CN114893258A - Steam film measuring and dehumidifying integrated system for last-stage stationary blade surface of steam turbine - Google Patents
Steam film measuring and dehumidifying integrated system for last-stage stationary blade surface of steam turbine Download PDFInfo
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- CN114893258A CN114893258A CN202210481220.5A CN202210481220A CN114893258A CN 114893258 A CN114893258 A CN 114893258A CN 202210481220 A CN202210481220 A CN 202210481220A CN 114893258 A CN114893258 A CN 114893258A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
- F01D21/003—Arrangements for testing or measuring
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
- F01D25/08—Cooling; Heating; Heat-insulation
- F01D25/10—Heating, e.g. warming-up before starting
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D9/00—Stators
- F01D9/02—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles
- F01D9/04—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles forming ring or sector
- F01D9/041—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles forming ring or sector using blades
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
Abstract
The invention provides a steam film measurement and dehumidification integrated system for the surface of a last-stage stationary blade of a steam turbine, which belongs to the technical field of dehumidification of the surface of the stationary blade of the steam turbine and comprises an ultrasonic detector, a signal processor, an instrument control terminal and a heating resistor. The steam film measuring and dehumidifying integrated system for the surface of the last-stage stationary blade of the steam turbine can control the thickness of the dry steam film in time, inhibit the formation of a water film on the surface of the blade, reduce the loss of wet steam, and improve the last-stage efficiency of the steam turbine and the overall safety of the steam turbine.
Description
Technical Field
The invention belongs to the technical field of surface dehumidification of a turbine stator blade, and particularly relates to a steam film measurement and dehumidification integrated system for a last-stage stator blade surface of a turbine.
Background
The last several grades of condensing steam turbine low pressure jar, nuclear power steam turbine all grades and marine nuclear power steam turbine all are in the wet steam district, and humidity increases and can lead to great wet steam loss, and the secondary water droplet that produces in addition condenses can strike the movable vane to destroy the blade. In all countries around the world, serious safety accidents are caused by the fracture of the turbine blades, so that the control of the flow of the wet steam on the surfaces of the blades has important significance on the economical efficiency and the safety of the operation of the turbine unit. In order to improve the stage efficiency of the wet steam stage and improve the safety of the steam turbine, researchers have proposed some control methods in the aspects of flowing working medium improvement, through-flow structure optimization, hollow stationary blade heating and the like. The well-covered hot steam film can improve the temperature of the surface of the blade, reduce the steam condensation on the surface of the blade, prevent water drops from depositing on the surface of the blade and inhibit the formation of a water film from the source; the reason is that with the same thermal steam film covering, water droplets of the main flow region reaching the blade surface must pass through the higher temperature thermal steam film, so that condensation of steam near the blade surface is further suppressed. Measuring and controlling the thickness of the dry steam film on the surface of the blade is a key factor for reducing the loss of the wet steam. There are many related methods how to measure the humidity of the wet steam and remove the water film: for example, humidity is measured acoustically, humidity is measured by conductivity, humidity is measured by the presence of a bluff body, and humidity is measured by ultrasound; in the aspect of dehumidification, a structure imitating diamond topology is used for enhancing dehumidification, a dehumidification structure is added for dehumidification, and hot steam dehumidification is also adopted. However, as for the steam turbine rotating at a high speed, there has been no sufficient study on how to systematically construct the measurement and the dehumidification in real time.
Disclosure of Invention
The invention aims to provide a steam film measuring and dehumidifying integrated system for the surface of a last-stage stationary blade of a steam turbine, which aims to realize the integration of steam film measuring and dehumidifying on the surface of the last-stage stationary blade of a low-pressure cylinder of the steam turbine, control the thickness of a dry steam film in time, inhibit the formation of a water film on the surface of a blade, reduce the loss of wet steam and improve the last-stage efficiency of the steam turbine and the overall safety of the steam turbine.
In order to achieve the purpose, the invention adopts the technical scheme that: the system comprises an ultrasonic detector, a signal processor, an instrument control terminal and a heating resistor, wherein the ultrasonic detector is arranged inside the suction side of the hollow stationary blade and is provided with a detection end which is flush with the surface of the hollow stationary blade and is suitable for detecting the thickness of a dry steam film on the surface of the hollow stationary blade; the signal processor is electrically connected with the signal output end of the ultrasonic detector and is used for receiving the signal detected by the ultrasonic detector and processing an interference signal; the instrument control terminal is electrically connected with the signal output end of the signal processor and used for receiving the signal processed by the signal processor; heating resistor locates hollow quiet leaf suction side inner wall and is suitable for heating hollow quiet leaf surface, with instrument control terminal signal output part electric connection, the instrument control terminal is according to dry vapor film thickness in order to control heating resistor's heating temperature.
In one possible implementation manner, the ultrasonic detectors are arranged in a plurality and are sequentially arranged at equal intervals along the blade height direction of the hollow stationary blade, and the plurality of ultrasonic detectors arranged along the blade height direction are defined as a group; and a plurality of groups are sequentially arranged at equal intervals along the axial chord length direction of the outlet of the hollow stationary blade.
In one possible implementation manner, the heating resistors are arranged in a plurality, are sequentially arranged at equal intervals along the blade height direction of the hollow stationary blade, and sequentially reduce the resistance value along the blade height direction, and the plurality of heating resistors arranged along the blade height direction are defined as a group; the hollow stationary blades are sequentially arranged in a plurality of groups at equal intervals along the flowing direction of the hollow stationary blades, and the resistance values are sequentially increased along the flowing direction.
In a possible implementation manner, the surface of the hollow stationary blade is provided with a threaded hole, the ultrasonic detector is provided with a columnar structure with an external thread on the outer circumference, the detection end is the outer end face of the columnar structure, the columnar structure is screwed in the threaded hole, and the detection end is flush with the surface of the hollow stationary blade.
In a possible implementation manner, the ultrasonic detector inside the hollow stationary blade is wrapped with a heat insulation layer, and the heat insulation layer is suitable for isolating heat generated by the heating resistor.
In a possible implementation manner, the heating temperature of the heating resistor is directly proportional to the thickness of the dry steam film, a threshold range of the thickness of the dry steam film is built in the instrument control terminal, and if the thickness of the dry steam film detected by the ultrasonic detector is not within the threshold range, the instrument control terminal controls the start and stop of the heating resistor, so that the thickness of the dry steam film is maintained within the threshold range or in a dynamic stable state.
In a possible realization mode, an insulating cover is connected to the inner wall of the hollow stationary blade, and the insulating cover is suitable for covering and buckling the heating resistor and isolating heat generated by the heating resistor.
In one possible implementation mode, the insulation cover comprises two layers of insulation layers, and the end parts of the two layers of insulation layers are connected to the inner wall of the hollow stationary blade and form vacuum between the two layers of insulation layers.
In one possible implementation mode, the bottom of the hollow stator blade is provided with a mounting hole, and the heating resistor penetrates into the inside of the hollow stator blade from the mounting hole and is attached to the inner wall of the hollow stator blade.
In one possible implementation, the hollow stationary blade has a plurality of threading holes at an end thereof, and the wire harnesses connecting the ultrasonic probe and the heating resistor are respectively passed through the plurality of threading holes.
The steam film measuring and dehumidifying integrated system for the surface of the last-stage stationary blade of the steam turbine has the advantages that: compared with the prior art, including ultrasonic detector, signal processor, instrument accuse terminal and heating resistor, detect the dry steam film thickness on the hollow quiet leaf through ultrasonic detector, and give signal transmission for signal processor, signal processor passes to instrument accuse terminal again after signal processing, instrument accuse terminal is through received signal, the heating temperature or the heating load of reasonable control heating resistor, make the dry steam film thickness maintain at dynamic stable state, can in time control the thickness of dry steam film, restrain blade surface water film formation, reduce the wet steam loss, improve steam turbine last stage efficiency and the whole security of steam turbine.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed for the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic structural diagram of an integrated system for measuring a steam film on a surface of a last stage stationary blade of a steam turbine and dehumidifying according to an embodiment of the present invention;
FIG. 2 is a flowchart of an ultrasonic detector of an integrated system for measuring a film on a last stage stationary blade surface and dehumidifying of a steam turbine according to an embodiment of the present invention;
FIG. 3 is a flow chart of a dry steam film measurement of an integrated system for measuring and dehumidifying a steam film on a last stage stationary blade surface of a steam turbine according to an embodiment of the present invention;
FIG. 4 is a cloud chart of the steam humidity distribution on the surface of a hollow stationary blade of the steam turbine final stage stationary blade surface steam film measurement and dehumidification integrated system according to the embodiment of the present invention;
fig. 5 is a schematic diagram of blade height distribution at the suction side of a hollow stationary blade of an integrated system for measuring a steam film on a surface of a last stage stationary blade of a steam turbine and dehumidifying according to an embodiment of the present invention (on the diagram, the bottom is a bottom end, the top is a top end, numbers indicate multiples of corresponding heights along a blade height direction, and dotted lines indicate positions at the corresponding heights);
fig. 6 is a schematic distribution diagram of ultrasonic detectors on hollow stationary blades of an integrated system for measuring a steam film and dehumidifying a surface of a last stage stationary blade of a steam turbine according to an embodiment of the present invention (a height direction on the diagram is a height direction of a hollow stationary blade, a horizontal direction is an axial chord length direction along an outlet of the hollow stationary blade, and a group is indicated by a dashed line);
FIG. 7 is a first ultrasonic detector model diagram of an integrated system for measuring and dehumidifying a film on a last stage stationary blade surface of a steam turbine according to an embodiment of the present invention;
FIG. 8 is a second model diagram of an ultrasonic detector of an integrated system for measuring a film on a last stage stationary blade surface and dehumidifying of a steam turbine according to an embodiment of the present invention;
FIG. 9 is a schematic structural diagram of an integrated system for measuring a film on a surface of a last stage stationary blade of a steam turbine and dehumidifying, in which an ultrasonic probe is mounted on a hollow stationary blade, according to an embodiment of the present invention;
fig. 10 is a schematic diagram of distribution of heating resistors on a hollow stationary blade of an integrated system for measuring a steam film and dehumidifying a surface of a last stage stationary blade of a steam turbine according to an embodiment of the present invention (where the size of a rectangular block represents a resistance value of the heating resistors, a height direction in the diagram is a height direction of the hollow stationary blade, a bottom end is a bottom of the hollow stationary blade, a top end is a top of the hollow stationary blade, a height direction of the blade is a direction from bottom to top, and a horizontal direction from left to right is a flow direction along the hollow stationary blade);
FIG. 11 is a cross-sectional view of a heating resistor installed inside a hollow stationary blade of an integrated system for measuring a steam film on a surface of a last stage stationary blade of a steam turbine and dehumidifying according to an embodiment of the present invention (in the figure, the bottom end is a surface of the hollow stationary blade, and the heating resistor and two layers of insulating layers are both located inside the hollow stationary blade);
FIG. 12 is a flowchart of an integrated system for measuring and dehumidifying a film on a last stage stationary blade surface of a steam turbine according to an embodiment of the present invention;
FIG. 13 is a schematic view of a threading hole structure of a steam film measuring and dehumidifying integrated system for a last stage stationary blade surface of a steam turbine, applied to a hollow stationary blade according to an embodiment of the present invention;
fig. 14 is a schematic structural view of a mounting hole of a steam turbine final stage stationary blade surface film measurement and dehumidification integrated system applied to a hollow stationary blade according to an embodiment of the present invention.
Description of reference numerals:
10. an ultrasonic detector; 11. a probe end; 12. a columnar structure; 13. a heat-insulating layer;
20. a signal processor;
30. an instrument control terminal;
40. a heating resistor;
50. a hollow stationary blade; 51. a threaded hole; 52. an insulating cover; 521. an insulating layer; 522. vacuum; 53. threading holes; 54. and (7) installing holes.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1 to 14, a system for measuring a film on a surface of a last stage stationary blade of a steam turbine and dehumidifying according to the present invention will be described. The steam film measuring and dehumidifying integrated system for the surface of the last-stage stationary blade of the steam turbine comprises an ultrasonic detector 10, a signal processor 20, an instrument control terminal 30 and a heating resistor 40, wherein the ultrasonic detector 10 is arranged inside the suction side of the hollow stationary blade 50 and is provided with a detection end 11 which is flush with the surface of the hollow stationary blade 50 and is suitable for detecting the thickness of a dry steam film on the surface of the hollow stationary blade 50; the signal processor 20 is electrically connected to the signal output end of the ultrasonic detector 10, and is configured to receive the signal detected by the ultrasonic detector 10 and process an interference signal; the instrument control terminal 30 is electrically connected with the signal output end of the signal processor 20 and is used for receiving the signal processed by the signal processor 20; the heating resistor 40 is arranged on the inner wall of the suction side of the hollow stationary blade 50, is suitable for heating the surface of the hollow stationary blade 50, and is electrically connected with the signal output end of the instrument control terminal 30, and the instrument control terminal 30 controls the heating temperature of the heating resistor 40 according to the thickness of the dry steam film.
Compared with the prior art, the steam film measurement and dehumidification integrated system for the surface of the last-stage stationary blade of the steam turbine comprises an ultrasonic detector 10, a signal processor 20, an instrument control terminal 30 and a heating resistor 40, wherein the thickness of a dry steam film on a hollow stationary blade 50 is detected through the ultrasonic detector 10, a signal is transmitted to the signal processor 20, the signal processor 20 processes the signal and then transmits the signal to the instrument control terminal 30, and the instrument control terminal 30 reasonably controls the heating temperature or the heating quantity of the heating resistor 40 through the received signal to maintain the thickness of the dry steam film in a dynamic stable state, so that the thickness of the dry steam film can be controlled in time, the formation of a water film on the surface of the blade is inhibited, the loss of wet steam is reduced, and the last-stage efficiency of the steam turbine and the overall safety of the steam turbine are improved.
The invention is particularly suitable for measuring the steam film on the surface of the stationary blade of the steam turbine in operation, because the internal space of the hollow stationary blade 50 is limited, and other structural parts are not convenient to place to fix the ultrasonic detector 10, so the technical problem that the ultrasonic detector 10 cannot be fixed in the hollow stationary blade 50 can be solved through the invention, and the technical problem that the thickness of the dry steam film cannot be measured on line in real time on the steam turbine in (high-speed) operation can also be solved.
The instrument control terminal 30 is provided with a control module for adjusting current, and the heating temperature is adjusted by adjusting the heating current of the heating resistor 40, so that the heating amount of the heating resistor 40 on the surface of the hollow stationary blade 50 is changed, and real-time adjustment is realized. The thickness of the dry steam film is measured, and the dry steam film is properly heated and dehumidified, so that the impact and damage of secondary water drops to the moving blade are greatly reduced, and the safety of the steam turbine is improved.
In some embodiments, referring to fig. 5 to 6, the plurality of ultrasonic probes 10 are arranged in series at equal intervals along the blade height direction of the hollow stationary blade 50, and a group of the plurality of ultrasonic probes 10 arranged along the blade height direction is defined; a plurality of groups are sequentially arranged at equal intervals along the axial chord length direction of the outlet of the hollow stationary blade 50. Because of the location of the main measured thickness at the dry steam film thickness on the suction side of the hollow vane 50, the plurality of ultrasonic probes 10 are evenly distributed on the suction side.
On the suction side of the hollow vane 50, the humidity is greater than that on the pressure side, and therefore, controlling the vapor film thickness on the suction side allows control of moisture loss caused by liquid droplets and reduction of related safety accidents. Since the surface humidity of the vane is decreased from the bottom to the top when the surface humidity changes, the ultrasonic probe 10 is provided only between 0 and 0.5 times the blade height of the hollow vane 50. Ultrasonic detectors 10 are arranged at the blade height positions of 0.1, 0.2, 0.3, 0.4 and 0.5, the total number of the ultrasonic detectors is 5, 3 groups are arranged at the axial chord length close to the outlet of the hollow static blade 50, the ultrasonic detectors are arranged at the positions 5%, 15% and 25% away from the outlet of the hollow static blade 50, and finally, 15 ultrasonic detectors 10 are arranged in total to measure the thickness of the dry steam film on the surface of the hollow static blade 50.
In some embodiments, referring to fig. 10, the plurality of heating resistors 40 are arranged in the blade height direction of the hollow stationary blade 50 at equal intervals in sequence, and the resistance values decrease in sequence in the blade height direction, defining the plurality of heating resistors 40 arranged in the blade height direction as a group; plural sets are sequentially provided at equal intervals in the flow direction of the hollow stationary blades 50, and the resistance values sequentially increase in the flow direction. The above flow direction is a flow direction of the steam film on the hollow stationary blade 50 during the operation of the steam turbine. Through the arrangement mode, the suction side of the hollow stationary blade 50 can be uniformly heated, and the effect of uniformly controlling the thickness of the dry steam film is achieved.
In fig. 11, the size of the resistance value is represented by the size of a rectangular solid, and the resistance value decreases in the suction side in the vane interior in the blade height direction; along the flow direction, the resistance value increases in order.
In some embodiments, referring to fig. 7 to 9, the surface of the hollow stationary blade 50 has a threaded hole 51, the ultrasonic probe 10 has a cylindrical structure 12 with an external thread on the outer circumference, the probe end 11 is the outer end surface of the cylindrical structure 12, the cylindrical structure 12 is screwed into the threaded hole 51, and the probe end 11 is flush with the surface of the hollow stationary blade 50. The ultrasonic probe 10 is placed inside the hollow stationary blade 50, and the columnar structure 12 is connected in the threaded hole 51, so that the ultrasonic probe 10 and the hollow stationary blade 50 are connected. The threaded hole 51 is a threaded hole 51 that has been previously drilled with a threaded hole 51 tool. And the columnar structure 12 is a part of the structure on the ultrasonic probe 10.
Preferably, the probing end 11 is a smooth wall surface, and when the external thread on the columnar structure 12 is screwed into the threaded hole 51, the plane of the probing end 11 is on the plane of the surface of the hollow stationary blade 50, that is, the two are coplanar. This enables the dry steam film thickness at the probe end 11 to be detected by the ultrasonic probe 10, and thus, the dry steam film thickness on the surface of the hollow stationary blade 50 can be determined.
In order to prevent the heat generated by the heating resistor 40 from affecting the ultrasonic probe 10, in some embodiments, referring to fig. 8, the ultrasonic probe 10 inside the hollow stationary blade 50 is wrapped with an insulating layer 13, and the insulating layer 13 is adapted to insulate the heat generated by the heating resistor 40. The heat-insulating layer 13 is made of a heat-insulating material, and the specific material is not limited in the present invention, and may be one layer or a plurality of layers, which can perform a heat-insulating function and effect on the ultrasonic detector 10.
Specifically, the heat insulating layer 13 may be a heat insulating sleeve or a heat insulating sleeve, so as to achieve heat insulating and heat preserving effects, and prevent heat from being transferred to the ultrasonic detector 10.
In some embodiments, referring to fig. 1-3 and 12, the heating temperature of the heating resistor 40 is proportional to the thickness of the dry vapor film, a threshold range of the thickness of the dry vapor film is built in the instrumentation and control terminal 30, and if the thickness of the dry vapor film detected by the ultrasonic detector 10 is not within the threshold range, the instrumentation and control terminal 30 controls the start and stop of the heating resistor 40, so as to maintain the thickness of the dry vapor film within the threshold range or in a dynamic stable state. The threshold range is set on the instrument control terminal 30 in advance, and the threshold range can be adjusted reasonably manually according to the control range of the dry steam film on the last-stage stationary blade of the low-pressure cylinder of the steam turbine, so that the dry steam film is maintained in a dynamic stable state all the time.
In order to prevent the heat generated by the heating resistor 40 from being transferred to the outside and to transmit the heat to the surface of the hollow stationary blade 50 to the maximum, in some embodiments, referring to fig. 11, an insulating cover 52 is connected to the inner wall of the hollow stationary blade 50, and the insulating cover 52 is adapted to cover the heating resistor 40 and to isolate the heat generated by the heating resistor 40. The insulating cover 52 may be in various forms, and it is sufficient to surround the heating resistor 40 and to easily mount the heating resistor 40.
To enhance the thermal isolation of the insulating shroud 52, in some embodiments, referring to FIG. 11, the insulating shroud 52 includes two layers of insulating layers 521, the ends of the two layers of insulating layers 521 are connected to the inner wall of the hollow vane 50 and a vacuum 522 is formed therebetween. The insulating layer 521 is made of insulating materials, and vacuum 522 is arranged between the two insulating layers 521, so that the heat insulation effect is further enhanced. The insulating layer 521 positioned outside covers and buckles the insulating layer 521 positioned inside, the space between the two layers is closed, a through hole is formed in the insulating layer 521 positioned outside, a pipeline connected through vacuum pumping equipment penetrates through the through hole and is inserted into the closed space, the space is vacuumized, and finally the through hole is sealed by a sealing piece.
In order to improve the installation convenience of the heating resistor 40, in some embodiments, referring to fig. 14, the bottom of the hollow stationary blade 50 has a mounting hole 54, and the heating resistor 40 penetrates into the hollow stationary blade 50 from the mounting hole 54 and is attached to the inner wall of the hollow stationary blade 50. The heating resistor 40 is easy to install, the heating resistor 40 is connected with a connecting piece, and the inner wall of the hollow stationary blade 50 is provided with a groove, a clamping groove, a boss and other structures which are in adaptive connection with the connecting piece, so that the connecting piece is connected with the inner wall of the hollow stationary blade 50. The connecting piece can be a thread gluing, a buckle and the like. In addition, the connecting member may not be provided, and the heating resistor 40 may be directly inserted into the mounting hole 54 and placed in a space surrounded by the insulating cover 52 and the inner wall of the hollow stationary blade 50, so as to also have an effect of heating the surface of the hollow stationary blade 50. In addition, the connecting member can pass through the mounting hole 54, and the heating resistor 40 is in a strip shape and can be conveniently installed in the mounting hole 54.
Preferably, the mounting hole 54 is located on the wall surface of the hollow stationary blade 50 covered by the insulating cover 52, and the heating resistor 40 is inserted through the mounting hole 54 and attached to the inner wall of the hollow stationary blade 50, and is also located within the range covered by the insulating cover 52, so as to facilitate the mounting of the heating resistor 40 and to insulate the insulating cover 52.
In some embodiments, referring to fig. 13, the hollow stationary blade 50 has a plurality of threading holes 53 at its end, and the wire harness connecting the ultrasonic probe 10 and the heating resistor 40 is passed through the plurality of threading holes 53, respectively. The number of the threading holes 53 is two, and two wire harnesses can be threaded through the threading holes, so that the electrical connection between the components of the present invention can be realized. The structure shown in fig. 13 does not represent the hollow vane 50 but is a model.
The ultrasonic detector 10 transmits signals to the signal processor 20 for screening processing, then useful signals are transmitted to the instrument control terminal 30, the instrument control terminal 30 calculates and processes the signals, a heating instruction is transmitted, the heating resistor 40 heats the suction side of the hollow stationary blade 50, and dynamic adjustment is achieved.
The principle of the ultrasonic detector 10 for detecting the thickness of the dry steam film is as follows: the transmitter on the ultrasonic detector 10 transmits ultrasonic waves in the direction perpendicular to the surface of the blade, timing is started while the ultrasonic waves are transmitted, the ultrasonic waves are transmitted in water vapor and return immediately when meeting water drops in the process, and the receiver of the ultrasonic detector 10 stops timing immediately after receiving the reflected waves, so that the thickness of the dry vapor film is calculated according to the principle. Thickness is the speed of sound time, where the speed of sound is the speed of the ultrasound in the dry vapor film and the time is half the time from the emission of the ultrasound to the receipt of the reflected sound wave. The instrument control terminal 30 starts the ultrasonic detector 10 and emits ultrasonic waves, and simultaneously starts a timer to transmit the ultrasonic waves to the dry steam film to be measured, the ultrasonic waves return when meeting liquid drops, reflected sound waves are received, the stop time of the timer is determined by detecting the reflected sound waves, and the time is transmitted to the signal processor 20. The time required for the ultrasonic wave to hit the surface of the liquid drop after being transmitted and then reflected to the receiver of the ultrasonic probe 10 is first obtained, a large amount of data on the time is obtained through a large number of measurements in a short time, the time data is summarized, the number of figures is selected as real data, and the time is transmitted to the signal processor 20.
The signal processor 20 operates on the principle of: the signals conducted from the ultrasound probe 10 need to be processed for use; generally, the thickness measurement (ultrasonic thickness measurement) of the dry vapor film by the ultrasonic detector 10 can be performed only at normal temperature, and cannot be satisfied at high temperature. When the temperature is higher than 60 ℃, the ultrasonic thickness measurement has errors caused by the temperature, and the measurement value is generally larger. Therefore, error correction is required, and signal collection and processing are performed by the signal processor 20, and the actually collected signals are processed into useful accurate information and then transmitted to the instrument control terminal 30. The signal processor 20 mainly processes the influence of temperature on the ultrasonic waves, establishes a sound velocity and temperature database in advance, and finds out the corresponding speed by using the transmitted temperature and time, and calculates the thickness of the dry steam film.
The operating principle of the instrument control terminal 30 is as follows: the instrument control terminal 30 processes the signal transmitted by the signal processor 20, displays the thickness percentage of the current dry steam film in real time (namely, a display is arranged on the instrument control terminal 30), and adjusts and controls the current of the heating resistor 40 according to the percentage of the thickness of the steam film in the gaps between the blades, thereby achieving the purpose of adjusting the heating quantity.
The working principle of the heating resistor 40 is as follows: in the prior art, the interior of the hollow stationary blade 50 is generally heated by introducing hot steam, but the reaction time of heating by adopting steam is long, and the quantity cannot be accurately controlled, so that resistance is adopted for heating. The heating resistor 40 may be a resistor row, and generates heat after being electrified and heats the wall surface of the hollow stationary blade 50, thereby achieving the purpose of controlling the thickness of the dry steam film on the surface of the stationary blade. The instrument control terminal 30 regulates and controls the current, changes the wall surface temperature of the hollow stationary blade 50 and plays a role in heating wall surface water vapor; the larger the heating amount is, the higher the wall surface temperature is, and finally the thickness of the steam film can be increased. When the thickness measured by the ultrasonic detector 10 reaches a required value (i.e., a threshold range), the thickness is fed back to the instrument control terminal 30 for negative feedback adjustment, and finally dynamic stability is achieved.
The invention uses the ultrasonic detector 10 to detect the thickness of the dry steam film, and uses the thickness as an evaluation index, and can scientifically and reasonably evaluate the dehumidification effect; the signal processor 20 can process the interference signals transmitted by the detector, correct the useful signals to eliminate the influence of high temperature on the signals, and finally transmit accurate signals to the instrument control terminal 30; the instrument control terminal 30 can directly control the current of the heating resistor 40, thereby controlling the heating amount of the heating resistor 40 on the surface of the hollow stationary blade 50, and manually setting various grade standards so as to achieve corresponding targets and requirements. The four devices form a system, and the thickness of a dry steam film can be controlled in time, so that the formation of the water film on the surface of the hollow stationary blade 50 is inhibited, the wet steam loss is reduced, and the final stage efficiency of the steam turbine and the overall safety of the steam turbine are improved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. The utility model provides a steam turbine last stage quiet leaf surface vapor film measurement and dehumidification integration system which characterized in that includes:
the ultrasonic detector is arranged inside the suction side of the hollow stationary blade and is provided with a detection end which is flush with the surface of the hollow stationary blade and is suitable for detecting the thickness of the dry steam film on the surface of the hollow stationary blade;
the signal processor is electrically connected with the signal output end of the ultrasonic detector and is used for receiving the signal detected by the ultrasonic detector and processing an interference signal;
the instrument control terminal is electrically connected with the signal output end of the signal processor and is used for receiving the signal processed by the signal processor; and
heating resistor locates hollow quiet leaf suction side inner wall and is suitable for heating hollow quiet leaf surface, with instrument control terminal signal output part electric connection, the instrument control terminal is according to dry vapor film thickness in order to control heating resistor's heating temperature.
2. The integrated system for measuring and dehumidifying a steam film on a surface of a last-stage stationary blade of a steam turbine according to claim 1, wherein the plurality of ultrasonic detectors are arranged in series at equal intervals along a blade height direction of the hollow stationary blade, and a plurality of ultrasonic detectors arranged along the blade height direction are defined as a group; and a plurality of groups are sequentially arranged at equal intervals along the axial chord length direction of the outlet of the hollow stationary blade.
3. The integrated system for measuring and dehumidifying the steam film on the surface of the last-stage stationary blade of the steam turbine as claimed in claim 1, wherein said heating resistors are provided in plurality, are arranged at equal intervals in sequence in the blade height direction of the hollow stationary blade, and are sequentially decreased in resistance value in the blade height direction, and define a plurality of said heating resistors arranged in the blade height direction as a group; the hollow stationary blades are sequentially arranged in a plurality of groups at equal intervals along the flowing direction of the hollow stationary blades, and the resistance values are sequentially increased along the flowing direction.
4. The integrated system for measuring and dehumidifying a steam film on a surface of a last stage stationary blade of a steam turbine according to claim 1, wherein the surface of the hollow stationary blade has a threaded hole, the ultrasonic probe has a cylindrical structure with an external thread on an outer circumference, the probe end is an outer end face of the cylindrical structure, the cylindrical structure is screwed in the threaded hole, and the probe end is flush with the surface of the hollow stationary blade.
5. The integrated system for measuring and dehumidifying a steam film on a surface of a last stage stationary blade of a steam turbine according to claim 1, wherein the ultrasonic probe located inside the hollow stationary blade is covered with an insulating layer adapted to insulate heat generated by the heating resistor.
6. The integrated system for measuring and dehumidifying a steam film on a surface of a last stage stationary blade of a steam turbine according to claim 1, wherein a heating temperature of the heating resistor is proportional to a thickness of the dry steam film, the control terminal is provided with a threshold range of the thickness of the dry steam film, and if the thickness of the dry steam film detected by the ultrasonic detector is not within the threshold range, the control terminal controls the heating resistor to be started and stopped so as to maintain the thickness of the dry steam film within the threshold range or in a dynamic stable state.
7. The integrated system for steam film measurement and dehumidification of the surface of the last stage stationary blade of the steam turbine as claimed in claim 1, wherein an insulating cover is attached to the inner wall of the hollow stationary blade, said insulating cover being adapted to cover said heating resistor and to insulate the heat generated by said heating resistor.
8. The integrated system for vapor film measurement and dehumidification of a last stage vane surface of a steam turbine of claim 7, wherein said insulation shroud comprises two layers of insulation, each of said two layers of insulation being attached to an inner wall of a hollow vane and forming a vacuum therebetween.
9. The integrated system for measuring and dehumidifying a steam film on a surface of a last stage stationary blade of a steam turbine according to claim 1, wherein the bottom of the hollow stationary blade has a mounting hole, and the heating resistor penetrates into the inside of the hollow stationary blade from the mounting hole and is attached to an inner wall of the hollow stationary blade.
10. The integrated system for measuring and dehumidifying a steam film on a surface of a last stage stationary blade of a steam turbine according to claim 1, wherein the hollow stationary blade end portion has a plurality of threading holes, and a wire harness for connecting the ultrasonic probe and the heating resistor is passed through the plurality of threading holes, respectively.
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