JPS61134644A - Steam monitor equipment of steam turbine - Google Patents

Abstract

PURPOSE:To measure distribution of a grain diameter and grain density of a waterdrop within a steam turbine accurately by constituting a probe with the tip part of an optical fiber for irradiation, an optical system and the tip part of an optical fiber for photodetection. CONSTITUTION:Monochromatic laser light emitted from a laser light source is led into the optical fiber 4 for irradiation and covered by a light shielding pipe 25 and formed of a collimated laser beam of a prescribed cross section by a collimator lens 27 via the tip part of the fiber 4 bent in U-shape so as to turn the proceeding or the laser light by 180 deg.. Then, when the laser light C is irradiated on a measuring area P passing through the optical system, the laser light C is scattered by steam R to be measured and made incident on each of the optical fibers 51-5n for photodetection as the scattered light C' taking a task of measuring information. The scattered light C' at each scattered angle led to the outside of the steam turbine by each of the fibers 51-5n is converted photoelectrically by a detector and inputted to an arithmetic unit and the distribution of the grain diameter and the grain density of the waterdrop within the steam turbine are calculated.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a steam turbine in which the efficiency of a steam turbine and the immersion state of rotor blades are determined and monitored from the particle size distribution and particle density of water droplets in the steam. The present invention relates to a turbine steam monitoring device.

[Technical background of the invention and its problems]

Commercial thermal power turbines, nuclear power turbines, geothermal turbines, etc. are operated using so-called wet steam, which contains water droplets in the steam. To know the efficiency of such a steam turbine, it is necessary to know the energy of wet steam, that is, the sum of the energy of steam and the energy of water droplets. Since the energy possessed by water droplets is derived from the amount of water droplets, it is impossible to determine the accurate efficiency of a steam turbine unless the amount of water droplets is known.

However, in the past, there was no way to accurately measure the amount of water droplets, so the efficiency of a steam turbine had to be estimated from the plant's electrical output, drain amount, etc., which lacked accuracy. .

On the other hand, this type of steam turbine has a problem in that water droplets contained in the steam cause 1IIJIll of corrosion.

like this! F! In order to prevent flooding of 1 meter, it is essential not only to improve the material of the rotor blades and the structure of the steam turbine, but also to operate the turbine in proper conditions. Allowing erosion of rotor blades under design operating conditions @ (lilIX-
Fl,, mechanic o, yuo, 5 uh, ah. 8.1 If the matching between the turbine inlet steam condition and the load is insufficient during partial load operation or load fluctuations, or if the steam condition fluctuates transiently, the steam humidity may increase abnormally, etc. This may lead to excessive erosion of the rotor blades.

Therefore, there is a need for a device that can quantitatively monitor steam humidity at all times. However, steam wetness is also determined from the amount of water droplets in the steam turbine, and as there is no way to determine this, it is also impossible to accurately determine the amount of erosion on the rotor blades. Ta.

[Purpose of the invention]

The present invention was made based on these facts,
An object of the present invention is to provide a steam monitoring device for a steam turbine that can monitor the efficiency of the steam turbine and the corrosion state of the rotor blades by understanding the particle size distribution and particle density of water droplets in the steam.

[Summary of the invention]

In general, when a spherical particle with a particle diameter is irradiated with parallel monochromatic light such as a laser beam, the scattered light intensity 1 (D
, θ) can be accurately calculated by Mie scattering theory. Based on this, the present applicant calculated the scattering light intensity i (D, θ) of one particle based on the scattering theory of the laser light irradiated onto the particle group to be measured and the particle size distribution nr (D). In between, T (D) − f i (D, θ)nr
Based on the fact that the following relationship (D)dD・ (1) holds, a particle size measuring device for determining the particle size distribution nr (D) was proposed.

The present invention has been made to apply the above device to the field of steam turbines, and is characterized by the following configuration. That is, in the present invention, a probe that can be inserted into a steam turbine is configured as follows at the tip of a cable consisting of an irradiation optical fiber and a plurality of light receiving optical fibers, and the irradiation optical fiber is attached to this probe. A laser beam is guided and irradiated onto the steam to be measured through the steam to be measured, and the scattered light at each scattering angle of the scattered light scattered by the steam to be measured is guided to the outside of the steam turbine through the light-receiving optical fiber, and the scattered light is roughly collected. A scattered light intensity distribution signal is obtained by receiving light, and a particle size distribution and a particle density are calculated from this scattered light intensity distribution signal. The probe adjusts the traveling direction of the laser light traveling within the irradiation optical fiber by 180 degrees.
a tip of the light irradiation fiber bent into a U-shape as if rotated; an optical system that shapes the light emitted from the tip of the irradiation optical fiber and irradiates the vapor to be measured; It is characterized by comprising the tip of the light-receiving optical fiber facing the system.

〔Effect of the invention〕

According to the present invention, since the particle size distribution and particle density of water droplets in a steam turbine can be accurately measured, the turbine efficiency and the erosion state of the rotor blades can be constantly and quantitatively monitored.

Moreover, according to this invention, only the probe needs to be inserted inside the steam turbine, which is in a high temperature and humid environment, and other equipment is installed outside the steam turbine and the two are connected using optical fibers. This allows for highly reliable monitoring. Moreover, with such a configuration, there are also effects such as extremely easy attachment and detachment to the steam turbine.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A steam monitoring device for a steam turbine according to an embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a steam turbine which is operated with wet steam and is to be used as a monitoring countercontamination. The steam monitoring Vi@ according to this embodiment includes a probe L whose tip is inserted into the steam turbine 1, a device main body 3-, and these probes L.
an irradiation optical fiber 4 and a plurality of light receiving optical fibers 51, 52, 53, which optically connect the device body Ω- to the irradiation optical fiber 4;
. . ., a cable connector consisting of 5n, and the device main body 1
Said probe, from? - an air pipe 7.8 for sending air to. Optical fiber for light reception 5
1 to 5n have a diameter of, for example, 100. It is desirable that the optical fiber be a large-diameter optical fiber with a diameter larger than that.

The main body of the device is connected to a probe via an optical fiber 4 for irradiation.
A laser light source 11 that supplies monochromatic laser light to 2-, a lens 12 that focuses the light from the laser light source 11 onto the input end of the irradiation optical fiber 4, and an output end of the light receiving light 1 fibers 51 to 5n. An interference filter 131 that transmits light of a specific wavelength to be subjected to measurement among the light emitted from the
, 132 , 13! , . . . , 13n, and a photodetector 14. which receives the light transmitted through these interference filters 131 to 13n and photoelectrically converts it. , 142 , 143,・
..., 14n, and these photodetectors 141 to 14
An amplifier 151゜15 that amplifies the output of n at a predetermined amplification factor.
2, 153,..., 15n and these amplifiers 15
an arithmetic device 16 that inputs the output signals from t to 15n and calculates the particle size distribution and particle density of water droplets of the steam to be measured;
A compressor 17 is connected to one end of the air pipe 7.8.

Further, the probe 2 is specifically constructed as shown in FIG. That is, numeral 21 in the figure is a fiber housing tube that collectively accommodates the tips of the irradiation optical fiber 4 and the light receiving optical fibers 51 to 5n. This fiber accommodation tube 21 has a hole 22 at its distal end through which the distal end of the irradiation optical fiber 4 can pass, and an opening 23 to be described later, and a support arm 24 extending toward the distal end side is provided in a protruding manner. It has become.

The distal end of the irradiation optical fiber 4 passes through the hole 22 and extends from the distal end of the optical fiber housing tube 21, is covered with a flexible light-shielding tube 25, and the distal end is rotated 180@. , the laser beam is transmitted to the opening 2 of the optical fiber housing tube 21.
The attachment is fixed to the support arm 24 via a plate 26 so that the light beam is emitted toward the support arm 24. A collimator lens 21 is provided at the tip of the irradiation optical fiber 4 for shaping the laser beam emitted therefrom into a parallel beam.

The collimator lens 21 and the tip of the irradiation optical fiber 4 are housed inside the cylinder 28. An annular member 29 is attached to the output end of the cylinder 28 . As shown in detail in FIG. 3, this annular member 29 is a hollow annular body 3 having a regular thickness on one side in the radial direction and a thin thickness on the other side.
An air ejection port 33 extending in the circumferential direction is formed on the inner surface of the hole 32 of No. 1 and at a portion located at the full thickness portion. Then, air A is introduced from the compressor 17 through an air pipe 7 connected to a thin wall portion of the outer peripheral surface of the hollow annular body 31, and the air A is jetted from the air jet port 33. The hole 32
It is possible to form an air curtain.

A cylindrical optical shield 34 is provided at a position facing the output end of the annular member 29 . This optical shield 34 is fixed to the support arm 24 via a support plate 35. The relative position between this optical shield 34 and the collimator lens 21 is such that the support plate 26.35 is
It can be adjusted by screws 36 and 37 that are fixed to. The optical shield 34 introduces light into the interior through an opening 38 on the proximal end side and outputs the light through an opening 39 on the forward m side. The diameter of the opening 39 is set to be slightly larger than the diameter of the laser beam emitted from the collimator lens 27. On the side of the optical shield 34,
An introduction hole 40 for introducing air is provided, and one end of the air vibe 8 is connected to this introduction hole 40.

The opening 23 of the optical fiber housing tube 21 faces the output end of the optical shield 34 via the measurement area P. This opening 23 is formed so that its width increases as it goes deeper, and the light-receiving ends of the light-receiving optical fibers 51 to 5n are placed inside the opening 23 at an equal distance from the measurement area P and at scattering angles O° and θ. Engineering, θ2. . . . is arranged at a position of θn-1. Their relative positions are determined by the support member 41. Note that the opening 23 of the optical fiber accommodation tube 21
The inner surface (portion Q surrounded by a dashed line in FIG. 2) is coated with black matte coating to prevent stray light.

Next, the operation of the steam monitoring device according to this embodiment configured as described above will be explained.

Monochromatic laser light generated by excavation of the laser light source 11 is guided into the irradiation optical fiber 4 via the lens 12,
A collimator lens 21 forms a parallel laser beam with a predetermined cross-sectional area. At this time, scattered light may be generated due to internal bubbles of the collimator lens 27, but most of this scattered light is blocked by the optical shield 34. Therefore, the measurement area P passes through the opening 39 of the optical shield 34.
Most of what is irradiated is the parallel beam component.

&Z'5T:,:]IJゝ-"I,i>:27(DU
The light exit end of the RWants@1 body 28, the opening 38, 39 of the optical shield 34, is in contact with the steam. Therefore, there is a possibility that water droplets in the steam may adhere to these parts and impede the progress of the laser beam. However, in the present embodiment, air A is sent from the compressor 17 into the inside of the annular member 29 and the optical shield 34, and an air curtain is formed around the annular member 29. Water droplets adhering to the holes 32 and openings 38 and 39 can be removed by blowing out air from inside.

When the laser beam C passes through such an air-purged optical system and irradiates the measurement area P, the laser beam C is scattered by the vapor R to be measured, and the scattered light C carrying the measurement information is scattered.
' is inputted into each of the light receiving optical fibers 51 to 5n.

The steam turbine 1 is connected to each light receiving optical fiber 51 to 5n.
Scattered light C' at each scattering angle guided to the outside passes through interference filters 131 to 13n to detectors 141 to
14n, the signal is photoelectrically converted, and further amplified by amplifiers 151 to 15n, and then input to the arithmetic unit 16 as a scattered light intensity distribution signal 1r (θ). The calculation device 16 calculates the particle size distribution nr (D>) from the input signal Ir (θ) by, for example, the logarithmic bound integral equation method or the logarithmic distribution function approximation method based on the above-mentioned (1).

By the way, since the scattered light intensity distribution signal 1r (θ) is a relative value, the particle size distribution nr (D) is also a relative value. Here, the particle size distribution nr (D) is expressed as f nr
(D) It is normalized so that dD=1 −17). Absolute particle size distribution n(D) and particle density Nth
can be calculated by the following method.

One method is to use the measured relative scattered light intensity distribution Ir
This is a method of converting (D) into a scattered light intensity distribution I(θ) expressed in terms of absolute intensity (light energy density W/end). That is, first, prior to measuring the vapor to be measured, a laser beam is irradiated onto a group of particles whose particle size distribution and particle density are known, and the scattered light intensity distribution 1 m (θ) is measured. On the other hand, the theoretical scattered light intensity distribution to (θ) by this particle group is calculated based on scattering theory, and is calculated as follows: K(θ)=Ip(θ)/Is(θ)...(3 calibration coefficient K( θ), the actual training value 1r
(θ), the absolute scattered light intensity distribution I(θ) can be determined using the following formula: I(θ)−K(θ)·[−r(θ) (4). Here, considering the attenuation of the incident light incident on the measurement area P, ■(θ) is expressed as
in exp (-XNOfc(D)nr(Dl
dD]・, /'i(D, θ)@π82N, nr(Dl
dDldX-(51). However, L: Scattered optical path length iin; Incident light intensity C(D): Scattered cross section B: Radius of the irradiation beam. value I
By substituting (θ) into the left side of Equation 51 and solving Equation 5 for No, the particle density N++ can be found. Therefore, n (D) −No −nr (D) ”
The absolute particle size distribution n(D) is also calculated using the equation (6).

Another method is to measure transmittance. That is, the measured transmittance E=■out(θ)/l1n(θ) is E==exp(-Lfc(DIN6ny(D)dDl
+・+ (Can be expressed as 71. Particle density can be found by solving equation (7) for No. The same applies below.

Through the above calculation, the calculation device 16 calculates the particle size distribution n(D)
Then, the particle density No. is calculated, and the result is sent to, for example, a display device or a control device (not shown).

In addition, the steam humidity H of the steam turbine is H=WI/W
b...Indicated by 181. Here, Wl: Weight of liquid in vapor Wb: Weight of total vapor. The pressure inside the turbine can be easily measured, and once the pressure is determined, the density of the gas and the density of the liquid can be determined from the saturated steam curve, and the weight Wb of the total steam can be determined. Since the particle size distribution n(D) is determined by the device of this embodiment, the number of particles of each particle size is known, and eventually the weight Wl of the gas in the steam is determined.

As described above, according to this embodiment, the particle size distribution and particle density of water droplets in the steam turbine 1 can be accurately measured, so that the turbine efficiency and the erosion state of the rotor blades can be constantly and quantitatively monitored. be able to. Moreover, in this case, only the probe 2- needs to be slightly inserted into the steam turbine 1 through one insertion port, and other equipment can be installed outside the steam turbine 1, so it is possible to install the probe 2- only slightly into the steam turbine 1, so that it is possible to install the probe 2- only slightly into the steam turbine 1 through one insertion port. It becomes possible to perform measurements under different environments. Also,
Since large-diameter fibers are used as the light-receiving optical fibers 51 to 5n, there is no need for a condensing lens, which contributes to miniaturization of the probe 2-.

Further, in this embodiment, the opening 2 of the optical fiber accommodation tube 21
The matte coating applied to 3, the optical shield 34, etc. can effectively eliminate the generation and influence of scattered light that becomes a noise component in measurement, and highly reliable monitoring can be performed. In addition, since air purge is applied to the exit port of the collimator lens 27 and the entrance and exit ports of the optical shield 34, the micro-diameter openings, etc. are blocked by water droplets in the steam, and the progress of light is disturbed. can be prevented.

In this way, according to this embodiment, extremely great effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of a steam measuring device for a steam turbine according to an embodiment of the present invention, FIG. 2 is a sectional view showing details of a probe in the device, and FIG. 3 is an annular member in FIG. 2. FIG. 3A is a perspective view, FIG. 1C is a cross-sectional view, and FIG. 1C is a front view. 1...Steam turbine 1. ? -...probe, L-...
- Equipment body, 4... Optical fiber for irradiation, 51 to 5n.
... Optical fiber for light reception, 6... Cable, 7, 8...
・Air pipe, 131~13n---Interference filter,
141-13n...detector, 21...optical fiber accommodation tube, 23...opening, 24...support arm, 25
...Light-shielding vibe, 26.35...Support plate, 27...
-Collimator lens, 29... annular member, 33...
Air outlet, 34... Optical shield, P... Measurement area.

Claims (5)

[Claims] (1) A laser light source installed outside the steam turbine,
An irradiation optical fiber is formed at its tip to be inserted into the steam turbine, and an irradiation optical fiber that guides the laser light from the laser light source into the steam turbine. a cable consisting of a plurality of light-receiving optical fibers that receive the scattered light guided by the steam to be measured and irradiated to the steam to be measured at each scattering angle and guide it to the outside of the steam turbine; a photodetector that receives the scattered light of each of the scattering tubes guided to the outside of the steam turbine through the photodetector and outputs the scattered light intensity distribution signal as a scattered light intensity distribution signal; and a scattered light intensity distribution signal output from the photodetector. and a calculation device for calculating the particle size distribution and particle density of the vapor to be measured from the irradiation optical fiber. an optical system that shapes the light emitted from the optical fiber for irradiation and irradiates it onto the vapor to be measured; and an optical system that faces the optical system for receiving light. A steam monitoring device for a steam turbine, characterized in that it is made of a tip of an optical fiber. (2) The optical system includes a collimator lens that shapes the laser beam emitted from the tip of the light irradiation fiber into a parallel beam, and an aperture that allows the light emitted from the collimator lens to pass through. A steam monitoring device for a steam turbine according to claim 1, characterized in that the device comprises a shielding body. (3) The steam turbine according to claim 2, wherein the collimator lens and the optical shield are supported by a mechanism that can adjust their relative positions. Steam monitoring equipment. (4) The optical system has an opening through which the laser beam passes and is in contact with the steam to be measured, and this opening is air-purged with air introduced from outside the steam turbine. A steam monitoring device for a steam turbine according to claim 1, characterized in that: (5) The steam monitoring device for a steam turbine according to claim 1, wherein at least a tip of the light-receiving optical fiber is covered with a member having a black matte surface.