CN114112936A - Near-wall smoke component measuring device and method for boiler water-cooled wall - Google Patents
Near-wall smoke component measuring device and method for boiler water-cooled wall Download PDFInfo
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- CN114112936A CN114112936A CN202111417691.1A CN202111417691A CN114112936A CN 114112936 A CN114112936 A CN 114112936A CN 202111417691 A CN202111417691 A CN 202111417691A CN 114112936 A CN114112936 A CN 114112936A
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- G—PHYSICS
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Abstract
The invention discloses a device and a method for measuring components of near-wall smoke of a boiler water-cooled wall. The measuring device includes: high temperature flue gas sampling probe, light source generation portion, light absorption portion and transmission light measurement portion, wherein: the light absorption part comprises a gas absorption cell, a light incident port and a light emergent port; the flue gas outlet of the high-temperature flue gas sampling probe is connected with the gas absorption pool: and the light source generating part is connected with the light incident port, and the transmitted light measuring part is connected with the light emergent port, so that an incident light path flows through the gas absorption cell and is emergent from the light emergent port. Therefore, the light transmittance can be calculated by combining the intensity of the transmitted light measured by the transmitted light measuring part and the intensity of the light emitted by the light source generating part, and the concentration of the measured gas in the high-temperature flue gas can be further determined, so that the method can be used for evaluating the high-temperature corrosion tendency of the near-wall flue gas to the water-cooled wall of the boiler.
Description
Technical Field
The invention relates to the technical field of thermal engineering, in particular to a device and a method for measuring components of near-wall smoke of a boiler water-cooled wall.
Background
Low NO by staged blowing in furnacexCombustion technology boilers, typically suppressing NO by creating a locally reducing atmosphere by reducing the main combustion zone excess air ratioxAnd (4) generating. However, the existence of the reducing atmosphere in the furnace will cause the generation of H in the fuel such as sulfur element, nitrogen element, carbon element and the like due to oxygen deficiency combustion2S, NO, CO and other corrosive gases cause high-temperature corrosion of water-cooled walls of a main combustion area and a reduction area, and the main problem of influencing the daily safe and economic operation of a power plant is solved.
Therefore, the measurement of the components in the near-wall flue gas of the boiler water wall is needed by those skilled in the art, so as to be able to evaluate the high-temperature corrosion tendency of the near-wall flue gas to the boiler water wall.
Disclosure of Invention
The invention provides a near-wall smoke component measuring device and a near-wall smoke component measuring method, which aim to solve the problems in the prior art.
The invention provides a near-wall smoke component measuring device of a boiler water-cooled wall, which comprises: high temperature flue gas sampling probe, light source generation portion, light absorption portion and transmission light measurement portion, wherein: the light absorption part comprises a gas absorption cell, a light incident port and a light emergent port;
the flue gas outlet of the high-temperature flue gas sampling probe is connected with the gas absorption pool: and the number of the first and second groups,
the light source generating part is connected with the light incident port, and the transmission light measuring part is connected with the light emergent port, so that an incident light path flows through the gas absorption cell and is emergent from the light emergent port.
Preferably, the light absorbing portion further includes an optical lens module, and the optical lens module is configured to reflect the light beam so that the incident light path passes through the gas absorption cell and exits from the light exit port.
Preferably, the optical lens module includes: set up in the first optical lens module of gaseous absorption pond first end inner wall with set up in the second optical lens module of gaseous absorption pond second end inner wall, wherein:
the first optical lens module is used for reflecting light to the second optical lens module;
the second optical lens module is used for reflecting the light to the light exit port.
Preferably, the included angle between the optical lens in the first optical lens module and the inner wall of the first end of the gas absorption pool is 0-80 degrees; and the number of the first and second groups,
the included angle between the optical lens in the second optical lens module and the inner wall of the second end of the gas absorption tank is 0-80 degrees.
Preferably, the light source generating part includes a light source and a fiber collimator; and the number of the first and second groups,
the light source is used for emitting light to the input end of the optical fiber collimator;
the output end of the optical fiber collimator is connected with the light incident port of the light absorbing part through an optical fiber.
Based on the boiler water wall near-wall flue gas composition measuring device that this application embodiment provided, this application embodiment still provides a boiler water wall near-wall flue gas composition measuring method, measuring method includes:
measuring, by a transmitted light measuring section in the measuring device, an incident light intensity and a transmitted light intensity of a spectrum of a target wavelength;
and processing the incident light intensity and the transmitted light intensity by using a near-wall flue gas component analysis data processing method so as to determine the concentration of the detected gas in the near-wall flue gas of the boiler water-cooling wall.
Preferably, the method for analyzing and processing data of the near-wall flue gas components is used for processing the incident light intensity and the transmitted light intensity to determine the concentration of the detected gas in the near-wall flue gas of the boiler water-cooling wall, and specifically comprises the following steps: the concentration of the measured gas in the boiler water wall near-wall flue gas is determined by the following formula:
wherein, CiIs the concentration of the detected gas i; τ (λ) is a differential optical thickness calculated from the incident light intensity and the transmitted light intensity; l is the optical path of the measured gas; sigmaf(lambda) is the absorption section of the measured gas absorption quick change; λ is the target wavelength.
Preferably, the method further comprises: and (3) selecting specific waveband data to carry out least square fitting, and optimizing the concentration of the gas to be detected.
Preferably, the gas to be detected comprises CO, NO and SO2、H2S and oxygen.
Preferably, the gas to be detected comprises CO, NO and SO2、H2S, oxygenA plurality of species in the gas; and the number of the first and second groups,
the method for processing the incident light intensity and the transmitted light intensity by utilizing the near-wall flue gas component analysis data processing method to determine the concentration of the detected gas in the near-wall flue gas of the boiler water-cooling wall specifically comprises the following steps:
aiming at the problem of gas cross interference, the incident light intensity and the transmitted light intensity are processed by combining a multi-gas component comprehensive inversion method and a near-wall flue gas component analysis data processing method so as to determine the concentration of each gas in the measured gas
The measuring device comprises a high-temperature flue gas sampling probe, a light source generating part, a light absorption part and a transmission light measuring part, wherein a flue gas outlet of the high-temperature flue gas sampling probe is connected with a gas absorption cell in the light absorption part, the light source generating part is connected with a light incident port in the light absorption part, and the transmission light measuring part is connected with a light emergent port in the light absorption part, so that an incident light path flows through the gas absorption cell and is emergent from the light emergent port. Therefore, the light transmittance can be calculated by combining the intensity of the transmitted light measured by the transmitted light measuring part and the intensity of the light emitted by the light source generating part, and the concentration of the measured gas in the high-temperature flue gas can be further determined, so that the method can be used for evaluating the high-temperature corrosion tendency of the near-wall flue gas to the water-cooled wall of the boiler.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic structural diagram of a measurement apparatus according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an optical lens module in the measuring apparatus according to the embodiment of the present invention;
FIG. 3 is data of the absorbance of the flue gas components of a typical boiler in the measurement method provided in the embodiment of the present invention;
fig. 4 is a schematic diagram of a multi-gas component comprehensive inversion method provided in an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The technical solutions provided by the embodiments of the present invention are described in detail below with reference to the accompanying drawings.
As mentioned above, the low NO is achieved by staged blowing in the furnacexIn a boiler using a combustion technology, when the excess air ratio in the boiler furnace is about 0.8, the generation of NOx can be suppressed by the generated reducing gas, but the reducing gas easily corrodes the water wall of the boiler, and therefore, it is necessary to measure the flue gas around the water wall of the boiler.
For example, when the excess air ratio is about 0.8, hydrogen sulfide (H) is easily generated2S), carbon monoxide (CO), and the like, in which case oxygen (O)2) Is relatively low, and H2The higher the S and CO concentrations, the relative O2The lower the concentration, and therefore the need to measure the flue gas around the boiler waterwall (e.g., near the inner wall of the boiler waterwall), such as measuring the flue gas concentration such as H2S, CO, etc.; of course, the concentration of these reducing gases and O are taken into account2The concentration has a negative correlation relationship, and the O in the smoke can be measured2And (4) concentration.
Based on the analysis, the embodiment of the invention provides a near-wall flue gas component measuring device, which can more accurately measure the components of the near-wall flue gas of a boiler water-cooled wall and the concentration of each component, so as to solve the problems in the prior art. Of course, after the components of the near-wall flue gas of the boiler water wall and the concentrations of the components are measured, the high-temperature corrosion tendency of the near-wall flue gas to the boiler water wall can also be monitored based on the components.
As shown in fig. 1, a specific structural diagram of the measuring apparatus 1 is shown, and the measuring apparatus 1 includes: a high-temperature flue gas sampling probe 2, a light source generating part 3, a light absorbing part 4 and a transmission light measuring part 5.
Wherein, high temperature flue gas sampling probe 2 can be used for taking a sample to the high temperature flue gas. The flue gas generated by the combustion of coal in a boiler furnace usually has higher temperature, and the flue gas flows through a boiler water-cooled wall for heat exchange, so that the heat in the flue gas is recovered. In addition, after the flue gas flows through the water-cooled wall of the boiler, the flue gas can be subjected to dust removal, denitration, desulfurization and other treatments and is finally discharged into the atmosphere.
In practical application, the high-temperature flue gas sampling probe 2 can be a long and thin tubular probe, so that the high-temperature flue gas sampling probe can extend into one side of a boiler water-cooled wall close to high-temperature flue gas for sampling, namely near-wall flue gas (usually high-temperature flue gas) of the boiler water-cooled wall can be sampled through the high-temperature flue gas sampling probe 2, and the near-wall flue gas of the boiler water-cooled wall is usually higher in temperature, so that the high-temperature flue gas sampling probe 2 can be prepared by adopting high-temperature resistant materials, such as metal iron, steel and other materials with a melting point higher than the temperature of the flue gas; the high-temperature flue gas sampling probe 2 can also be prepared by adopting a high-temperature resistant ceramic material; high-temperature resistant coatings can also be generated on the inner surface and the outer surface of the slender tubular probe made of other materials, so that the high-temperature flue gas sampling probe 2 is obtained, and the high-temperature resistant coatings can be made of high-temperature resistant ceramic or metal materials.
The light source generating part 3 can be used to emit light, and the gas to be detected (referred to as the detected gas) in the high-temperature flue gas is usually H2S, CO, etc., and different gases have different absorption patterns of molecules and atoms. Therefore, in order to make the light emitted from the light source generating unit 3 absorbed by the gas to be measured in the flue gas as much as possible, the frequency (or wavelength) of the light emitted from the light source generating unit 3 can be further generally represented by H2S, CO, and oxygen, and absorption spectrum of at least one molecule.
For example, H2The absorption spectrum of the S molecule is mainly in the ultraviolet region, especially the ultraviolet region of 180-400 nm, so the wavelength of the light emitted by the light source generating part 3 can also be in the ultraviolet region of 180-400 nm, thereby the H in the high-temperature smoke can be detected2S, the light emitted from the light source generating part 3 can be H as much as possible2S absorption, so that the detection sensitivity is improved; the absorption spectra of CO and oxygen are mainly in the infrared region, and therefore, when the gas to be measured is CO or oxygen, the wavelength of the light emitted from the light source generating section 3 is mainly in the infrared region.
The light absorption part 4 comprises a gas absorption cell 46, a light inlet and a light outlet, wherein the smoke outlet of the high-temperature smoke sampling probe 2 is connected with the gas absorption cell 46, the light inlet in the light absorption part 4 is connected with the light source generation part 3, and the transmission light measurement part 5 is connected with the light outlet. Thus, when detecting the detected gas in the high-temperature flue gas, the high-temperature flue gas can enter the gas absorption cell 46 through the flue gas outlet of the high-temperature flue gas sampling probe 2, and the light emitted by the light source generating part 3 can enter the light absorbing part 4 through the light incident port, so that the incident light path flows through the gas absorption cell 46, and in the gas absorption cell 46, the incident light (i.e. the light entering from the light incident port) is absorbed by the detected gas in the high-temperature flue gas and then emitted from the light emitting port.
The light emitted from the light source generator 3 enters from the light entrance port of the light absorber 4, passes through the gas absorption cell 46 on the optical path, is absorbed by the gas to be measured in the high-temperature flue gas, and is emitted to the transmitted light measuring unit 5 through the light exit port, and the intensity of the light is measured by the transmitted light measuring unit 5.
In this way, the light transmittance (I1/I0) that is inversely related to the concentration of the gas to be measured can be calculated from the intensity of the light measured by the transmitted light measuring unit 5 (referred to as I1) and the intensity of the light emitted by the light source generating unit 3 (referred to as I0). When the concentration of the gas to be measured is measured, a standard curve of the concentration and the light transmittance can be drawn, then the light transmittance of the high-temperature flue gas is measured, and the concentration of the gas to be measured in the high-temperature flue gas is determined by combining the standard curve.
With the measuring device 1 provided by the embodiment of the present invention, the measuring device 1 includes the high-temperature flue gas sampling probe 2, the light source generation part 3, the light absorption part 4 and the transmission light measurement part 5, wherein the flue gas outlet of the high-temperature flue gas sampling probe 2 is connected to the gas absorption cell 46 in the light absorption part 4, the light source generation part 3 is connected to the light entrance port in the light absorption part 4, and the transmission light measurement part 5 is connected to the light exit port in the light absorption part 4, so that the incident light path flows through the gas absorption cell 46 and exits from the light exit port. Therefore, the light transmittance can be calculated by the intensity of the transmitted light measured by the transmitted light measuring part 5 and the intensity of the light emitted by the light source generating part 3, and the concentration of the gas to be measured in the high-temperature flue gas can be further determined.
In practical applications, the gas absorption cell 46 may be a White cell, a Herriott cell, or other type of gas absorption cell, but is not limited thereto.
In practical application, the coal-fired boiler usually contains dust, moisture and the like in the high-temperature flue gas generated in the combustion process of coal, and the dust and the moisture may influence the intensity of incident light, so that the measurement accuracy is influenced, and therefore, the high-temperature flue gas dedusting system 21 and/or the high-temperature flue gas dewatering system 22 can be arranged in the high-temperature flue gas sampling probe 2, so that the dust and/or the moisture in the high-temperature flue gas are removed, and the measurement accuracy is improved.
For example, can set up high temperature flue gas dust pelletizing system 21 in high temperature flue gas sampling probe 2 and remove dust, perhaps also can set up high temperature flue gas dewatering system 22 in high temperature flue gas sampling probe 2 and carry out the dewatering, perhaps also can set up high temperature flue gas dust pelletizing system 21 and high temperature flue gas dewatering system 22 in high temperature flue gas sampling probe 2 to remove dust earlier, then remove water.
In addition, for the high-temperature flue gas after dust and/or moisture removal, because the temperature of the high-temperature flue gas is relatively high (and the temperatures of the high-temperature flue gases in different batches are different), in order to reduce the influence of the temperature of the high-temperature flue gas on the measurement accuracy, a heat exchange system 23 may be further provided in the high-temperature flue gas sampling probe 2, for example, after the high-temperature flue gas is dedusted by the high-temperature flue gas dedusting system 21 and is dewatered by the high-temperature flue gas dewatering system 22, the temperature of the high-temperature flue gas is regulated and controlled by using the heat exchange system 23, for example, the temperature is regulated and controlled (mainly, the temperature of the high-temperature flue gas is reduced) to a certain specified temperature or a specified temperature interval, for example, 20 to 100 ℃, so that the subsequent measurement is facilitated and the influence of the temperature on the measurement accuracy is reduced.
In practical applications, the high temperature flue gas dust removal system 21 may include a dust removal device 211, a dust amount measurement device 212, and a dust amount feedback device 213. Wherein, the dust removing device 211 is used for removing dust from the high-temperature flue gas; the dust amount measuring device 212 is used for measuring the content of dust in the high-temperature flue gas, for example, by measuring the weight of the dust removed by the dust removing device 211, so as to calculate the content of dust in the high-temperature flue gas; the dust amount feedback device 213 is connected to the dust amount measuring device 212, and is configured to feed back the measured content of dust in the high-temperature flue gas, for example, to a display device to display the dust content, where the dust content can reflect the quality and combustion condition of coal in the coal-fired boiler, so as to guide the combustion of coal.
Usually, the dust removing device 211 can be generally composed of a small cyclone tube group a and a filter cartridge dust remover B, and can utilize the small cyclone tube group a to perform primary-effect dust removal at one level, and then utilize the filter cartridge dust remover B to perform secondary-effect dust removal, so as to realize multi-level removal of dust in high-temperature flue gas.
The high temperature flue gas water removal system 22 may include a water removal device 221, a flue gas humidity detection device 222, and a flue gas humidity feedback device 223. Wherein, the dewatering device 221 can be a barrel-packed or bag-packed phosphoric acid granule, so that the phosphoric acid granule is used for absorbing the moisture in the high-temperature flue gas; the flue gas humidity detection device 222 can be used for detecting the humidity of the high-temperature flue gas, for example, the flue gas humidity detection device 222 can be a humidity meter or other devices with similar functions; the flue gas humidity feedback device 223 is connected with the flue gas humidity detection device 222, and is used for feeding back the detected humidity of the high-temperature flue gas, for example, feeding back the detected humidity to a display device, and because the humidity of the high-temperature flue gas can reflect the coal quality and the combustion condition in the coal-fired boiler, the flue gas humidity feedback device 223 can also be used for guiding the combustion of coal.
As mentioned above, the light transmittance can be calculated from the intensity I1 of the light measured by the transmitted light measuring unit 5 by using the I1, and the concentration of the gas to be measured in the high-temperature flue gas can be determined by using the light transmittance. In practical application, after the I1 is obtained, the light transmittance can be calculated in a manual calculation mode, and then the concentration of the gas to be detected is calculated; in general, in order to improve efficiency, a reducing gas concentration measurement feedback device 6 may be added to the measurement device 1, and a data input end of the reducing gas concentration measurement feedback device 6 is connected to the transmitted light measurement unit 5, so that the intensity I1 of light measured by the transmitted light measurement unit 5 can be obtained, the light transmittance can be calculated by using the I1, and the concentration of the measured gas in the high-temperature flue gas can be determined. The reducing gas concentration measurement feedback device 6 may be generally a computer that receives the intensity I1 of the light measured by the transmitted light measurement unit 5, calculates the light transmittance, and determines the concentration of the gas to be measured in the high-temperature flue gas. In order to facilitate the feedback of the concentration of the measured gas in the high-temperature flue gas calculated by the computer, the reducing gas concentration measurement feedback device 6 may further include a signal forwarding device D, and the signal forwarding device D obtains the calculation result of the computer and performs feedback.
In addition, the high temperature flue gas water removal system 22 may further include a heat tracing band C, and the heat tracing band C is connected to the data input end of the reducing gas concentration measurement feedback device 6 and the flue gas humidity feedback device 223, so as to control the actual heating power and the like of the heat tracing band C according to the concentration of the measured gas in the high temperature flue gas and the humidity of the high temperature flue gas. Generally, the heat tracing band C may be an electric heat tracing band or the like.
Particularly, when the actual heating power of the heat tracing band C is increased and the detected concentration of the detected gas is basically stable, it indicates that the moisture in the high-temperature flue gas is not condensed but is sufficiently absorbed by the high-temperature flue gas water removal system 22, so that the influence of the moisture on the measurement accuracy is further eliminated, and the actual heating power of the heat tracing band C at the moment reaches a better state.
In practical applications, the transmitted light measuring part 5 may be embodied as a spectrometer, and the transmitted light measuring part 5 and the light exit port of the light absorbing part 4 may be connected by an optical fiber. The spectrometer can be a high-resolution spectrometer or a low-resolution spectrometer, and the high-resolution spectrometer or the low-resolution spectrometer can be selected according to the self characteristics of the gas to be measured and the surrounding environment due to the fact that the bandwidths of the spectrums measurable by the spectrometers with different resolutions are different.
The light source generating unit 3 may generally include a light source 31 and a fiber collimator 32, wherein the light source 31 is configured to emit light to an input end of the fiber collimator 32, and an output end of the fiber collimator 32 is connected to the light incident port of the light absorbing unit 4 through an optical fiber, so that the light emitted from the light source 31 is incident to the light incident port of the light absorbing unit 4 through the fiber collimator 32.
Considering that the measured gas is usually H2S, CO, the light source 31 can be an ultraviolet light source 311 and/or an infrared light source 312, for example, the ultraviolet light source 311 can be a deuterium lamp to emit ultraviolet light with a continuous spectrum, and the window of the deuterium lamp can be made of UV glass capable of transmitting ultraviolet light of 180-400 nm.
The infrared light source 312 may be a laser, thereby emitting infrared light. Furthermore, the laser 312 can emit two beams of light with different wavelengths through the optical fiber coupler, the laser linewidth is small, the spectral line extraction of a single spectral line is accurate, and the current tuning frequency is low.
In order to make the incident light path pass through the gas absorption cell 46 and exit from the light exit port in practical use, an optical lens module 45 may be additionally arranged in the light absorption portion 4 for reflecting the incident light via the optical lens module 45, so that the incident light path passes through the gas absorption cell 46 and exits from the light exit port.
As shown in fig. 2, the optical lens module 45 may generally include a first optical lens module 451 and a second optical lens module 452, the first optical lens module 451 may be disposed on an inner wall of a first end of the gas absorption cell 46, and the second optical lens module 452 may be disposed on an inner wall of a second end of the gas absorption cell 46, so that incident light is reflected to the second optical lens module 452 through the first optical lens module 451, and the reflected light is further reflected to a light exit port through the second optical lens module 452, so that an optical path is increased through two reflections of the first optical lens module 451 and the second optical lens module 452, and thus an absorption degree of light is increased, and a detection sensitivity is improved. The incident light is reflected by the first optical lens module 451 to the optical path of the second optical lens module 452, and flows through the gas absorption cell 46, so as to be absorbed by the high temperature flue gas in the gas absorption cell 46.
In addition, the light absorption part 4 further includes a gas transport pipe 41, so that the high temperature flue gas sampling probe 2 is connected to the gas absorption cell 46 through the gas transport pipe 41, and the collected high temperature flue gas is transported to the gas absorption cell 46. In order to discharge the gas in the gas absorption cell 46, a gas transport pipe 42 is further included in the light absorption portion 4, and the gas transport pipe 42 is connected to a second end of the gas absorption cell 46, thereby discharging the smoke after the measurement.
In order to enable the first optical lens module 451 to reflect the incident light to the second optical lens module 452, an included angle a between an optical lens of the first optical lens module 451 and the inner wall of the first end of the gas absorption cell 46 may be 0 to 80 degrees, such as 0 degree, 30 degrees, 45 degrees, 60 degrees, 75 degrees, 80 degrees, and the like; correspondingly, the included angle b between the optical lens of the second optical lens module 452 and the inner wall of the second end of the gas absorption cell 46 may also be 0 to 80 degrees, such as 0 degree, 30 degrees, 45 degrees, 60 degrees, 75 degrees, 80 degrees, and the like.
In addition, a heating temperature control device 43 and a pressure sensor 44 may be further disposed in the light absorption portion 4, the heating temperature control device 43 may be used to control the temperature of the flue gas in the cavity of the gas absorption cell 46, and the pressure sensor 44 is used to measure the pressure in the cavity of the gas absorption cell 46.
Based on the near-wall smoke component measuring device provided by the invention, a near-wall smoke component measuring device method can also be provided, and the method comprises the following steps: and then the incident light intensity and the transmitted light intensity of the target wavelength spectrum are processed by using a near wall flue gas component analysis data processing method, so that the concentration of the detected gas in the near wall flue gas of the boiler water wall is determined.
Of course, after the concentration of the detected gas in the boiler water wall near-wall flue gas is determined, the high-temperature corrosion tendency of the near-wall flue gas on the boiler water wall can be evaluated according to the concentration of the detected gas.
The specific size of the target wavelength can be determined according to the measured gas, such as H2S, the absorption spectrum of the material is mainly in an ultraviolet region, particularly in the ultraviolet region of 180-400 nm, so that the target wavelength can be 180-400 nm and the like, and the target wavelength spectrum can be a spectrum with the wavelength of 180-400 nm; alternatively, when the gas to be measured is CO or oxygen, the target wavelength may be a certain range of the infrared region or the like, considering that the absorption spectra of CO and oxygen are mainly in the infrared region. Of course, the measured gas may also be H2S, CO, oxygen, such as H2S and CO as the gas to be measured, or H2S, CO and oxygen as the gas to be measured, the target wavelength may be a plurality of different wavelengths.
After the incident light intensity and the transmitted light intensity of the target wavelength spectrum are measured by the transmitted light measuring part, the processing of the incident light intensity and the transmitted light intensity by using the near-wall flue gas component analysis data processing method may include the following modes:
the incident light intensity and the transmitted light intensity conform to the relationship of the following formula (1):
I(λ)＝I0(λ)exp[-σ(λ)CL]formula (1)
In the formula (1), I (lambda) is the transmitted light intensity of the transmitted light with the wavelength lambda after the light emitted by the light source generating part passes through the measured gas, I (lambda) is0(λ) is the intensity of incident light with a wavelength of λ (usually called initial intensity) in the light emitted from the light source generator, L is the optical path length of the measured gas, C is the concentration of the measured gas, and σ (λ) is the absorption cross section of the measured gasThe facet is typically associated with a wavelength λ.
Therefore, the concentration C of the measured gas can be calculated by the above formula (1).
Considering not only the absorption of light by the measured gas, but also the extinction by rayleigh scattering and mie scattering, which causes the change in light intensity, the formula (1) can be further modified to the following formula (2):
in the formula (2), epsilon is newly added relative to the formula (1)R(λ) is the Rayleigh scattering extinction coefficient, ∈M(λ) is the Mie scattering extinction coefficient.
Therefore, the concentration C of the measured gas can also be calculated by the above formula (2), and the calculated concentration C of the measured gas is more accurate because the influence caused by rayleigh scattering and mie scattering is corrected in the formula (2).
In addition, when the gas to be measured is a plurality of gases, for example, H2S, CO, and oxygen, wherein the above formula (2) can be further modified to formula (3):
in formula (3), σ is relative to formula (2)iDenotes the absorption cross section of the ith gas, and Ci denotes the concentration of the ith gas. Thus, the concentrations of a plurality of gases are simultaneously measured by analyzing overlapping absorption spectra of the gases in the same wavelength band.
Because the gas absorption comprises two parts of 'slow change' and 'fast change', as shown in formula (4):
σ(λ)＝σs(λ)+σf(lambda) formula (4)
In the formula (4), σs (Lambda) is the gas absorption slow-changing absorption cross-section, sigmaf(lambda) gas absorption quick-change absorption cross section.
Thus, a wide-band absorption and a narrow-band absorption can be obtained, and the following formula (5) can be obtained by further correcting the above formula (3):
therefore, the optical thickness OD is calculated by equation (6):
in the formula (6), the first and second groups,
is broadband absorption, i.e., broadband absorption due to broadband absorption and scattering in gas absorption, which can be removed from the optical thickness by analysis;
is caused by narrow-band absorption, i.e., gas absorption, from which the differential optical thickness τ (λ) can be calculated by equation (7):
and then, eliminating the influence of other flue gases on the gas to be detected through the optimal waveband, calculating the concentration of other gases, and finally obtaining the differential optical thickness only related to the gas to be detected. From this, a flue gas absorbance profile can be obtained, as shown in FIG. 3 for typical boiler flue gas composition absorbance data.
Therefore, the measured gas concentration can be calculated by equation (8):
in order to reduce the influence of system noise and other factors on the calculation result, the concentration of the optimized measured gas can be obtained by selecting specific waveband data and performing least square fitting as shown in formula (9):
in formula (9), AiRepresenting the actual measured absorbance. And finding the minimum difference sum r to obtain the optimized measured gas concentration C.
The gas to be detected comprises CO, NO and SO2、H2S and one or more of oxygen, and the gas concentration calculation is carried out according to different specific wave bands to carry out selection processing to obtain corresponding results.
Aiming at CO, NO and SO in near-wall flue gas2、H2S, the problem of interference of gases such as oxygen and the like can be solved, and the incident light intensity and the transmitted light intensity can be processed by combining a multi-gas component comprehensive inversion method and a near-wall flue gas component analysis data processing method so as to determine the concentration of each gas in the detected gas.
The steps of the multi-gas component comprehensive inversion method, as shown in fig. 4, include:
firstly, selecting experimental data of a specific wave band I, wherein the wave band is only absorbed by a single gas (called as gas A), and calculating to obtain the concentration C of the gas AA(ii) a Wherein the gas A can be CO, NO, SO2、H2S and oxygen.
Then, selecting the experimental data of a specific wave band II, wherein the wave band is the absorption superposition of two gases (the ratio is gas A and gas B), and calculating the concentration C of the gas A according to the step IACalculating the absorption signal of the gas A in the specific waveband II, and correcting by overlapping the absorption signals to obtain the absorption signal of the gas B in the specific waveband II so as to calculate the concentration C of the gas BB(ii) a Wherein the gas B is CO, NO, SO2、H2S, oxygen, a gas different from the gas A.
Then, selecting the experimental data of a specific wave band III, wherein the wave band is three gases (the ratio of the gas A to the gas A is the gas A, and the ratio of the gas A to the gas A is the gas AThe absorption of the body B and the gas C) are superposed, and the concentration C of the gas A is calculated according to the steps I and IIAWith concentration C of gas BBCalculating absorption signals of the gas A and the gas B in the specific waveband III, and correcting by overlapping the absorption signals to obtain an absorption signal of the gas C in the specific waveband III so as to calculate and obtain the concentration C of the gas CC(ii) a Wherein the gas C is CO, NO, SO2、H2S, oxygen, a gas different from gas a and gas B.
Certainly, even if the measured gas also contains other gases, the concentration of various gases in the measured gas can be determined through the same idea and iterative solution can be carried out one by one, and finally the components of the near-wall flue gas can be determined.
It is to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in the process, method, article, or apparatus that comprises the element.
The above are merely examples of the present invention, and are not intended to limit the present invention. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (10)
1. A near wall flue gas composition measuring device of a boiler water wall is characterized by comprising: high temperature flue gas sampling probe (2), light source generation portion (3), light absorption portion (4) and transmitted light measurement portion (5), wherein: the light absorption part (4) comprises a gas absorption cell (46), a light entrance port and a light exit port;
the flue gas outlet of the high-temperature flue gas sampling probe (2) is connected with the gas absorption pool (46): and the number of the first and second groups,
the light source generating part (3) is connected with the light entrance port, and the transmitted light measuring part (5) is connected with the light exit port, so that an incident light path flows through the gas absorption cell (46) and exits from the light exit port.
2. The measuring device according to claim 1, wherein the light absorbing portion (4) further comprises an optical lens module (45) for causing an incident light path to flow through the gas absorption cell (46) and exit from the light exit port by reflection of the optical lens module (45).
3. The measuring device according to claim 2, wherein the optical lens module (45) comprises: a first optical lens module (451) arranged on the inner wall of the first end of the gas absorption cell (46) and a second optical lens module (452) arranged on the inner wall of the second end of the gas absorption cell (46), wherein:
the first optical lens module (451) for reflecting light to the second optical lens module (452);
the second optical lens module (452) is used for reflecting the light to the light exit port.
4. The measuring apparatus according to claim 3, wherein the optical lens of the first optical lens module (451) forms an angle of 0 to 80 degrees with the inner wall of the first end of the gas absorption cell (46); and the number of the first and second groups,
the included angle between the optical lens in the second optical lens module (452) and the inner wall of the second end of the gas absorption cell (46) is 0-80 degrees.
5. The measuring device according to claim 1, wherein the light source generating section (3) includes a light source and a fiber collimator; and the number of the first and second groups,
the light source is used for emitting light to the input end of the optical fiber collimator;
the output end of the optical fiber collimator is connected with the light incident port of the light absorbing part (4) through an optical fiber.
6. A method for measuring the components of flue gas near the wall of a water cooled wall of a boiler based on the measuring device of any one of claims 1 to 5 is characterized by comprising the following steps:
measuring, by a transmitted light measuring section in the measuring device, an incident light intensity and a transmitted light intensity of a spectrum of a target wavelength;
and processing the incident light intensity and the transmitted light intensity by using a near-wall flue gas component analysis data processing method so as to determine the concentration of the detected gas in the near-wall flue gas of the boiler water-cooling wall.
7. The measurement method according to claim 6, wherein the incident light intensity and the transmitted light intensity are processed by a near-wall flue gas component analysis data processing method to determine the concentration of the measured gas in the near-wall flue gas of the boiler water-cooled wall, specifically comprising: the concentration of the measured gas in the boiler water wall near-wall flue gas is determined by the following formula:
wherein, CiIs the concentration of the detected gas i; τ (λ) is a differential optical thickness calculated from the incident light intensity and the transmitted light intensity; l is the optical path of the measured gas; sigmaf(lambda) is the absorption section of the measured gas absorption quick change; λ is the target wavelength.
8. The measurement method of claim 6, wherein the method further comprises: and (3) selecting specific waveband data to carry out least square fitting, and optimizing the concentration of the gas to be detected.
9. The measurement method of claim 6, wherein the measurement method is performed by a computerThe gas to be detected comprises CO, NO and SO2、H2S and oxygen.
10. The method of claim 9, wherein the gas to be measured comprises CO, NO, SO2、H2S, a plurality of oxygen; and the number of the first and second groups,
the method for processing the incident light intensity and the transmitted light intensity by utilizing the near-wall flue gas component analysis data processing method to determine the concentration of the detected gas in the near-wall flue gas of the boiler water-cooling wall specifically comprises the following steps:
and aiming at the problem of gas cross interference, combining a multi-gas component comprehensive inversion method and a near-wall smoke component analysis data processing method to process the incident light intensity and the transmitted light intensity so as to determine the concentration of each gas in the detected gas.
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