JP6251941B2 - boiler - Google Patents

Description

  The present invention relates to, for example, a boiler provided in a thermal power plant and having a plurality of heat transfer tubes.

In a power generation boiler of a thermal power plant, steam is heated by several superheaters. The superheater has a large number of heat transfer tubes, and superheats the steam passing through the inside of the tubes from the outside of the heat transfer tubes by the high-temperature exhaust gas of the boiler. The steam that has been heated by the high-temperature exhaust gas from the boiler and has passed through a large number of heat transfer tubes is arranged in the upper part of the boiler and collects in the header in the ceiling housing where the high-temperature exhaust gas does not flow. The header is a non-heated part and collects the superheated steam from the heat transfer tubes of the boiler via a number of nozzles.
When the boiler superheater is mixed with obstacles such as foreign matter, the steam flow is inhibited. If the flow of steam is inhibited, high-temperature gas heats the surface of the heat transfer tube from the outside of the heat transfer tube, while the amount of fluid inside is reduced, which is not preferable.

As a method for monitoring the state of the boiler superheater, a method is known in which the temperature of the nozzle, which is a non-heating unit, is measured by a thermocouple and the temperature is monitored.
For example, Patent Document 1 describes a method of measuring the temperature distribution of an object at a high temperature using an optical fiber.

JP-A-8-145810

By the way, the thermocouple can measure only one point per one (one pair) from the principle of temperature detection, and monitoring the temperature of the total number of heat transfer tubes is not realistic in terms of cost and construction. In addition, it is not realistic because of the structure for taking out the thermocouple out of the boiler.
Therefore, at present, thermocouples are arranged only at the representative points of the non-heated part of the nozzle, and the temperature is monitored and whether there is an abnormally overheated part is monitored based on the temperature tendency. However, there is a problem that abnormal overheating cannot be detected if the location where the foreign matter is clogged is different from the heat transfer tube monitoring the temperature.

  Moreover, in the method of patent document 1, when the measurement object is discrete, such as a some heat exchanger tube, there exists a subject that a measurement becomes difficult.

  An object of the present invention is to provide a boiler that can efficiently measure temperatures of a plurality of heat exchange tubes and facilitates replacement of optical fibers.

According to the first aspect of the present invention, the boiler is arranged so as to extend in the juxtaposition direction of the plurality of heat exchange tubes and the plurality of heat exchange tubes arranged in parallel with each other. A protective tube fixed to be in contact with the heat exchange tube, an optical fiber inserted into the protective tube so that it can be inserted and removed, an incident pulse transmission device for injecting laser pulse light into the optical fiber, and the laser pulse light And an analyzer for analyzing the time, wavelength, and light intensity until returning as backscattered light.

  According to such a configuration, since the optical fibers are arranged so as to extend in the direction in which the heat exchange tubes are arranged, it is possible to efficiently measure the temperature of the plurality of heat exchange tubes by the analyzer. Since the optical fiber can be exchanged via the protective tube, the maintenance becomes easy, and the type of optical fiber and the measurement method can be easily changed.

The boiler has a thermocouple attached to at least one of the plurality of heat exchange tubes, and the analysis device uses the temperature measured by the thermocouple, the time, wavelength, and light. It is good also as a structure which calibrates the temperature measured by analyzing an intensity | strength.
According to such a structure, the temperature measurement of the several heat exchange tube by an analyzer can be performed more correctly.

The boiler may include an interposition member disposed between the protective tube and the optical fiber and having a predetermined heat transfer coefficient.
According to such a configuration, the optical fiber can be protected by the interposed member, and the temperature measured using the heat transfer coefficient of the interposed member can be corrected.

The said boiler WHEREIN: The said protective tube is good also as a structure meandering with the same pitch as the said space | interval of these heat exchange tubes.
According to such a configuration, even when the protective tube is thermally contracted, the expansion and contraction of the protective tube can be absorbed.
In the boiler, the protective tube includes fixing brackets that respectively fix the protective tube to the plurality of heat exchange tubes so that one of the protective tubes is in contact with the plurality of heat exchange tubes. You may meander so that it may curve in the extension direction of the said heat exchange tube between the said fittings which fit.
In the boiler, the fixing bracket may be secured to the plurality of protective tubes by a binding band or a wire.

  According to the present invention, since the optical fibers are arranged so as to extend in the direction in which the heat exchange tubes are arranged side by side, it is possible to efficiently measure the temperature of the plurality of heat exchange tubes by the analyzer. Since the optical fiber can be exchanged via the protective tube, the maintenance becomes easy, and the type of optical fiber and the measurement method can be easily changed.

It is a perspective view of the boiler of a first embodiment of the present invention. It is a perspective view which shows the header vicinity of 1st embodiment of this invention. It is a perspective view explaining the structure of the protective tube and optical fiber of 1st embodiment of this invention. It is sectional drawing explaining the fixing method of the protective tube of the optical fiber of 1st embodiment of this invention. It is a side view explaining the installation method of the protective tube of the optical fiber of 1st embodiment of this invention. It is a top view explaining the modification of the installation method of the protective tube of the optical fiber of 1st embodiment of this invention. It is a side view explaining the modification of the installation method of the protective tube of the optical fiber of 1st embodiment of this invention. It is a graph which shows the example of a measurement of Rayleigh scattered light, Raman scattered light, and Brillouin scattered light. It is sectional drawing explaining the fixing method of the protection tube of the optical fiber of 2nd embodiment of this invention. It is a side view explaining the modification of the installation method of the protective tube of the optical fiber of 3rd embodiment of this invention.

(First embodiment)
Hereinafter, the boiler 1 of 1st embodiment of this invention is demonstrated in detail with reference to drawings.
The boiler 1 of this embodiment is the boiler 1 provided in a thermal power plant, for example. As shown in FIG. 1, a plurality of superheaters 3 and reheaters (only one superheater 3 is shown in FIG. 1) are provided in the flue 2 at the top of the boiler 1. The superheater 3 has an inlet header 4a and an outlet header 4b, and a plurality of heat transfer tubes 6 (heat exchange tubes) connected thereto. The combustion gas G rises while swirling, heats the wall tube of the boiler 1, and heats the plurality of heat transfer tubes 6 arranged in the flue 2.

As shown in FIG. 2, the header 4 is disposed above the ceiling wall 7 of the boiler 1, and the plurality of heat transfer tubes 6 constitute a nozzle 8 above the ceiling wall 7. The plurality of heat transfer tubes 6 are disposed in the flue 2 (see FIG. 1) through the ceiling wall 7. The plurality of heat transfer tubes 6 are welded to the header at the root portion of the nozzle base 8. The heat transfer tubes 6 constituting the nozzle base 8 are arranged in several tens of rows in parallel with each other in the axial direction of the header 4. In other words, the plurality of heat transfer tubes 6 are arranged side by side so that the plurality of heat transfer tubes 6 are parallel to each other.
A boiler ceiling housing 9 is provided on the ceiling wall 7 of the boiler 1. The boiler ceiling housing 9 is a space that is isolated from the internal space of the boiler 1 and does not allow combustion gas that passes through the flue 2 to flow in.

An optical fiber 11 for measuring the temperature of the heat transfer tube 6 is disposed in the plurality of heat transfer tubes 6 constituting the nozzle base 8 of the present embodiment. The optical fiber 11 is arranged so as to extend in the parallel arrangement direction S (the axial direction of the header 4) of the plurality of heat transfer tubes 6, and is disposed inside a metal protective tube 12 fixed so as to contact the heat transfer tube 6. Has been placed. The optical fiber 11 is inserted through the protective tube 6 so as to be removable.
Here, the juxtaposed direction is a direction in which a plurality of heat transfer tubes 6 are arranged. Since the plurality of heat transfer tubes 6 of this embodiment are arranged so as to be parallel to each other, the juxtaposition direction is a direction orthogonal to the extending direction of the heat transfer tubes 6.

The optical fiber 11 is disposed in the vicinity of the plurality of heat transfer tubes 6 by a protection tube 12 that functions as a guide tube, and is protected by the protection tube 12 that is a tubular member.
The protective tube 12 is made of, for example, a metal such as SUS316, which is a stainless steel material with improved corrosion resistance. The diameter of the protective tube 12 is a dimension according to the diameter of the optical fiber 11, and the diameter of the protective tube 12 of this embodiment is about 3.2 mm.

The protective tube 12 is inserted into the boiler ceiling housing 9 through a through hole 13 formed in the boiler ceiling housing 9.
The optical fiber 11 is inserted into the protective tube 12 from the first end 11a, which is the terminal, and the second end 11b opposite to the first end 11a is connected to the optical fiber measuring instrument 14. Yes.
The optical fiber measuring instrument 14 has a function as an incident pulse transmission device that makes laser pulse light, which is pulsed laser light, incident on the optical fiber 11. The optical fiber measuring instrument 14 has a function as a backscattered light receiving device that receives backscattered light of laser pulse light.
The optical fiber measuring instrument 14 is connected to a data processing PC 15 that is an analyzer. The data processing PC 15 is a computer that analyzes time, wavelength, and light intensity until the laser pulse light returns as backscattered light.

As shown in FIG. 3, the optical fiber 11 includes a core 17 that is a core through which light propagates, a concentric clad 18 that covers the periphery of the core 17, a polyimide coating 19 that covers the cladding 18, and an outer periphery of the polyimide coating 19. And a metal tube 20 covering the side. The core 17 and the clad 18 are formed of a dielectric (quartz glass or plastic) that is two kinds of transparent and has a high light transmittance. The refractive index of the cladding 18 is made smaller than the refractive index of the core 17. Thereby, the optical signal is confined in the core 17 and transmitted using the total reflection phenomenon of light.
The polyimide coating 19 is a coating having high heat resistance (up to 300 ° C.) and chemical resistance.
The metal tube 20 is a tube for further protecting the optical fiber 11 from the outer peripheral side of the polyimide coating 19. For example, a flexible tube made of stainless steel or Incoloy (registered trademark) can be adopted.

Next, a fixing method when the protective tube 12 is fixed to the heat transfer tube 6 will be described.
As shown in FIG. 4, the protective tube 12 is fixed by a metal fixing bracket 21 and a binding band 22 (cable tie) that fixes the fixing bracket 21 to the outer peripheral surface of the heat transfer tube 6. The fixing bracket 21 is fixed by winding the binding band 22 in the circumferential direction of the tubular heat transfer tube 6.
The fixture 21 includes a fixture main body 23 having a U-shaped cross section that contacts the protective tube 12 through a plurality of contact points, and band insertion portions 24 provided at both ends of the fixture main body 23. Has been. The band insertion part 24 has a hole through which the binding band 22 can be inserted.

The binding band 22 is a belt-like restraining member formed of a metal such as stainless steel, for example. A locking part is attached to the first end of the binding band 22. When the binding band 22 is used, the second end opposite to the first end of the binding band 22 is passed through the locking component. The binding band 22 is not limited to metal, and may be made of resin as long as the required heat resistance and the like can be satisfied.
Note that the method of fixing the protective tube 12 is not limited to this, and for example, a method of securing the protective tube 12 using the wire 26 may be employed.

  Further, the glass wool tape 25 is wound around the protective tube 12 at the fixed location. The glass wool tape 25 is fixed to the heat transfer tube 6 by a wire 26, and is bonded by an adhesive (for example, Aron ceramic) which has excellent heat resistance and high adhesive strength even at high temperatures.

As shown in FIG. 5, the protective tube 12 is formed to meander. The protective tube 12 is formed so as to meander in one direction in the extending direction L (vertical direction) of the heat transfer tube 6 and in the opposite direction. In other words, the protective tube 12 is not formed linearly toward the parallel arrangement direction S of the heat transfer tubes 6 (a direction orthogonal to the extending direction of the heat transfer tubes 6).
Specifically, the protective tube 12 meanders so as to curve upward (or downward) between adjacent heat transfer tubes 6. That is, the protective tube 12 meanders at the same pitch as the interval between the adjacent heat transfer tubes 6.

  The meandering direction of the protective tube 12 is not limited to the vertical direction. As shown in FIG. 6, the structure may meander in the horizontal direction H. Specifically, the protective tube 12 may be meandered so as to be bent laterally between the adjacent heat transfer tubes 6.

Further, as shown in FIG. 7, the protective tube 12 (optical fiber 11) may meander along the heat transfer tube 6 within a predetermined range. The portion along the heat transfer tube 6 of the protective tube 12 is preferably bonded with an adhesive 27 such as Aron ceramic. By adhering in this way, the protective tube 12 and the heat transfer tube 6 can be more closely attached. Such an arrangement method is particularly effective in the Raman scattered light measurement method described later.
The protective tube 12 is laid on the ceiling housing by the method as described above.

Next, the nozzle temperature measuring method in the above boiler 1 will be described.
First, laser pulse light is incident on the optical fiber 11 by the incident pulse transmission device of the optical fiber measuring instrument 14. The laser pulse light incident on the optical fiber 11 generates scattered light at each passing position of the optical fiber 11.
As shown in FIG. 8, the scattered light includes Rayleigh scattered light having the same wavelength as the incident light, Raman scattered light different from the incident light, and Brillouin scattered light. Raman scattered light is divided into Stokes light having a longer wavelength than incident light and anti-Stokes light having a shorter wavelength than incident light. It has been confirmed that the intensity ratio between the Stokes light and the anti-Stokes light has a certain relationship with the temperature of the optical fiber 11 where the scattered light is generated.
The Brillouin scattered light is known to shift in frequency according to the deformation (temperature and strain) of the optical fiber 11, and the change in the state of the optical fiber 11 can be known.

  On the other hand, part of the scattered light generated in each part of the optical fiber 11 returns to the incident position again as backscattered light. Therefore, the position where the scattered light is generated can be found by measuring the time when it returns as the back scattered light after the incident pulse light is incident. Next, the temperature of each position can be found by analyzing the wavelength and light intensity of the backscattered light returning to the incident position one after another.

The data processing PC 15 serving as an analyzer measures the temperature of the optical fiber 11 and the strain of the optical fiber 11 using the characteristics as described above.
For example, the temperature of the heat transfer tube 6 can be measured using ROTDR (Raman Optical Time Domain Reflectmeter).
Further, the strain and temperature of the heat transfer tube 6 can be measured using BOTDR (Brillouin Optical Time Domain Reflectmeter).

Moreover, the distortion and temperature of the heat exchanger tube 6 can be measured using a FBG (Fiber Bragg Grating, Bragg wavelength measuring method) by providing a diffraction grating in the optical fiber 11 in advance.
Since the protective tube 12 is interposed between the optical fiber 11 and the heat transfer tube 6, the data processing PC 15 calculates the temperature in consideration of the temperature drop due to the protective tube 12. Specifically, the temperature measured by the optical fiber 11 is corrected using the heat transfer coefficient of SUS304 and the plate thickness of the protective tube 12 constituting the protective tube 12.
In addition, various optical fiber 11 sensing measurement methods can be employed.

  According to the said embodiment, since the optical fiber 11 is arrange | positioned so that it may extend in the juxtaposition direction of the heat exchanger tube 6, the temperature measurement of the some heat exchanger tube 6 by the data processing PC15 which is an analyzer can be performed efficiently. .

In addition, since the optical fiber 11 can be exchanged via the protective tube 12, maintenance is facilitated, and the type of the optical fiber 11 and the measurement method can be easily changed.
Further, since the protective tube 12 has a meandering shape, even when the protective tube 12 is thermally contracted, the expansion and contraction of the protective tube 12 can be absorbed.

In addition, in the boiler 1 of the said embodiment, although the protective tube 12 shall be formed integrally, it does not restrict to this. For example, the protective tube 12 may be divided at a pitch of 2 m, and the divided protective tubes 12 may be connected to each other using a joint. Thereby, the protection tube 12 can be easily removed at the time of maintenance of the nozzle 8.
Moreover, in the said embodiment, although the structure which has the polyimide coating 19 and the metal tube 20 was shown as a structure of the optical fiber 11, it does not restrict to this. For example, the optical fiber 11 that does not have the metal tube 20 may be employed.

(Second embodiment)
Hereinafter, a boiler according to a second embodiment of the present invention will be described with reference to the drawings. In the present embodiment, differences from the first embodiment described above will be mainly described, and description of similar parts will be omitted.
As shown in FIG. 9, an interposition member 28 made of ceramic is disposed between the optical fiber 11 and the protective tube 12 of the present embodiment. As a material for forming the interposition member 28, for example, a material having a predetermined heat transfer coefficient that can reduce the temperature transmitted to the optical fiber 11 to about 300 ° C. when the protective tube 12 is heated to 600 ° C. preferable. If the heat transfer rate is too high, heat is not sufficiently transmitted to the optical fiber 11, which is not preferable.

  The data processing PC 15 (see FIG. 2), which is an analysis device, calculates the temperature by weighing the temperature drop due to the interposition member 28. Specifically, the temperature measured by the optical fiber 11 is corrected using the heat transfer coefficient of the ceramic constituting the interposed member 28 and the plate thickness of the interposed member 28.

  According to the embodiment, the optical fiber 11 can be protected by the interposed member 28, and the temperature measured using the heat transfer coefficient of the interposed member 28 can be corrected.

(Third embodiment)
Hereinafter, a boiler according to a third embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 10, a sheathed thermocouple 29 and a pad-type thermocouple 31 are attached to the heat transfer tube 6 of the boiler of this embodiment. Specifically, the sheath thermocouple 29 is disposed at a predetermined position inside the protective tube 12. The temperature measuring contact 30 of the sheath thermocouple 29 is installed, for example, at a position far from the heat transfer tube 6 (point A) or a position closest to the heat transfer tube 6 (point B). The sheath thermocouple 29 is connected to the data processing PC 15 (see FIG. 2).
The data processing PC 15 compares the temperature by the sheath thermocouple 29 at the points A and B with the temperature by the optical fiber 11 and determines the correction amount. Then, the data processing PC 15 corrects the temperature at other measurement points measured by the optical fiber 11 using the determined correction amount.

  A pad surface 32 that is a measurement surface of the pad type thermocouple 31 is directly attached to the heat transfer tube 6. The pad type thermocouple 31 is connected to the data processing PC 15. That is, the pad type thermocouple 31 is not disposed inside the protective tube 12.

According to the embodiment, the temperature measured by the optical fiber 11 can be corrected by grasping the more accurate temperature using the thermocouples 29 and 31. Further, when the sheath thermocouple 29 is used, the thermocouples 29 and 31 can be easily arranged via the protective tube 12.
Further, when the pad type thermocouple 31 is used, more accurate correction can be performed because the temperature of the heat transfer tube 6 can be measured more accurately.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations of the embodiments in the embodiments are examples, and the addition and omission of configurations are within the scope not departing from the gist of the present invention. , Substitutions, and other changes are possible. Further, the present invention is not limited by the embodiments, and is limited only by the scope of the claims.
For example, in each said embodiment, although the temperature and distortion of the heat exchanger tube 6 of the nozzle base 8 of the boiler 1 were measured, it does not restrict to this. For example, the temperature and strain of the evaporator tube on the furnace wall of the boiler 1 may be measured.

1 boiler 2 flue 3 superheater 4 header 4a inlet header 4b outlet header 6 heat transfer tube (heat exchange tube)
7 ceiling wall 8 nozzle 9 boiler ceiling housing 11 optical fiber 11a first end 11b second end 12 protective tube 13 through hole 14 optical fiber measuring instrument (incident pulse transmitter)
15 Data processing PC (analyzer)
17 Core 18 Cladding 19 Polyimide coating 20 Metal tube 21 Fixing bracket 22 Binding band 23 Fixing bracket body 24 Band insertion part 25 Glass wool tape 26 Wire 28 Interposition member 29 Sheath thermocouple 30 Temperature measuring contact 31 Pad type thermocouple 32 Pad surface S Parallel direction

Claims (6)

A plurality of heat exchange tubes juxtaposed at intervals, and
A protective tube that is arranged so as to extend in the direction in which the plurality of heat exchange tubes are juxtaposed, and is fixed so as to contact the plurality of heat exchange tubes;
An optical fiber inserted into the protective tube in a detachable manner;
An incident pulse transmission device that makes laser pulse light incident on the optical fiber;
A boiler comprising: an analysis device that analyzes time, wavelength, and light intensity until the laser pulse light returns as backscattered light. A thermocouple attached to at least one of the plurality of heat exchange tubes;
The boiler according to claim 1, wherein the analyzer calibrates the temperature measured by analyzing the time, wavelength, and light intensity using the temperature measured by the thermocouple.   The boiler according to claim 1 or 2, further comprising an interposition member disposed between the protective tube and the optical fiber and having a predetermined heat transfer coefficient.   The boiler according to any one of claims 1 to 3, wherein the protective tube meanders at the same pitch as the interval between the plurality of heat exchange tubes.   A fixing fitting for fixing the protection tube to the plurality of heat exchange tubes, respectively, so that one of the protection tubes is in contact with the plurality of heat exchange tubes;
  The boiler according to any one of claims 1 to 4, wherein the protective tube is meandering so as to bend in a direction in which the heat exchange tube extends between the adjacent fixing fittings.   The boiler according to claim 5, wherein the fixing bracket is secured to the plurality of protective tubes by a binding band or a wire.

Images