JP2009250110A - Deterioration detection system of expansion joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system capable of easily and safely detecting the deterioration, in an expansion joint interposed in a metallic duct connected to combustion equipment such as a gas turbine and an incinerator. <P>SOLUTION: This deterioration detection system has the expansion joint 8A having at least two layers of flexible seal films 15 and 16 airtightly connected to a joint of the metallic duct 5 connected to the combustion equipment, a first differential pressure detecting part 30 for detecting differential pressure between pressure between the flexible seal films 15 and 16 of the two layers and pressure inside of the expansion joint 8A, and a second differential pressure detecting part 31 for detecting differential pressure between the pressure between the flexible seal films 15 and 16 of the two layers and pressure outside of the expansion joint 8A. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a system for detecting deterioration of an expansion joint connected to a duct of a combustion apparatus such as a gas turbine or a garbage incinerator.

  In stationary gas turbines for power generation and machine driving, combustion air supplied through an intake duct is compressed by a compressor, mixed with fuel and burned, and turbine blades are rotated by generated high-temperature and high-pressure gas to generate power. obtain. Combustion gas is discharged from the exhaust duct as exhaust gas.

  The combustion air supplied to the gas turbine is taken in the gas turbine through the metal intake duct after dust and corrosive components contained in the outside air are removed by an intake filter that cleans the combustion air. The gas turbine main body expands and contracts due to operation and stoppage, and therefore, a deviation occurs between the gas turbine body and the intake duct. In order to absorb this deviation, an expansion joint is interposed in the intake duct. In general, expansion joints for intake ducts are used at room temperature, the internal fluid is clean, the internal pressure is about minus 1 kPa of atmospheric pressure, and airtightness with the outside is necessary, etc. A rubber film having elastic flexibility is employed.

  When the expansion joint of the intake duct is torn during gas turbine operation (when an opening is made), the following problems (1) to (4) occur due to direct intake of outside air.

  (1) Dust in the outside air is sucked in, and dust adheres to the moving and stationary blades of the air compressor of the gas turbine, reducing the compression efficiency and reducing the efficiency of the gas turbine.

  (2) When corrosive components such as sulfur, potassium, sodium, and chlorine are contained in the dust in the outside air, high-temperature sulfidation corrosion and stress corrosion cracking occur in the turbine rotor and stator blades.

  (3) The air cleaned by the intake filter is then rectified while passing through the air duct and flows into the air compressor of the gas turbine. However, if the expansion joint is lost, this rectification is inhibited and drifts at the air compressor inlet. If turbulent flow or vortex flow is generated and resonates with the natural frequency of the moving and stationary blades of the air compressor, it will lead to a blade breakage accident.

  (4) If the expansion joint is installed inside the enclosure, it is necessary to open the door for daily inspections, and the internal inspection must be performed. There is a risk of accidents such as burns when touching a part.

  Next, regarding the exhaust duct, since the exhaust gas discharged from the gas turbine has a high temperature exceeding 500 ° C., the exhaust gas is often supplied to the exhaust gas boiler through the exhaust duct and recovered. Because the exhaust gas discharged from the gas turbine is hot, the metal exhaust duct connecting the gas turbine and the downstream equipment (exhaust heat recovery exhaust gas boiler, etc.) absorbs the thermal expansion and contraction of the duct. Expansion joints are interposed (Patent Document 1, etc.). If the expansion joint of the exhaust duct of the gas turbine is broken, high-temperature exhaust gas is released, which is dangerous.

  Further, exhaust gas discharged from a garbage incinerator, boiler, or the like becomes high in temperature, and it is dangerous if the expansion joints interposed in the exhaust ducts of these combustion apparatuses are broken.

Conventionally, a monitoring function for detecting deterioration such as breakage of an expansion joint has not been provided, and daily visual inspection is performed to predict and replace the deterioration life.
Japanese Patent No. 3790403

  However, the visual inspection as described above takes time, and there is a risk that the inspection work may be dangerous.

  Then, this invention aims at providing the system which can detect deterioration easily and safely about the expansion joint interposed in metal ducts connected to combustion apparatuses, such as a gas turbine and an incinerator. To do.

  In order to achieve the above object, an expansion joint deterioration detection system according to the present invention includes an expansion joint having at least two flexible sealing films hermetically connected to a seam of a metallic duct connected to a combustion device. A pressure detecting means for detecting a pressure between at least the two layers of the flexible seal films, in order to detect deterioration of at least one of the two layers of the flexible seal films; It is characterized by having.

  The pressure detecting means includes a first differential pressure detecting unit for detecting a differential pressure between the pressure between the two layers of flexible seal films and the pressure inside the expansion joint, and the two layers of flexible It is good also as having a 2nd differential pressure | voltage detection part for detecting the differential pressure | voltage between the pressure between adhesive seal membranes, and the pressure outside the said expansion joint.

  The combustion device is a gas turbine, and the expansion joint is disposed in an enclosure that is connected to an intake duct of the gas turbine and accommodates the gas turbine, in which a ventilation fan is installed, and the first differential pressure detection unit Detects the differential pressure between the combustion air pressure in the expansion joint and the pressure between the two layers of flexible seal membranes, and the second differential pressure detector is enclosed by the enclosure outside the expansion joint. It is also possible to detect a differential pressure between the ambient atmospheric pressure and the pressure between the two layers of flexible sealing films.

  In the present invention, the expansion joint has at least two layers of flexible seal membranes, and the two-layer flexible seal membranes seal the duct seams. The pressure between the two layers of the flexible seal membrane, the pressure inside the expansion joint (pressure inside the duct) and the pressure outside the expansion joint (pressure outside the duct) are before and after the flexible seal membrane is broken. If they are different, it is possible to detect the breakage of the flexible sealing film by monitoring these pressure changes.

  Further, even if one of the two layers of the flexible sealing film is broken, the airtightness in the expansion joint and the duct can be secured by the other flexible sealing film.

  In the gas turbine, a large amount of air flows in the intake duct during the operation of the gas turbine, and the pressure is reduced from the normal pressure by suction by the compressor. In addition, a ventilation fan is attached to the enclosure in which the gas turbine is housed. Depending on the ventilation method of the ventilation fan, the enclosure is in a reduced pressure state or pressurized state compared to normal pressure during the operation of the ventilation fan. It becomes a state. Therefore, when the expansion joint of the intake duct is disposed in the enclosure, if normal pressure air is sealed between the two layers of flexible seal membranes, the space between the two layers of flexible seal membranes is reduced. A pressure difference is generated between the pressure and the pressure inside and outside the expansion joint, and by detecting these pressure differences, it is possible to detect that the flexible seal film has been torn if the pressure difference becomes zero.

  An embodiment of a deterioration detection system for an expansion joint according to the present invention will be described below with reference to FIGS. In addition, the same code | symbol was attached | subjected about the same component through all the drawings and all the embodiments.

  FIG. 1 is a conceptual diagram showing a schematic configuration of a gas turbine generator. The gas turbine 1 is housed in the enclosure 4 together with the generator 2 and the speed reducer 3. An air intake duct 5 is inserted into the enclosure 4, and a ventilation fan 6 is attached to the enclosure 4. A ventilation duct 7 is connected to the ventilation fan 6. The intake duct 5 is connected to the compressor 9 of the gas turbine 1 through the expansion joint 8A, and supplies the combustion air obtained by filtering dust and the like with the intake filter 5a to the compressor 9. The combustion air compressed by the compressor 9 is mixed with fuel and burned by the combustor 10 to become high-temperature and high-pressure gas, and drives the turbine 11. The generator 2 is driven through the speed reducer 3 connected to the turbine 11 and the compressor 9 to generate electricity. Exhaust gas discharged from the turbine 11 is discharged from the exhaust duct 12. An expansion joint 8B is interposed in the exhaust duct. Both the intake duct 5 and the exhaust duct 12 are made of metal.

  FIG. 2 is an enlarged cross-sectional view of the expansion joint 8 </ b> A interposed in the intake duct 5. As shown in FIG. 2, two layers of flexible sealing films 15 and 16 are provided. The flexible sealing films 15 and 16 have a cylindrical shape. The flexible sealing films 15 and 16 are formed on the plate 20 with flanges 17 and 18 fixed to the connected end portions 5a and 5b near the joint of the suction duct 5 with spacers 19 interposed between both ends. The bolts and nuts 21 are fastened and fixed. A sealed space M is formed between the flexible sealing films 15 and 16 by the spacers 19 and 19 sandwiched between both ends of the flexible sealing films 15 and 16. The fixing method of the flexible seal films 15 and 16 to the suction duct 5 is not limited to the fixing structure in the illustrated example, and various fixing structures can be adopted.

  Since the combustion air flowing inside the suction duct 5 is at room temperature, the flexible sealing film is a rubber having elastic flexibility such as neoprene rubber, fluorine rubber, silicon rubber, urethane rubber, nitrile rubber, butyl rubber, etc. It can be made of a material and may be reinforced with fibers. The spacer 19 may also be formed of the same material as that of the flexible sealing film, or may be formed of other materials as long as the sealing property between the flexible sealing films can be ensured. Although not shown, the spacer 19 in FIG. 2 may be omitted, and the two cylindrical flexible sealing films may be bonded only at the peripheral part to make the space between the flexible sealing films except the peripheral part airtight. Alternatively, as shown in FIG. 3, the two layers of flexible sealing films 15 and 16 may be formed by integral molding together with the peripheral portion 19A.

When the gas turbine 1 is operating, the combustion air A is sucked into the compressor 9 through the intake duct 5. Therefore, the pressure Pin _in the intake duct 5 is in a depressurized state of about minus 1 kPa compared to the normal pressure (atmospheric pressure). Further, when the gas turbine 1 is operating, for ventilating the enclosure 4 by the ventilation fan 6, depending on the ventilation system, the pressure P _out of the enclosure 4 is depressurized or pressurized state compared to normal pressure . If the space M between the flexible seal films 15 and 16 of the expansion joint 8A is filled with atmospheric pressure air, the pressure P _M between the flexible seal films 15 and 16 and the inside of the expansion joint 8A flow. pressure difference is generated between the pressure P _in the combustion air a. In addition, a pressure difference is generated between the pressure P _M between the flexible sealing films 15 and 16 and the air pressure P _{out of} the expansion joint 8A (atmosphere pressure surrounded by the enclosure 4) P _out .

As pressure detecting means, a first differential pressure detecting portion 30 for detecting the differential pressure dP ₁ of the inner pressure _{P in} the pressure _{P M} and expansion joints 8A of M between the flexible seal membranes 15 and 16, A second differential pressure detector 31 for detecting a differential pressure dP ₂ between the pressure P _M between the flexible sealing films 15 and 16 and the pressure P _out outside the expansion joint 8A is provided.

The first differential pressure detector 30 detects a differential pressure dP ₁ between the measured pressure of the pressure sensor 30a and the measured pressure of the pressure sensor 30b, and the second differential pressure detector 31 detects the measured pressure of the pressure sensor 31a and the pressure sensor. detecting the differential pressure dP ₂ and 31b of the measurement pressure. The detection of the differential pressure can be performed by a known arithmetic circuit. In the illustrated example, the pressure sensors 30a and 31a are separate sensors, but a circuit configuration may also be used with a single pressure sensor. As the pressure sensor, a known pressure sensor can be used. For example, a pressure sensor incorporating a piezoelectric element can be used.

Further, the first differential pressure detection unit 30 and the second differential pressure detection unit 31 use the differential pressures dP ₁ and dP ₂ as differential pressure signals to control power equipment such as a DCS (Distributed Control System) (see FIG. (Not shown)). DCS is a well-known system that performs distributed control of power equipment such as a gas turbine, a generator, a boiler, and incidental equipment.

These differential pressures dP ₁ and dP ₂ are constantly monitored by the first differential pressure detection unit 30 and the second differential pressure detection unit 31, and if these differential pressures become zero during operation of the gas turbine, Either one of the flexible sealing film 15 and the outer flexible sealing film 16 starts to be broken, and it is determined that the deterioration has started, and DCS automatically generates an alarm. It should be noted that the space M between the flexible seal films 15 and 16 is reduced to a predetermined pressure or lower, or an inert gas is injected so that the pressure is different from the pressure inside and outside the expansion joint 8A. It can also be set as the pressurization state more than predetermined pressure.

  As described above, since it is possible to automatically detect that one of the flexible sealing films 15 and 16 constituting the expansion joint 8A has started to be broken, it is safer and quicker than the visual inspection. Deterioration can be detected.

By monitoring the differential pressures dP ₁ and dP ₂ by both the first differential pressure detector 30 and the second differential pressure detector 31, the inner flexible seal film 15 and the outer flexible film 15 Since it is possible to determine which of the sealing films 16 has been damaged, only the damaged flexible seal can be replaced.

  Even if one of the flexible sealing films 15 and 16 is broken, the other flexible sealing film can secure the airtightness in the expansion joint 8A. The gas turbine can be continuously operated until the flexible sealing film is replaced with a new expansion joint.

  Further, the expansion joint 8A interposed in the intake duct 5 can prevent the external air that has not been filtered from being mixed into the combustion air by quickly detecting the deterioration. It is possible to prevent deterioration, high-temperature sulfidation corrosion and stress corrosion cracking of the gas turbine rotor and stator blades, and damage accidents due to resonance of the compressor rotor and stator blades.

  When the expansion joint 8A is disposed outside the enclosure 4, as described above, the M between the flexible seal films 15 and 16 is brought into a reduced pressure state below a predetermined pressure, or is inactive. It is only necessary to press the gas into a pressurized state that is equal to or higher than a predetermined pressure.

FIG. 4 is a cross-sectional view showing an expansion joint deterioration detection system according to another embodiment. In this embodiment, only the pressure sensor 40 that monitors the pressure P _M between the two layers of flexible sealing films 15 and 16 is provided as the pressure detection means. _Assuming that the pressure PM before any of the flexible sealing films 15 and 16 breaks is normal pressure, either one of the two layers of flexible sealing films 15 and 16 is in operation during the operation of the gas turbine 1. When broken, the pressure between the flexible seal membranes 15 and 16, the _{P M,} so changes to the outside of ambient pressure _{P out} of the inner pressure _{P in} or expansion joint expansion joints 8A, the two-layer flexible It can be detected that any of the sealing films 15 and 16 starts to break. In this case, which of the two layers of the flexible sealing films 15 and 16 is broken can be determined based on whether the measurement value of the pressure detecting means is P _in or P _out . In this example as well, the M between the flexible seal films 15 and 16 is reduced to a predetermined pressure or lower as necessary, or an inert gas is injected to increase the pressure to a predetermined pressure or higher. It is good also as a state.

  Next, the expansion joint 8B in which the exhaust duct 12 of the gas turbine 1 is interposed will be described.

  Since the exhaust gas flowing through the exhaust duct 12 has a high temperature exceeding 500 ° C., the exhaust duct 12 undergoes thermal expansion and contraction as the gas turbine 1 is activated and stopped. In order to absorb this thermal expansion and contraction, an expansion joint 8B is interposed in the exhaust duct 12.

  As shown in FIG. 5, the expansion joint 8B has flexible sealing films 15a and 16a fixed to the flanges 17 and 18 by a press plate 20 and bolts and nuts 21 with a spacer 19a interposed therebetween. Yes. A stud bolt 51 in which a heat insulating material layer 50 made of ceramic fiber, glass cloth or the like is welded to the outer peripheral surface of the exhaust duct 12 inside the flexible seal film 15a (center side of the exhaust duct 12), and It is attached by a nut 52 screwed into the bolt 51. The flexible seal films 15a and 16a may be made of a heat resistant material such as a tetrafluoropolyethylene resin sheet. The structure of the heat insulating material, the mounting structure of the flexible seal films 15a and 16a, the seal structure, and the like are not limited to the illustrated examples, and various structures can be employed.

In order to recover the residual heat from the high-temperature exhaust gas discharged from the gas turbine 1 and effectively use the exhaust heat, the exhaust duct 12 of the gas turbine 1 is connected to an exhaust gas boiler 55 (FIG. 1) for exhaust heat recovery. There are many cases. An exhaust fan, an air volume control damper, and the like (not shown) are installed in the flue of the exhaust gas. Therefore, the pressure Pin _in the exhaust duct 12 of the gas turbine 1 is slightly higher than atmospheric pressure. Furthermore, during operation of the gas turbine, the flexible sealing membrane 15a, 16a is air located between M of the sealed space expands due to the heat of the hot exhaust gas, becomes considerably higher pressure P _M than atmospheric pressure Yes. Expansion joint 8B of the exhaust duct 12 is disposed outside the enclosure 4 (see FIG. 1), the ambient atmospheric pressure P _out of the outer expansion joint 8B becomes the atmospheric pressure.

  Thus, during the operation of the gas turbine 1, M between the flexible seals 15a and 16a, the inside of the expansion joint 8B (inside the exhaust duct 12), and the outside of the expansion joint 8B (outside the exhaust duct 12) are respectively In different pressure conditions. Therefore, the deterioration of the expansion joint 8B can be detected by monitoring the differential pressure in these pressure states by the first differential pressure detector 30 and the second differential pressure detector 31. The pressure sensors 30a, 30b, 31a of the first and second differential pressure detectors 30, 31 are for high temperatures.

In the case of the expansion joint of the exhaust duct 12, as in the example shown in FIG. 3, the deterioration of the expansion joint 8B can be prevented by monitoring only the pressure P _M between the flexible seal films 15a and 15b. It can also be detected.

  In the above embodiment, only the example of the gas turbine is illustrated in the above embodiment, but the present invention can be applied to an incinerator and other combustion apparatuses.

It is a schematic block diagram which shows gas turbine power generation equipment. It is sectional drawing which shows the deterioration detection system of the expansion joint which concerns on this invention. It is sectional drawing which shows the change aspect of the deterioration detection system of the expansion joint which concerns on this invention. It is sectional drawing which shows other embodiment of the deterioration detection system of the expansion joint which concerns on this invention. It is sectional drawing which shows other embodiment of the deterioration detection system of the expansion joint which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas turbine 4 Enclosure 5 Intake duct 12 Exhaust duct 15 Flexible seal film | membrane 16 Flexible seal film | membrane 30 1st differential pressure | voltage detection part 31 2nd differential pressure | voltage detection part

Claims (3)

An expansion joint having at least two layers of a flexible sealing film hermetically connected to a seam of a metallic duct connected to a combustion device;
A pressure detecting means for detecting a pressure between at least the two layers of the flexible seal films, in order to detect deterioration of at least one of the two layers of the flexible seal films;
A deterioration detection system for an expansion joint, characterized by comprising: The pressure detecting means includes
A first differential pressure detection unit for detecting a differential pressure between the pressure between the two layers of flexible seal films and the pressure inside the expansion joint;
A second differential pressure detection unit for detecting a differential pressure between the pressure between the two layers of the flexible seal film and the pressure outside the expansion joint;
The deterioration detection system for an expansion joint according to claim 1, comprising: The combustion device is a gas turbine;
The expansion joint is connected to an intake duct of a gas turbine, and is disposed in an enclosure in which a ventilation fan is installed and accommodates the gas turbine.
The first differential pressure detection unit detects a differential pressure between a combustion air pressure in the expansion joint and a pressure between the two layers of flexible seal films,
The second differential pressure detection unit detects a differential pressure between an ambient atmospheric pressure surrounded by the enclosure outside the expansion joint and a pressure between the two layers of flexible seal films. The deterioration detection system of the expansion joint as described in 1 or 2.

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