JP7794573B2 - Method for detecting sulfide corrosion sites, device for detecting sulfide corrosion sites, and fluorescent substance or phosphorescent substance for detecting sulfide corrosion sites - Google Patents

Description

The present invention relates to a detection method and detection device for detecting areas where sulfide corrosion will occur or where sulfide corrosion has already occurred in metal components used in heat transfer tubes of coal-burning boilers and gasifiers. The present invention also relates to a fluorescent substance or phosphorescent substance for detecting areas where sulfide corrosion will occur or where sulfide corrosion has already occurred, which can detect areas where sulfide corrosion will occur or where sulfide corrosion has already occurred.

In recent years, thermal power plants that burn pulverized coal have adopted two-stage combustion for the purpose of low-NOx operation, due to environmental considerations and other factors. It is known that low-NOx operation can cause sulfidation corrosion of boiler heat transfer tubes due to reducing combustion gases. Patent Document 1 discloses that ZnS (zinc sulfide) is concentrated in the ash that adheres to areas that have been corroded by sulfidation.

Elemental analysis methods such as EPMA and XRF can be used to measure the concentrations of Zn and S contained in ash. Zn and S do not necessarily exist as ZnS (for example, S can exist as PbS), but if Zn is present in a significant concentration, it will exist as ZnS and may be causing sulfide corrosion. Therefore, by measuring the Zn concentration in ash collected from the boiler, or in ash that remains attached to the boiler, it can be determined that areas of the heat transfer tubes where ash containing high concentrations of Zn has adhered are areas where sulfide corrosion is occurring.

Elemental analysis methods are applied to measurement points on ash that has adhered widely to heat transfer tubes, so they are not efficient for measuring Zn concentrations over a wide area. Furthermore, it is unclear whether the concentration measured is the maximum value around the measurement point or an average value. To address these issues, measuring Zn concentrations at multiple measurement points is one option. However, this still requires measurements at each measurement point, and it cannot be said to be an efficient way to comprehensively measure Zn concentrations over a wide area. Another option is for an experienced technician to identify areas that appear to be corroded by sulfide and then perform measurements at those locations, but this method relies on human experience and therefore lacks reliability.

This problem exists not only when detecting sulfide-corroded areas such as heat transfer tubes in boilers or gasifiers in thermal power plants that burn pulverized coal, but also when detecting metal components with deposits on their surfaces.

Japanese Patent Application Laid-Open No. 2012-2551

Shuji Mori, Satoru Kakitani, Hiroshi Miyake, Kazuhiro Yamaguchi, Phase transition and fluorescence spectrum in the Zn2SiO2-Mn2Si04 system, 1994, Bulletin of Okayama University of Science. A, Natural Sciences, 30, 115-120(1994), http://id.nii.ac.jp/1182/00001100/ Wentao Zhang, Hong-Ro Lee, Synthesis and luminescence properties of Zn(Cu(0.01) Cd(0.02) Mg(0.02))S phosphor, April 12, 2011, The journal of biological and chemical luminescence, https://doi.org/10.1002/bio.1190 Tatsuya Ueda, Synthesis of Mn-doped ZnS nanoparticles using a solution method and fabrication of EL devices, March 2012, Master's thesis, Faculty of Engineering, Gunma University, http://hdl.handle.net/10087/8502 Tetsuhiko Isobe, High Luminescence Efficiency of Doped Nanocrystals by Silica Surface Modification, July 19, 2011, Journal of the Illuminating Engineering Institute of Japan, Vol. 87, No. 4, 2003, pp. 256-261, https://doi.org/10.2150/jieij1980.87.4_256 Tetsuhiko Isobe, Luminescence Mechanism and Local Structure Analysis of Organic/Inorganic Hybrid ZnS:Mn Nanocrystal Phosphors, October 27, 2007, Surface Science Vol. 22, No. 5, pp. 315-322, 2001, https://doi.org/10.1380/jsssj.22.315 Ginya Adachi, Phosphors used in color television cathode ray tubes (<Special Issue> Progress in Display Materials), August 20, 1990, Chemistry and Education 1990, Vol. 38, No. 4, pp. 386-390, https://doi.org/10.20665/kakyoshi.38.4_386 Wageh, S., Ternary ZnS:Te nanoparticles capped with 3-mercaptopropionic acid prepared in aqueous media,2016, Journal of Materials Science: Materials in Electronics; 27, 10; 10877-10887; 2016, https://doi.org/10.1007/s10854-016-5197-7 Masashi Shirata, "Study on the creation and luminescence properties of novel zinc sulfide phosphors activated with iridium and related metals," Shizuoka University, Doctoral dissertation, (2011). http://doi.org/10.14945/00006522 Kotera Yoshihide, Naraoka Kiyotaka, Electrophotoluminescence of Zinc Sulfide Phosphors, April 12, 2006, Bulletin of the Chemical Society of Japan Vol.33, Issue 6, https://doi.org/10.1246/bcsj.33.721 Srinivasa Buddhudu, Hong Xi Zhang, Chan Hin Kam, Seng Lee Ng, Boon Siew Ooi, Yee Loy Lam, Yuen Chuen Chan, Yan Zhou, Wenxiu Que, Terence Kin Shun Wong,Green and red luminescence in Tb3+ and Eu3+:Zn2SiO4 powders, April 13, 2000, Proceedings Volume 3942, Rare-Earth-Doped Materials and Devices IV; (2000), https://doi.org/10.1117/12.382881 Koji Inoue, Minetomo Masuda, Fabrication of thin films of wide bandgap ZnO phosphors by cation doping, 2011, Mie Prefectural Industrial Research Institute Research Report (36), 1-4, 2011, https://www.pref.mie.lg.jp/common/content/000172058.pdf Yang Li, Yiyang Li, Ruchun Chen, Kaniyarakkal Sharafudeen, Shifeng Zhou, Mindaugas Gecevicius, Haihui Wang, Guoping Dong, Yiling Wu, Xixi Qin and Jianrong Qiu, Tailoring of the trap distribution and crystal field in Cr3+-doped non-gallate phosphors with near-infrared long-persistence phosphorescence, May 22, 2015, NPG Asia Materials volume 7, page 180(2015), https://doi.org/10.1038/am.2015.38 Dongqiang Han, Low-temperature synthesis and photoluminescence properties of oriented ZnAl2O4 nanowire arrays, August 4, 2017, Superlattices and Microstructures Volume 111, November 2017, Pages 1093-1098, https://doi.org/10.1016/j.spmi.2017.08.012

In view of the above circumstances, the primary object of the present invention is to provide a method and device for detecting sulfide-corroded areas that can detect sulfide-corroded areas over a wide area. Another object of the present invention is to provide a fluorescent substance or phosphorescent substance for detecting sulfide-corroded areas that can detect corroded areas.

In the present invention, "sulfide corrosion occurs or has occurred in a part of the component (hereinafter referred to as the covered part) covered by the luminescent part of the deposit (hereinafter referred to as the luminescent part)" means that sulfide corrosion has not yet occurred in the covered part but there is a possibility that sulfide corrosion will occur in the future, or that sulfide corrosion has already occurred.

In the present invention, the light emitted from the light-emitting site is fluorescence or phosphorescence. In the following explanation, the term "fluorescence" refers to either fluorescence or phosphorescence. Similarly, "fluorescent material" refers to a fluorescent substance or phosphorescent material.

The present invention can be used to detect sulfidation corrosion in any metal component. Examples of such components include boilers that burn pulverized coal and heat transfer tubes in gasifiers that gasify and burn coal.

To achieve the above objective, one aspect of the present invention is a method for detecting areas of sulfide corrosion, which involves irradiating ultraviolet light onto an attachment attached to the surface of a metal member, and determining that sulfide corrosion has occurred or is occurring in the coated area of the member covered by the light-emitting area of the attachment if the fluorescence emitted from the attachment includes a first peak wavelength in the wavelength band of 500 nm or more and 550 nm or less.

Another aspect of the present invention for achieving the above object is a detection device for areas of sulfide corrosion, comprising: an ultraviolet light source that irradiates ultraviolet light onto attachments attached to the surface of a metal member; a spectroscopic measurement unit that measures the spectroscopic spectrum of the fluorescence emitted from the attachments; and a determination unit that, if the spectroscopic spectrum includes a first peak wavelength of 500 nm or more and 550 nm or less, determines that sulfide corrosion has occurred in the area of the member covered by the light-emitting portion of the attachment.

Another aspect of the present invention to achieve the above object is a sulfide corrosion detection phosphor or sulfide corrosion detection phosphor, which comprises a zinc compound containing Zn as the main component and at least one element selected from the group consisting of Mn, Cu, Cd, Ag, Au, Cl, Ir, Te, Fe, Pb, Tb, Eu, Mg, and Cr, and is excited by ultraviolet light to emit fluorescence having a first peak wavelength in the wavelength band of 500 nm or more and 550 nm or less, and is formed on the surface of a metal member.

Another aspect of the present invention for achieving the above object resides in a phosphor for detecting sulfide corrosion sites, which contains _ZnAl2O4 or _ZnMgO as a zinc compound containing Zn as a main component, is excited by ultraviolet light to emit fluorescence having a first peak wavelength in a wavelength band of 500 nm or more and 550 nm or less, and is formed on the surface of a metal member.

The present invention provides a method and device for detecting sulfide-corroded areas that can detect areas that have been corroded by sulfide over a wide area. The present invention also provides a phosphor for detecting sulfide-corroded areas that can detect corroded areas.

FIG. 1 is a schematic diagram of a detection device for a sulfide corrosion site. 1A and 1B are a plan view and a cross-sectional view illustrating light emitted from ash attached to a heat transfer tube. FIG. 1 is a diagram showing the results of EPMA analysis. FIG. 1 is a photograph showing a sample that emits orange fluorescence.

The following drawings will be used to explain a method and device for detecting sulfide corrosion areas according to an embodiment of the present invention. In addition, to supplement the explanation of colors and color development, color drawings corresponding to Figures 3 to 5 will be attached to the project submission form and submitted.

This embodiment describes the case where sulfidation corrosion occurs or is determined to have occurred in heat transfer tubes of a boiler that burns coal or a gasifier that gasifies and burns coal.

Fig. 1 is a schematic diagram of a detection device for detecting sulfidation corrosion sites. Fig. 2(a) is a plan view illustrating the light emitted from ash attached to a heat transfer tube, and Fig. 2(b) is a cross-sectional view taken along line A-A of Fig. 1.
1, the detection device 1 is used to detect sulfidation corrosion sites that have occurred on a boiler heat transfer tube 10 (an example of a component recited in the claims). Ash 11 (an example of an attachment recited in the claims) adheres to the heat transfer tube 10 as a result of the combustion of pulverized coal.

The detection device 1 includes an ultraviolet light source 2, a camera 3, and a determination unit 4. The ultraviolet light source 2 may be a device equipped with an ultraviolet LED that emits ultraviolet light, or a device configured to extract ultraviolet light by applying a bandpass filter to a xenon mercury lamp. The wavelength of the ultraviolet light is not particularly limited, but it may be any light with a peak in the wavelength range of 200 nm to 430 nm. Wavelengths from 200 nm to 400 nm are ultraviolet light, and wavelengths around 430 nm are violet light. As described below, it is assumed that even violet light with wavelengths longer than ultraviolet light can produce fluorescence, so an ultraviolet light source capable of emitting ultraviolet light can be used. Hereinafter, "ultraviolet light" is defined as "ultraviolet light or violet light with a peak in the wavelength range of 200 nm to 430 nm." The camera 3 measures the spectrum of the received light and is an example of a spectroscopic measurement unit described in the claims. Other spectroscopic measurement units that can be used include a spectrometer, a camera with a bandpass filter, and a photodetector with a bandpass filter. The determination unit 4, details of which will be described later, is an information processing device that analyzes the spectroscopic spectrum to detect areas of sulfide corrosion.

The method for detecting sulfide corrosion areas on boiler heat transfer tubes 10 is carried out as follows. During regular inspections, for example, an ultraviolet light source 2 is brought into the boiler, and as shown in Figure 2, ultraviolet light is emitted from the ultraviolet light source 2 at any location on the heat transfer tube 10. The ultraviolet light may be emitted without touching the heat transfer tube 10, or the ash 11 may be wiped away to a certain extent before the ultraviolet light is emitted. When the ultraviolet light is emitted, orange fluorescence can be seen from some of the ash 11.

As will be described in more detail below, the fluorescence has a first peak wavelength in the wavelength band of 500 nm to 550 nm. The fluorescence also has a second peak wavelength in the wavelength band of 600 nm to 700 nm. Fluorescence of these wavelengths can be seen as orange from the light-emitting site 12. Note that "visible from the light-emitting site 12" here does not only mean that the fluorescence can be seen from the light-emitting site 12 exposed after the ash 11 has been removed, but also means that the light-emitting site 12 is covered to some extent by ash 11 and the fluorescence can be seen from above the ash 11.

If fluorescence from such a light-emitting portion 12 can be visually confirmed, the portion of the heat transfer tube 10 covered by that light-emitting portion 12 (hereinafter referred to as the covered portion 13) is determined to be a portion where sulfide corrosion has occurred in a concave shape. The light emitted from the light-emitting portion 12 is considered to be fluorescence or phosphorescence.

Note that the detection method of the present invention is not limited to irradiating ultraviolet light onto ash 11 adhering to the heat transfer tube 10. Ash 11 may also be collected from the heat transfer tube 10 and then irradiated with ultraviolet light. If a light-emitting portion 12 can be visually confirmed on the ash 11 after ultraviolet light irradiation, it is determined that sulfide corrosion has occurred in the coated portion 13 of the heat transfer tube 10 where the ash 11 was adhering.

Here, we will explain the composition of the luminescent areas. Ash attached to the heat transfer tubes of a boiler that burns coal in actual operation was irradiated with ultraviolet light, and luminescent areas that were visually confirmed to be emitting light from the ash were collected and used as samples. Elemental analysis (hereafter referred to as EPMA) was performed on the samples using an electron probe microanalyzer. The results are shown in Figure 3, which shows an image in which each element is color-coded according to its concentration. Zn and S are shown in pink, indicating high concentrations, within dotted ellipses. In other words, the EPMA results revealed that high concentrations of Zn and S were present in the luminescent areas.

The sample was ash adhering to the heat transfer tubes of a coal-fired boiler. This sample was irradiated with ultraviolet light, and the fluorescence emitted by the ultraviolet light was received by camera 3 to obtain a spectrum. The fluorescence was visually recognized as orange. The ultraviolet light was obtained by applying a bandpass filter that transmits ultraviolet light to a xenon mercury lamp. The bandpass filter was a HOYA U340 bandpass filter. The results are shown in Figure 4.

Figure 4(a) shows the spectrum of the excitation light source (ultraviolet light), and Figure 4(b) shows the spectrum of the fluorescence obtained from the sample. The horizontal axis is wavelength, and the vertical axis is emission intensity.

As shown in Figure 4(a), the ultraviolet light spectrum (UV) has a peak in the wavelength range of 200 nm to 430 nm. A peak is also observed in the wavelength range of 650 nm to 800 nm, which is likely the result of reflection from the sample.

As shown in Figure 4(b), the spectrum Fo of the orange fluorescence emitted from the sample had a first peak in the wavelength range of 500 nm to 550 nm, and extended over the wavelength range of 460 nm to 700 nm. This suggests that the sample may contain a substance that emits fluorescence with the first peak. Furthermore, peaks were observed before and after the first peak, which were similar to the spectral spectrum of ultraviolet light and were therefore considered to be the spectral spectrum of ultraviolet light.

Furthermore, the intensity slope of spectrum Fo changed in the wavelength range from 600 nm to 700 nm. This suggests that the sample may contain a substance that emits fluorescence with a peak (hereinafter referred to as the second peak) in this wavelength range.

Non-Patent Document 1 discloses that (Zn-Mn) _2SiO4 emits light having a spectrum similar to the spectrum Fo shown in FIG. ₄ and a first peak similar to that shown in FIG. 4. Non-Patent Document 2 discloses that Zn(Cu,Cd,Mg)S emits light having a first peak similar to the spectrum Fo shown in FIG. 4. Non-Patent Documents 3 to 5 disclose that ZnS:Mn emits fluorescence having a peak near 600 nm. Non-Patent Document 6 discloses that ZnS:Ag emits fluorescence having a peak at 465 nm, and ZnS:Au,Cu,Al emits fluorescence having a peak at 539 nm. Non-Patent Document 7 discloses that ZnS:Te emits fluorescence having a peak at 439 nm. Non-Patent Document 8 discloses that ZnS:Cl and ZnS:Cl,Ir emit fluorescence having peaks at 440 to 450 nm and 515 nm. Non-Patent Document 9 describes that ZnS:Ag, (Zn,Cd)S:Ag, ZnS:Cu, (ZnCd)S:Cu, ZnS:CuFe, ZnS:Cu,Pb, ZnS:Pb,Mn, ZnS:Mn, ZnS, ZnO:Mn, (Zn,Cd)S:Mn, and Zn(S,Se):Cu emit light. Non-Patent Document 10 describes that Tb ³⁺ :Zn ₂ SiO ₄ emits fluorescence with a peak at 543 nm, and Eu ³⁺ :Zn ₂ SiO ₄ emits fluorescence with a peak at 612 nm. Non-Patent Document 11 describes that ZnMgO emits fluorescence with a peak between 400 nm and 500 nm. Since Mg is contained in an amount of 10% or more, it is considered a major component rather than a trace element. Non-Patent Document ₁₂ describes that _Zn2SnO4 :Cr and Zn _{(2-x) Al2xSn (1-x) O4} :Cr emit fluorescence with a peak at 800 nm in the wavelength range from 650 _nm to 1200 nm. Non-Patent Document 13 describes that _ZnAl2O4 emits light centered at 500 nm.

Table 1 shows the luminescent materials described in the above-mentioned non-patent documents, as well as their main components and trace elements.

Summarizing the above results, the EPMA results indicated that the material constituting the light-emitting region 12 contained a high concentration of Zn, suggesting that it was primarily composed of Zn. Furthermore, Patent Document 1 states that ZnS affects sulfidation corrosion, and a comparison of the spectroscopic spectrum with Non-Patent Documents 1-13 suggests that the material is primarily composed of a zinc compound. The zinc compound is at least one selected from the group consisting of ZnS, ZnCdS, Zn( _S ,Se), and zinc oxide. The zinc oxide is at least one selected from the group consisting of _Zn2SiO4 , _ZnO , ZnMgO, _Zn2SnO4 , Zn _{(2-x) Al2xSn (1-x) O4 ,} and _ZnAl2O4 . Furthermore, Tb and Eu described in Non-Patent Document 10 emit light when contained as trace substances _{in Zn2SiO4} , but although it is not clear from each Non-Patent Document whether they also emit light when contained in a main component other _{than Zn2SiO4} (for example, ZnS), it was presumed that they would emit light even if contained in other main components. Similarly, it was presumed that trace elements other than Tb and Eu would emit light even if contained in the main components listed in Table 1.

Based on a comparison of the spectroscopic spectra and Non-Patent Documents 1 to 13, it was thought that trace elements (e.g., Mn, Cu, Cd, Ag, Au, Cl, Ir, Te, Fe, Pb, Tb, _Eu , Mg, Cr) may contribute to the fluorescence emission, with Mn and Cu being particularly likely to contribute. Furthermore, it was thought that _ZnAl2O4 and ZnMgO may emit light even without containing trace elements.

Therefore, it was estimated that the luminescent site 12 (fluorescent substance or phosphor for detecting sulfide corrosion sites) contains a zinc compound and at least one trace element selected from the group consisting of Mn, Cu, Cd, Ag, Au, Cl, Ir, Te, Fe, Pb, Tb, Eu, Mg, and Cr. Alternatively, it was estimated that the luminescent site 12 is _ZnAl2O4 or _ZnMgO , which is a zinc compound.

It is generally known that excitation becomes stronger as the excitation wavelength becomes shorter. For example, using deep ultraviolet light around 200 nm strengthens excitation and increases the intensity of light emission. However, as shown in Figure 4, it has been found that samples can emit sufficient fluorescence even with ultraviolet light around 400 nm or purple light around 430 nm, which are not deep ultraviolet light. Deep ultraviolet light can be obtained using a xenon mercury lamp, but this tends to require a large-scale device configuration. On the other hand, ultraviolet light around 400 nm and purple light around 430 nm can also be obtained with ultraviolet LEDs. For this reason, ultraviolet LEDs, which are cost-effective and portable, can be used as an ultraviolet light source to excite samples.

Figure 5 shows an example of the fluorescence emitted from the sample. Figure 5 is a photograph showing a sample emitting orange fluorescence. The sample in Figure 5 is ash adhering to the surface of a boiler extruded tube material. The surface of the sample that was in contact with the heat transfer tube 10 is shown.

Figure 5(a) shows the sample before it was exposed to UV light, and Figure 5(b) shows the sample after it has been exposed to UV light. The ovals in the photograph indicate the areas that glow orange. As shown in the figure, before UV light was applied, the area indicated by the oval was indistinguishable from the areas outside of that area. However, when UV light was applied to the sample, an area that glowed orange could be seen within the purple irradiated area indicated by the oval. Furthermore, sulfide corrosion had occurred in a portion (coated area 13 in Figure 2) of the base material (heat transfer tube 10 in Figure 2) covered by this orange-emitting area (light-emitting area 12 in Figure 2).

As explained above, the method for detecting sulfide corrosion areas of the present invention irradiates ultraviolet light onto ash 11 attached to the surface of the heat transfer tube 10, and if the fluorescence emitted from the ash 11 is visually recognized as orange, i.e., if the fluorescence includes a first peak wavelength in the wavelength band of 500 nm or more and 550 nm or less, it is determined that sulfide corrosion has occurred or is occurring in the coated area 13 covered by the ash 11.

By irradiating the heat transfer tube 10 with ultraviolet light and observing the fluorescence emitted from the ash 11, it is possible to detect areas where sulfide corrosion is occurring or where there is a high risk of sulfide corrosion progressing in the future. Conventionally, sulfide corrosion areas were identified using measurement points as targets, but with the detection method of the present invention, ultraviolet light is irradiated over a certain area of the surface of the heat transfer tube 10, making it possible to detect sulfide corrosion areas on a surface-by-surface basis. This allows for more efficient detection of sulfide corrosion areas than conventional methods. Furthermore, because sulfide corrosion areas are detected on a surface-by-surface basis, it is also possible to resolve a conventional problem, such as the uncertainty of whether the ZnS concentration in the sulfide-corroded area is the maximum value or the average value. Furthermore, because detection of sulfide corrosion areas is based on visual observation of the fluorescence emitted from the ash 11, it can be performed reliably without relying on the experience of a skilled operator.

Furthermore, if the fluorescence includes a first peak wavelength in the wavelength band of 500 nm or more and 550 nm or less, and further includes a second peak wavelength in the wavelength band of 600 nm or more and 700 nm or less, it is determined that sulfide corrosion has occurred in the coated portion 13 covered with ash 11. This makes it possible to determine that sulfide corrosion has occurred or is occurring in the coated portion 13 covered with ash 11.

Orange fluorescence with the above-mentioned wavelength can be seen by irradiating ultraviolet light on ash 11 that remains attached to the heat transfer tube 10, or on ash 11 that has been partially wiped off. Therefore, compared to completely removing the ash 11 and directly checking for sulfide corrosion on the heat transfer tube 10, the effort required to remove the ash 11 can be saved, and the location of sulfide corrosion can be determined in a shorter time.

In addition to detecting sulfide corrosion areas by visually observing the fluorescence with the naked eye, sulfide corrosion areas may also be detected by analyzing the spectral spectrum. An example of such a device configuration is the detection device 1, as described in FIG. 1, which includes an ultraviolet light source 2, a camera 3, and a determination unit 4. The determination unit 4 is an information processing device that analyzes the spectral spectrum measured by the camera 3. Specifically, if the spectral spectrum contains a first peak wavelength in the wavelength range of 500 nm to 550 nm, the determination unit 4 determines that sulfide corrosion has occurred in the coated portion 13 of the heat transfer tube 10 covered by the light-emitting portion 12 emitted by the ash 11. Furthermore, if the spectral spectrum contains a second peak wavelength in the wavelength range of 600 nm to 700 nm, the determination unit 4 determines that sulfide corrosion has occurred in the coated portion 13 of the heat transfer tube 10 covered by the light-emitting portion 12 emitted by the ash 11. This detection device 1 achieves the same effects as the detection method described above.

The light-emitting portion 12 (hereinafter also referred to as sulfide corrosion site detection phosphor) includes a zinc compound primarily composed of Zn and at least one element selected from the group consisting of Mn, Cu, Cd, Ag, Au, Cl, Ir, Te, Fe, Pb, Tb, Eu, Mg, and Cr, and is excited by ultraviolet light to emit fluorescence having a first peak wavelength in a wavelength band of 500 nm to 550 nm. Because the sulfide corrosion site detection phosphor emits the above fluorescence in response to ultraviolet light, it can be used to detect sulfide corrosion sites in the coating portion 13 on which the sulfide corrosion site detection phosphor is formed. A sulfide corrosion site detection phosphor that includes _ZnAl2O4 or _ZnMgO , which is a zinc compound primarily composed of Zn, and that is excited by ultraviolet light to emit fluorescence having a first peak wavelength in a wavelength band of 500 nm to 550 nm can also be used to detect sulfide corrosion sites.

In particular, the detection device configured with a drone equipped with an ultraviolet light source 2 and camera 3, as described below, eliminates the need for a device configuration for removing ash 11, thereby reducing costs, and can be completed in a shorter time than methods for determining areas of sulfide corrosion that require the removal of ash 11.

The above describes one embodiment of the present invention, but of course the present invention is not limited to the above embodiment, and additions, omissions, substitutions, and other modifications to the configuration are possible without departing from the spirit of the present invention.

In the above embodiment, the detection of sulfide corrosion areas on a boiler heat transfer tube was described, but the present invention is not limited to this example. The present invention can also be applied to components made of any metal and deposits attached to the surface of those components.

The ultraviolet light source and spectroscopic measurement unit, such as a camera, may also be mounted on a drone. For example, the ultraviolet light source and camera are mounted on a drone, and the drone is flown inside the boiler while irradiating the heat transfer tubes with ultraviolet light and capturing the fluorescence with the camera. The obtained spectrum may be stored in a storage device mounted on the drone, or transmitted to a monitor or evaluation unit separate from the drone via wireless communication means mounted on the drone. Of course, an evaluation unit composed of a microcomputer or the like may be mounted on the drone to evaluate sulfide corrosion areas on the spot. Such a drone-type detection device or a detection method using the detection device makes it easy to irradiate ultraviolet light and measure fluorescence on areas located high in the boiler.

1...Detection device, 2...Ultraviolet light source, 3...Camera, 4...Determination unit

Claims (5)

UV light is irradiated onto the deposits on the surface of the metal member,
When the fluorescence emitted from the attachment includes a first peak wavelength in a wavelength band of 500 nm or more and 550 nm or less, it is determined that sulfide corrosion has occurred or is occurring in the coated portion of the component that is covered by the light-emitting portion of the attachment,
the member is a heat transfer tube of a boiler that burns fuel in a reducing atmosphere,
The deposit is ash that has adhered to the heat transfer tube.
A method for detecting a sulfide corrosion site, comprising: The method for detecting a sulfide corrosion site according to claim 1,
and determining that sulfide corrosion has occurred or is occurring in a coated area of the component that is covered by the fluorescent portion of the attachment when the fluorescence emitted from the attachment includes a second peak wavelength in a wavelength band of 600 nm or more and 700 nm or less. an ultraviolet light source that irradiates ultraviolet light onto deposits attached to the surface of a metal member;
a spectroscopic measurement unit that measures the spectroscopic spectrum of the fluorescence emitted from the attachment;
a determination unit that determines that sulfide corrosion has occurred in a coated area of the member that is covered by the light-emitting portion of the attachment when the spectrum includes a first peak wavelength of 500 nm or more and 550 nm or less ,
the member is a heat transfer tube of a boiler that burns fuel in a reducing atmosphere,
The deposit is ash that has adhered to the heat transfer tube.
A detection device for detecting sulfide corrosion sites. The detection device for a sulfide corrosion site according to claim 3 ,
the determination unit determines that sulfide corrosion has occurred in a coated region of the component that is covered by the light-emitting portion of the attachment when the spectrum further includes a second peak wavelength of 600 nm or more and 700 nm or less. A zinc compound containing Zn as a main component and at least one selected from the group consisting of Mn, Cu, Cd , and Mg ,
When excited by ultraviolet light, the fluorescent material emits fluorescence having a first peak wavelength in a wavelength band of 500 nm or more and 550 nm or less and a second peak wavelength in a wavelength band of 600 nm or more and 700 nm or less;
A fluorescent substance for detecting sulfide corrosion sites or a phosphorescent substance for detecting sulfide corrosion sites, which is formed on the surface of a metal member.