method comprises the following steps:
1. and (3) color development reaction:
(1) 0,0.1,0.2,0.4,0.6,0.8 and 1.0mL of 0.01mol/L barium ion solution was added to a 25mL colorimetric tube.
(2) 0.2mL of a 2mg/mL aqueous solution of thorium reagent was added and the volume was brought to 25mL with 80% isopropanol.
(3) Mixing the solution uniformly, standing for 15min to obtain a series of Ba with different concentrations2+And (4) standard solution samples.
2. Selecting characteristic wavelength by using a purple spectrophotometer:
(1) baseline was calibrated to remove blank background effects using 80% isopropanol solution as a reference solution.
(2) The developed sample solution was added to a 10mm quartz cuvette and placed in a sample cell.
(3) The scanning curve was obtained by uv spectrophotometer. The scanning curve is shown in fig. 4. As can be seen from FIG. 4, in the wavelength range of 500-600 nm, a good linear relationship exists between the thorium reagent-barium ion ultraviolet absorbance and barium ion concentration.
(4) The absorbance of barium ions with different concentrations under ultraviolet light with different wavelengths is selected to make a first-order curve, and the wavelength with the best linearity is selected as the characteristic wavelength (namely the preset wavelength). As shown in FIG. 5, it was found by comparison that Ba was present at a wavelength of 535nm2+Since the correlation coefficient between the amount of addition and the absorbance was 0.999 or more, 535nm wavelength was selected as the characteristic absorption wavelength.
3. And selecting the wavelength of the photometric electrode. And (3) selecting photometric electrodes with similar wavelengths according to the characteristic absorption wavelengths determined in the step (2), and performing accuracy verification test by using a standard substance to finally determine the wavelengths used by the photometric electrodes. The specific method comprises the following steps:
(1) photometric electrodes of two wavelengths (520nm and 555nm) closest to 530nm were selected for testing. Firstly, the reference value of the photometric electrode is corrected by using water as a background, and the electrode potential is adjusted to 1000 mv.
(2) 50mL of sulfate radical standard substance with known concentration of 2mg/L is taken and dropped into 2-3 drops of 2mg/mL thorium reagent water solution. Titration was carried out using a photometric electrode with a wavelength of 520nm, the error between the measurement and the concentration of the standard substance being 1.25%; the error between the measurement result and the standard substance concentration was 1.68% when the titration was performed using a photometric electrode using a wavelength of 555 nm. Comparing the two, selecting the photometric electrode with the wavelength of 520nm with smaller test error for testing. When sulfur trioxide in the flue gas is detected, the heat tracing temperature of the sampling gun is 150 ℃, and the front end of the sampling gun is provided with a filtering material for filtering particulate matters in the flue gas. The absorption liquid in the absorption bottle (solution preparation container) is an isopropanol aqueous solution with the mass concentration of 80%, and the absorption bottle is placed in an ice-water bath. Under the suction action of the air inlet pump, the flue gas enters the absorption liquid through the sampling gun, and SO in the flue gas3Is absorbed by the absorption liquid. Record the total volume Q of the smoke as 1m3Wherein, Q is v x t, v is the gas flow rate at the time of sampling by the sampling gun is 5L/min, t is the sampling time, specifically 200 min.
And in the solution preparation unit 20, the absorption liquid is metered to 250ml to obtain the liquid to be detected.
In the titration control unit 30, 50mL of the solution to be tested is extracted from the solution preparation unit, and 3 drops of 2mg/mL thorium reagent aqueous solution are dropped as an indicator. With 0.0125mol/L of BaCl2Titrating the solution as a titration solution, stirring a titration system at a rotating speed of 400r/min while titrating, wherein the Ba is used for titrating each time2+The titration solution is used in an amount of 0.05ml, in the titration process, absorbance at a wavelength of 520nm is recorded by a photometric electrode, as shown in FIG. 3, the absorbance E is used as a vertical coordinate, the volume V of the used titration solution is used as a vertical coordinate, a function is fitted according to the relationship between the two solutions at different titration time points, as shown in FIG. 3b, the value of the second derivative of the fitted function is obtained, and when the second derivative is recorded as zero, the dropping volume V of the titration solutionT。
In the data processing module, the system passes through the formula
And calculating the concentration A of sulfur trioxide in the flue gas, and converting and outputting the result according to the unit required by the user.
The measured concentration of the sulfur trioxide in the flue gas is 5mg/m3. The concentration measured by adopting an ultraviolet wind-solar photometer is 8mg/m3。
Example 2
The embodiment is basically the same as the embodiment 1, and the only difference is that the online detection system further comprises a control unit, and the control unit controls each unit by controlling the opening and closing of the pumps of other units.
The test result of this example was 4.9mg/m3。
Comparative example
And testing the sulfur trioxide concentration in the flue gas by using an ultraviolet spectrophotometer method.
First step of plotting absorbance versus SO4 2-Concentration standard curve. Respectively adding 0.2ml of thorium reagent into a plurality of 25ml colorimetric tubes, and then respectively adding 1.0ml of SO with each concentration4 2-The solution is added with BaCl in each cuvette20.625ml of standard solution is evenly shaken and then fixed by 80 percent isopropanol. At the ultraviolet characteristic absorption peak of 530nm, SO with different concentrations4 2-The solution is represented by an abscissa, the absorbance at 530nm is represented by an ordinate, the result is subjected to linear fitting, and the result of the linear fitting is that y is 0.0085x +0.9834, wherein x is SO in the prepared standard solution4 2-The ion concentration is in mg/L, and y is the absorbance value of a spectrophotometer.
The second step is the testing process. Extracting 1.5m smoke to be detected3Absorbing with 80% isopropanol solution, diluting the absorption solution to 250ml, taking out 25ml solution, adding 0.2ml thorium reagent, adding BaCl20.625ml of standard solution, measuring the absorbance of the absorption solution at 530nm, substituting the result into the linear fitting formula, and calculating to obtain the concentration of sulfur trioxide in the flue gas of 8mg/m3。
The above description is only one embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
The invention has not been described in detail in part of the common general knowledge of those skilled in the art.
Claims (15)
1. A method for detecting the content of sulfur trioxide in flue gas is characterized by comprising the following steps:
absorbing a preset volume of flue gas by using a certain volume of isopropanol solution to obtain a liquid to be detected;
using a known concentration of Ba2+Titrating a certain volume of liquid to be measured by using the titration solution, and measuring the absorbance of a titration system at different titration time points by using a photometric electrode with a preset wavelength, wherein the titration system contains a titration indicator;
taking a time point at which the second derivative of a fitting function of the absorbance and the volume of the used titration liquid is zero in the titration process as a titration end point, and determining the dosage of the titration liquid;
and determining the concentration of sulfur trioxide in the flue gas according to the dosage of the titration solution.
2. The method for detecting the content of sulfur trioxide in flue gas as claimed in claim 1, wherein the method for determining the fitting function of the absorbance and the volume of the titration liquid comprises the following steps:
recording the absorbance and the volume of the titration solution at each titration time point by taking the absorbance as a vertical coordinate and the volume of the used titration solution as a horizontal coordinate;
according to the least squares method, a fit function of absorbance to volume of used titration liquid is determined.
3. The method for detecting the content of sulfur trioxide in flue gas according to claim 1, wherein the determining the concentration of sulfur trioxide in flue gas according to the dosage of the titration solution comprises:
determining the concentration A of sulfur trioxide in the flue gas according to the following formula:
wherein, VTBa used for reaching titration end point2+Volume of the titration solution, C is Ba2+Ba in the titration solution2+And (3) concentration, wherein L is the total volume of the solution to be detected, L1 is the volume of the solution to be detected for titration, and Q is the volume of the smoke.
4. The method for detecting the content of sulfur trioxide in flue gas as claimed in claim 1, wherein the preset volume is 200-3000L, and the collection rate of flue gas is 0.1-10L/min.
5. The method for detecting the content of sulfur trioxide in flue gas according to claim 4, characterized in that the titration system comprises 40-60 ml of solution to be detected and 2-3 drops of thorium reagent aqueous solution with the concentration of 1-3 mg/ml; said Ba2+The concentration of the titration solution is 0.125-12.5 mmol/L.
6. The method for detecting the content of sulfur trioxide in flue gas as claimed in claim 5, wherein the titration is performed while stirring the titration system at a rotation speed of 300-600 r/min, and the Ba is titrated each time2+The dosage of the titration solution is 0.04-0.06 ml.
7. The method for detecting the content of sulfur trioxide in flue gas according to claim 1, characterized in that the photometric electrode of the preset wavelength is determined according to the following steps:
a series of Ba with different concentrations are prepared2+Standard solution of said Ba2+A certain amount of titration indicator is added into the standard solution;
measuring the series of different concentrations of Ba using an ultraviolet spectrophotometer2+Absorbance of the standard solution under ultraviolet light with different wavelengths;
according to Ba2+Determining the optimal wavelength by the linear correlation of the concentration of the standard solution and the absorbance;
if the photometric electrode with the optimal wavelength exists, taking the photometric electrode with the optimal wavelength as the photometric electrode with the preset wavelength;
if the photometric electrode with the optimal wavelength does not exist, selecting the photometric electrode with two wavelengths closest to the optimal wavelength as an alternative photometric electrode;
the Ba was doped with a known concentration of sulfate standard2+Titrating the standard solution, respectively measuring the absorbance of the titration system at different titration time points through two alternative photometric electrodes, determining the dosage of a sulfate standard substance by taking the time point at which the second derivative of a fitting function of the absorbance and the volume of the used sulfate standard substance is zero in the titration process as a titration end point, and determining Ba according to the dosage of the sulfate standard substance2+Measured concentration of standard solution;
selecting the measured concentration and the corresponding Ba2+And the candidate photometric electrode with the closest actual concentration of the standard solution is used as the photometric electrode with the preset wavelength.
8. The utility model provides a sulfur trioxide content's detecting system in flue gas, its characterized in that, prepares unit, titration unit and data processing module including flue gas extraction unit, solution, flue gas extraction unit is used for extracting the flue gas of predetermineeing the volume, solution preparation unit be used for with the flue gas of flue gas extraction unit extraction is dissolved in the isopropyl alcohol solution of certain volume and is obtained the liquid of awaiting measuring, titration unit is used for adopting the Ba of known concentration2+The titration solution titrates a certain volume of solution to be measured, the absorbance of a titration system at different titration time points is measured, a titration indicator is contained in the titration system, the data processing module is used for determining the dosage of the titration solution by taking the time point at which the second derivative of a fitting function of the absorbance and the volume of the used titration solution is zero in the titration process as a titration end point, and determining the concentration of sulfur trioxide in the flue gas according to the dosage of the titration solution.
9. The system for detecting the content of sulfur trioxide in flue gas of claim 8, further comprising a control unit, wherein the control unit is configured to control the flue gas extraction unit to prepare the solution according to a detection instructionConveying a preset volume of flue gas in a preparation unit, controlling a solution preparation unit to absorb the preset volume of flue gas by using a certain volume of isopropanol solution to obtain a solution to be detected, controlling the solution preparation unit to convey a certain volume of the solution to be detected to a titration unit, and then controlling the titration unit to adopt Ba with a known concentration2+And the solution titrates the liquid to be measured with a certain volume, and sends the absorbance of a titration system and the volumetric information of the titrated liquid to the data processing module in the titration process.
10. The system for detecting the content of sulfur trioxide in flue gas according to claim 8 or 9, characterized in that the flue gas extraction unit comprises a sampling gun, a filter material, an intake pipe and an intake pump, wherein the filter material is located at the input end of the sampling gun and used for filtering out particulate matters in the flue gas, the input end of the sampling gun is inserted into the flue, the output end of the sampling gun is connected with the solution preparation unit through the intake pipe, and the intake pump is arranged on the intake pipe and used for quantitatively extracting the flue gas in the flue.
11. The system for detecting the content of sulfur trioxide in flue gas according to claim 8 or 9, wherein the solution preparation unit comprises a solution preparation container, a liquid inlet pipe, a first liquid metering pump, a liquid outlet pipe, a second liquid metering pump and an isopropanol solution storage tank, the solution preparation container is provided with a volume identifier and stores a certain amount of isopropanol solution therein for absorbing the preset volume of flue gas delivered by the flue gas extraction unit, one end of the liquid inlet pipe is connected to the solution preparation container, the other end of the liquid inlet pipe is connected to the isopropanol solution storage tank, the first liquid metering pump is disposed on the liquid inlet pipe and is used for delivering the isopropanol solution into the solution preparation container when the solution preparation container is opened so that the liquid level in the solution preparation container reaches the volume identifier, and one end of the liquid outlet pipe is connected to the solution preparation container, the other end of the liquid metering pump is connected with the titration unit, and the second liquid metering pump is arranged on the liquid outlet pipe and used for quantitatively conveying the liquid to be detected to the titration unit when the liquid metering pump is started.
12. The system for detecting the content of sulfur trioxide in flue gas according to claim 11, comprising a control unit, wherein the solution preparation unit further comprises a liquid level indicator, the liquid level indicator is configured to send a signal to the control unit when the liquid level in the solution preparation container reaches the volume identifier, the control unit is configured to control the first liquid metering pump to be turned on after the flue gas extraction unit delivers a preset volume of flue gas into the solution preparation unit, deliver an isopropanol solution into the solution preparation container, and turn off the first liquid metering pump when receiving the signal sent by the liquid level indicator, so that a certain volume of isopropanol solution is adopted to absorb the preset volume of flue gas to obtain a liquid to be detected.
13. The system for detecting the content of sulfur trioxide in flue gas of claim 8 or 9, characterized in that the titration unit comprises a titration vessel, a burette, Ba2+A titration liquid storage tank, a third liquid metering pump and a photometric electrode, wherein a titration indicator is stored in the titration container, the titration container is used for receiving the liquid to be tested with a certain volume conveyed by the solution preparation unit, and one end of the titration tube and the Ba are arranged2+The titration liquid storage tank is connected, the other end of the titration liquid storage tank is connected with the titration container, the third liquid metering pump is arranged on the titration tube and is used for dropping Ba into the titration container at a constant speed when the titration tube is opened2+And the photometric electrode measuring end is inserted below the liquid level of the titration container, and the output end of the titration container is used for sending absorbance data of different titration time points to the data processing module.
14. The system for detecting the sulfur trioxide content in a flue gas of claim 13, wherein the titration unit further comprises an agitator, the agitator being located within the titration vessel.
15. The system for detecting the content of sulfur trioxide in flue gas of claim 13, comprising a control unit, wherein after the data processing module determines the titration end point, the data processing module sends a titration end signal to the control unit, and the control unit controls the third liquid metering pump to be closed according to the titration end signal.
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| CN113552285A (en) * | 2021-05-28 | 2021-10-26 | 华电电力科学研究院有限公司 | Online flue gas sulfur trioxide intermittent monitoring equipment and method |
| CN113552283A (en) * | 2021-07-23 | 2021-10-26 | 山东百诺医药股份有限公司 | Method for measuring sulfur trioxide content in sulfur trioxide trimethylamine |
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| CN113552285A (en) * | 2021-05-28 | 2021-10-26 | 华电电力科学研究院有限公司 | Online flue gas sulfur trioxide intermittent monitoring equipment and method |
| CN113552283A (en) * | 2021-07-23 | 2021-10-26 | 山东百诺医药股份有限公司 | Method for measuring sulfur trioxide content in sulfur trioxide trimethylamine |
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