JP6911235B2 - Corrosion prevention device for the rotating shaft of the furnace top pressure recovery turbine - Google Patents

Description

The present invention relates to a corrosion prevention device for a rotating shaft of a furnace top pressure recovery turbine that is rotationally driven by blast furnace gas.

The top pressure recovery turbine power generation equipment, which is used for power generation by installing a turbine in the exhaust gas path of the blast furnace plant, recovers the pressure energy of the blast furnace gas generated in the blast furnace of the steelworks as electric power by the turbine, and also recovers the pressure energy of the blast furnace. It controls the top pressure, and in recent years, it has become an extremely important facility for saving energy in steelworks and contributing to environmental conservation.

There are two types of top pressure recovery turbine power generation equipment, wet and dry. In the wet top pressure recovery turbine power generation equipment, the blast furnace gas emitted from the blast furnace is washed with water using a wet dust remover, and then the top of the furnace is used to drive the generator. It leads to a pressure recovery turbine. On the other hand, in the dry furnace top pressure recovery turbine power generation facility, the blast furnace gas is removed without being washed with water by the dry dust remover, so that the temperature of the blast furnace gas does not decrease and the recovered power is 25 to 25 to that of the wet type. It is 45% higher, and power can be recovered efficiently.

Both types of turbine top pressure recovery turbine power generation equipment do not require fuel to drive the turbine for power generation, so CO2 reduction and energy saving effects are extremely high. Currently, most blast furnaces in domestic steelworks are used. Is equipped with wet or dry furnace top pressure recovery turbine power generation equipment.

However, in the above-mentioned wet top pressure recovery turbine power generation equipment, as a result of washing the blast furnace gas with water by the wet dust remover, the blast furnace gas contains steam to a saturated state, and in the process of removing dust by the wet dust remover, for example. Corrosive components such as Cl and SO4 dissolve in the dust-removed water after dust cleaning, and a part of this dust-removed water flows into the turbine as mist along with the exhaust gas. On the other hand, in a dry-type furnace top pressure recovery turbine power generation facility, the corrosive components contained in the exhaust gas are not removed and are melted at a high concentration in the condensed mist generated in the turbine.

Therefore, in both wet and dry furnace top pressure recovery turbine power generation equipment, the corrosive components such as Cl and SO4 contained in these mists come into contact with the rotating shaft, Durbin blades, casing, etc. and corrode them. There is a problem of letting it.

To solve the problem that the rotating shaft, darbin blade, casing, etc. are corroded by the corrosive components such as Cl and SO4 contained in this mist, the conventional method is to remove the adhering dust and corrosive components by washing with water or the like. , The rotating shaft has been dealt with by a method such as applying anticorrosion coating (see, for example, Patent Documents 1 to 4).

Japanese Unexamined Patent Publication No. 07-011974 Japanese Unexamined Patent Publication No. 07-011973 Japanese Unexamined Patent Publication No. 2014-080872 Japanese Unexamined Patent Publication No. 2007-315364

However, with respect to the rotating shaft, the above-mentioned conventional anticorrosive coating alone may cause the rotating shaft to be directly exposed to mist containing a corrosive component due to peeling or deterioration of the anticorrosive coating itself. In addition, wear due to dust in the exhaust gas also shortens the life of the anticorrosive coating film, increasing the possibility of exposure to mist containing corrosive components.

In this way, when the rotating shaft is directly exposed to mist containing corrosive components with the passage of use time, a part of the rotating shaft, particularly the front and rear ends of the drum portion of the rotating shaft, corrodes while the rotating shaft moves. Since a large centrifugal stress is constantly applied by the blade, there is a problem that stress corrosion cracking may occur on the rotating shaft due to the end of the corroded drum part. ..

On the other hand, as shown in FIG. 3, pressurization with a shaft sealing nitrogen gas is performed in order to make the casings 100 and 101 arranged in front of and behind the drum portion and the rotating shaft 102 airtight, respectively. , There is a top pressure recovery turbine that is designed to prevent the ingress of blast furnace gas into the interior.

However, if the shaft sealing nitrogen gas is simply supplied between the casings 100 and 101 and the rotating shaft 102 to prevent the blast furnace gas from entering the inside, the shaft sealing nitrogen gas is discharged to the blast furnace gas path. It is difficult to finely control the pressure and flow of the nitrogen gas in the pocket portions 103 and 104, and it is not possible to prevent the blast furnace gas from entering the pocket portions 103 and 104. Therefore, it is not possible to prevent the front end portion 105 and the rear end portion 106 of the drum portion 102a from being corroded by the blast furnace gas only with the conventional nitrogen gas for shaft sealing.

On the other hand, a method of increasing the pressure of the shaft sealing nitrogen gas supplied between the casings 100 and 101 and the rotating shaft 102 or increasing the supply amount is also conceivable. Finely controlling the pressure and flow of the nitrogen gas in the pockets 103 and 104, which are the outlets to the blast furnace gas path, even though the amount of nitrogen gas that must be supplied increases only by increasing the pressure and volume. Is similarly difficult, and it is not possible to prevent the blast furnace gas from entering the pocket portions 103 and 104.

The present invention has been made to solve such a problem, and corrosion of the drum portion of the rotating shaft exposed in the pocket portion due to the blast furnace gas, particularly near the end portion, is prevented, and the rotation of the top pressure recovery turbine is prevented. An object of the present invention is to provide a rotary shaft structure of a furnace top pressure recovery turbine capable of significantly reducing the possibility of stress corrosion cracking of the shaft.

In order to solve the above-mentioned problems, the means adopted by the present invention is corrosion of the rotating shaft of the blast furnace top pressure recovery turbine, which is used in the furnace top pressure recovery turbine power generation facility and is rotationally driven by the blast furnace gas supplied from the blast furnace. A preventive device, a rotating shaft having a small-diameter shaft portion and a large-diameter drum portion, a moving blade attached to the drum portion to rotationally drive the rotating shaft by blast furnace gas, and an axial end portion of the drum portion. A casing that is disposed on the outside through an opening that is a gap of a constant width extending in an annular shape over the entire circumference to form an inner portion of the blast furnace gas path, and an axial end portion of the drum portion inside the opening. A pocket portion composed of an enlarged cavity formed between the blast furnace and the axial end portion of the blast furnace, a discharge port that passes through the inside of the casing and opens in the vicinity of the pocket portion or the pocket portion, and a blast furnace gas to the discharge port. It is equipped with a nitrogen gas supply path for supplying and a nitrogen gas supply mechanism for supplying high-pressure nitrogen gas to the nitrogen gas supply path.

In the above-mentioned corrosion prevention device for the rotary shaft of the furnace top pressure recovery turbine, an enlargement formed inside the opening, which is a gap having a constant width extending in a circumferential direction between the drum portion of the rotary shaft and the casing. Since high-pressure nitrogen gas is supplied to the hollow pocket portion from the discharge port that passes through the inside of the casing and opens in the pocket portion or in the vicinity of the pocket portion, the high-pressure nitrogen gas causes the blast furnace gas to enter the pocket portion. Even if the blast furnace gas enters the pocket, nitrogen substitution is immediately performed, and the blast furnace gas that has entered is discharged from the pocket to the blast furnace gas passage.

Therefore, corrosion of the drum portion of the rotating shaft exposed in the pocket portion, particularly by the blast furnace gas near the end portion, is prevented. Therefore, the possibility of stress corrosion cracking of the rotating shaft can be significantly reduced.

In the corrosion prevention device for the rotary shaft of the furnace top pressure recovery turbine, it is desirable that the high-pressure nitrogen gas discharged from the discharge port has a higher pressure than the blast furnace gas passing through the rotor blades.

In this way, the high-pressure nitrogen gas discharged from the discharge port has a higher pressure than the blast furnace gas passing through the moving blades, so that the high-pressure nitrogen gas makes it more certain that the blast furnace gas enters the pocket portion. Even if the blast furnace gas enters the pocket, nitrogen substitution is immediately performed, and the blast furnace gas that has entered is discharged from the pocket to the blast furnace gas passage more quickly.

Therefore, corrosion by the blast furnace gas near the rear end of the drum portion of the rotating shaft exposed in the pocket portion is further prevented. Therefore, the possibility of stress corrosion cracking of the rotating shaft can be further reduced.

In the corrosion prevention device for the rotary shaft of the furnace top pressure recovery turbine, it is desirable that the above-mentioned nitrogen gas supply paths are arranged at a plurality of locations in the circumferential direction of the casing.

By arranging the nitrogen gas supply paths at a plurality of locations in the circumferential direction of the casing in this way, high-pressure nitrogen gas is uniformly discharged from the nitrogen gas supply path into the pocket portion in the circumferential direction of the casing, and the blast furnace Gas is more reliably prohibited from entering the pocket. Therefore, the possibility of stress corrosion cracking of the rotating shaft can be further reduced.

In the corrosion prevention device for the rotary shaft of the furnace top pressure recovery turbine, the nitrogen gas supply path communicates from the nitrogen gas supply mechanism to the discharge port through a cavity extending in the circumferential direction arranged in the casing. It is desirable to be there.

In this way, since the nitrogen gas supply path communicates from the nitrogen gas supply mechanism to the discharge port of the nitrogen gas supply path through the cavity extending in the circumferential direction arranged in the casing, high-pressure nitrogen gas is released. By passing through this cavity that is continuous in the circumferential direction, pressure can be made uniform and pulsation can be prevented.

In the corrosion prevention device for the rotary shaft of the furnace top pressure recovery turbine, the shaft sealing nitrogen gas supplied from the nitrogen gas supply mechanism in a separate path from the nitrogen gas supply path between the casing and the rotary shaft is used. It is desirable that pressure be applied to prevent the entry of blast furnace gas into the interior.

In this way, the pressure applied to make the space between the casing and the rotating shaft airtight is different from the nitrogen gas supply path, and the shaft sealing nitrogen is supplied from the same nitrogen gas supply mechanism as the high-pressure nitrogen gas described above. By using gas, the entire nitrogen gas supply mechanism can be simplified.

The corrosion prevention device for the rotary shaft of the top pressure recovery turbine of the present invention is used in the top pressure recovery turbine power generation equipment and is rotationally driven by the blast furnace gas supplied from the blast furnace. Corrosion of the rotary shaft of the top pressure recovery turbine. A preventive device, a rotating shaft having a small-diameter shaft portion and a large-diameter drum portion, a moving blade attached to the drum portion and rotationally driving the rotating shaft by blast furnace gas, and an axial end portion of the drum portion. A casing that is disposed on the outside through an opening that is a gap of a constant width extending in an annular shape over the entire circumference to form an inner portion of the blast furnace gas passage, and an axial end portion of the drum portion inside the opening. A pocket portion consisting of an enlarged cavity formed between the axial end portion of the casing, a discharge port that passes through the inside of the casing and opens in the vicinity of the pocket portion or the pocket portion, and a blast furnace gas is supplied to the discharge port. It is provided with a turbine gas supply path and a blast furnace gas supply mechanism for supplying high-pressure blast furnace gas to the turbine gas supply path.

Therefore, corrosion of the drum portion of the rotating shaft exposed in the pocket portion, especially by the blast furnace gas near the end portion, can be prevented, and the possibility of stress corrosion cracking of the rotating shaft of the rotating shaft of the furnace top pressure recovery turbine can be significantly reduced. It has the excellent effect of being able to do it.

It is a partial cross-sectional view which shows the corrosion prevention device of the rotary shaft of the furnace top pressure recovery turbine which concerns on this invention. It is a schematic diagram which shows the nitrogen gas supply mechanism for supplying high pressure nitrogen gas to the furnace top pressure recovery turbine of FIG. It is a partial cross-sectional view which shows the corrosion prevention device of the rotary shaft of the conventional furnace top pressure recovery turbine.

A mode for implementing the corrosion prevention device for the rotary shaft of the furnace top pressure recovery turbine according to the present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 is a partial cross-sectional view showing a main part of a top pressure recovery turbine 1 installed in an exhaust gas path of a blast furnace plant of a top pressure recovery turbine power generation facility as an example to generate power. In the power generation equipment of the top pressure recovery turbine, the blast furnace gas supplied from the blast furnace is guided to the top pressure recovery turbine 1 via various devices and driven to rotate.

Power is generated by rotationally driving the generator by the rotating shaft 10 of the furnace top pressure recovery turbine 1. The rotating shaft 10 has a shaft portion 10b that is pivotally supported by bearings or the like at the front and rear, and a drum portion 10a that is formed to have a diameter larger than that of the shaft portion 10b. The drum portion 10a has a Christmas tree type. For example, a two-stage first-stage rotor blade (first-stage rotor blade) 11 and a second-stage rotor blade (final-stage rotor blade) 12 are attached via the mounting portion of the above.

That is, two stages (plurality of stages) of moving blades 11 and 12 are arranged on the rotary shaft 10 of the furnace top pressure recovery turbine 1, and a plurality of blades 11 and 12 of each stage are arranged in the circumferential direction. It is attached to form a speed-increasing blade row, and the rotating shaft 10 is rotationally driven by the action of blast furnace gas that passes through the moving blades 11 and 12 and adiabatically expands.

Reference numeral 13 is a forward extension portion of the first stage rotor blade (first stage rotor blade) 11 attached to the drum portion 10a of the rotating shaft 10, which is further forward than the front end portion of the platform 11a. , The rear extension portion of the second stage rotor blade (final stage rotor blade) 12 attached to the drum portion 10a of the rotating shaft 10 is further extended rearward from the rear end portion of the platform 12a. That is, in the rotary shaft 10 of the furnace top pressure recovery turbine 1, the portion of the drum portion 10a in contact with the blast furnace gas flow path is the front extension portion 13 and the rear extension portion, as compared with the rotation shaft of the conventional furnace top pressure recovery turbine. It is extended in the front-back direction by 14 minutes.

A protective member 15 that is formed separately from the rotating shaft 10 and is attached to the outer peripheral portion of the front extending portion 13 to cover the outer peripheral portion, and similarly formed separately from the rotating shaft 10 and extends backward. A protective member 16 that is attached to the outer peripheral portion of the protruding portion 14 and covers the outer peripheral portion is arranged. Each of these protective members 15 and 16 is composed of a plurality of protective member pieces formed separately in the circumferential direction.

As described above, the drum portion 10a of the rotating shaft 10 extends forward from the first stage rotor blade 11 and extends rearward from the second stage rotor blade 12. Since each of the protrusions 14 is provided, the front end (axial end) 18 of the front extension 13 of the drum portion 10a, which is particularly prone to corrosion due to blast furnace gas, and the rear end (axial direction) of the rear extension 14 By arranging the end portion) 19 at a position away from the moving blades 11 and 12, the stress value of the centrifugal stress received from the moving blades 11 and 12 is reduced. Therefore, the possibility of stress corrosion cracking of the rotating shaft 10 due to corrosion of the front and rear end portions 18 and 19 of the drum portion 10a can be reduced.

Further, the rotating shaft 10 is attached to the outer peripheral portion of the front extending portion 13 and the outer peripheral portion of the rear extending portion 14, and the protective members 15 and 16 covering these outer peripheral portions are attached. Therefore, it is possible to prevent the outer peripheral portions of the front extending portion 13 and the rear extending portion 14 from being directly exposed to the mist containing the corrosive component, which also reduces the possibility of stress corrosion cracking of the rotating shaft 10.

A protective member 17 similar to the protective members 15 and 16 described above is also attached to the outer peripheral portion of the drum portion 10a of the rotating shaft 10 between the first-stage rotor blade 11 and the second-stage rotor blade 12. The protective member 17 is also composed of a plurality of protective member bodies divided and formed in the circumferential direction. Therefore, the outer peripheral portion of the drum portion 10a of the rotating shaft 10 between the two-stage rotor blades 11 and 12, which has been directly exposed to the blast furnace gas, can be protected from the blast furnace gas, and stress corrosion of the rotating shaft 10 can be achieved. Further reduce the possibility of cracking.

The inlet casing 20 is arranged in front of the front end portion 18 of the front extending portion 13 of the drum portion 10a with a gap of a certain width provided, and the blast furnace gas passage 2 is provided between the inlet casing 20 and the central casing 30 on the outside thereof. To form. The inlet casing 20 forms the inner portion 3 of the blast furnace gas passage 2. An outer casing (not shown) is provided on the outer side of the central casing 30 forming the outer portion of the blast furnace gas passage 2.

Between the rear end portion (axial end portion) 22 of the inlet casing 20 and the front end portion 18 of the drum portion 10a of the rotating shaft 10, a front opening 26 having a constant width and extending in an annular shape over the entire circumference is provided. It is formed. Inside the front opening 26, a front pocket portion 24 formed of an enlarged cavity, which extends in an annular shape in the circumferential direction along the inner cylindrical inlet casing 20 and is expanded in the axial direction, for example, is arranged. Will be set up. The front opening 26 is opened by providing a gap of a certain width in the above-mentioned blast furnace gas passage 2.

The front nitrogen gas supply path 32 passes through the inside of the inlet casing 20 and opens into the front pocket portion 24 to form a discharge port 34. As will be described in detail later, nitrogen gas having a pressure higher than that of the blast furnace gas passing near the inlet of the first stage rotor blade 11 is directly discharged from the discharge port 34 into the front pocket portion 24. The discharge port 34 is not necessarily limited to the one that opens into the front pocket portion 24 as long as the high-pressure nitrogen gas can be effectively discharged into the front pocket portion 24, and the discharge port 34 is in the vicinity of the front pocket portion 24. It may open to.

Similarly, the outlet casing 21 is arranged behind the rear end portion 19 of the rotating shaft 10 with a gap having a constant width extending in an annular shape over the entire circumference, and a blast furnace gas passage 2 is provided between the outlet casing 21 and the central casing 30. Form. The outlet casing 21 forms the inner portion 4 of the blast furnace gas passage 2 in the same manner as the inlet casing 20. The outlet casing 21 is supported by the central casing 30 by a plurality of airfoil-shaped struts (also referred to as struts) (not shown).

A rear opening 27 having a constant width and extending in an annular shape over the entire circumference is provided between the front end (axial end) 23 of the outlet casing 21 and the rear end 19 of the drum portion 10a of the rotating shaft 10. It is formed. Inside the rear opening 27, an enlarged cavity extending in the circumferential direction along the inner cylindrical outlet casing 21 in an annular shape, extending in an annular direction in the circumferential direction, and expanding in the axial direction, for example, The rear pocket portion 25 is arranged. The rear opening 27 is opened by providing a gap of a certain width in the above-mentioned blast furnace gas passage 2.

The rear nitrogen gas supply path 33 passes through the inside of the outlet casing 21 and opens into the rear pocket portion 25 to form a discharge port 35. As will be described in detail later, nitrogen gas having a pressure higher than that of the blast furnace gas passing near the outlet of the second stage rotor blade 12 is directly discharged into the rear pocket portion 25 from the discharge port 35. The discharge port 35 is not necessarily limited to the one that opens into the rear pocket portion 25 as long as the above-mentioned high-pressure nitrogen gas can be effectively discharged into the rear pocket portion 25. It may open in the vicinity of.

The above-mentioned front nitrogen gas supply passage 32 and its discharge port 34 are arranged at three locations (plural locations) in the circumferential direction of the inlet casing 20. Similarly, the rear nitrogen gas supply passage 33 and its discharge port 35 are arranged at two locations (plural locations) in the circumferential direction of the outlet casing 21. In the above-mentioned front and rear pocket portions 24 and 25, even if the blast furnace gas containing dust and the like enters between the rotating shaft 10 and the casings 20 and 21 through the front and rear openings 26 and 27, the dust and the like enter the front and rear pocket portions 24 and 25. It stays or adheres to the pockets 24 and 25 so as not to enter the inside further than the pockets 24 and 25.

As shown in FIG. 2, the nitrogen gas supply mechanism 40 is configured as follows. The nitrogen gas supply path 42 is branched into a front nitrogen gas supply path 44 and a rear nitrogen gas supply path 45 after passing through the pressure control valve 43 from the nitrogen gas supply source 41. The forward nitrogen gas supply path 44 is further branched into two paths through the flow rate regulating valve 47 and the pressure regulating valve 48. The front nitrogen gas supply passages 44, which are branched into the two passages and exit the nitrogen gas supply mechanism 40, enter the central casing 30, respectively.

The front nitrogen gas supply path 44 branched into two paths enters the front cavity portion (cavity portion) 36 arranged in the inlet casing 20 and extending in the circumferential direction. The front cavity portion 36 is formed in an annular shape in the inlet casing 20. The front nitrogen gas supply path 44 is branched into three paths at the outlet of the front cavity 36, and then communicates with the discharge port 34 of the front nitrogen gas supply path 44 shown in FIG.

In this way, the front nitrogen gas supply path 44 extends from the nitrogen gas supply mechanism 40 to the discharge port 34 of the front nitrogen gas supply path 44 via the front cavity portion 36 arranged in the inlet casing 20 in the circumferential direction. Since the high-pressure nitrogen gas is communicated with each other, the high-pressure nitrogen gas once passes through the front cavity portion 36 extending in the circumferential direction, thereby preventing the pulsation of the high-pressure nitrogen gas and making the pressure uniform.

On the other hand, the rear nitrogen gas supply path 45 is branched into two paths through the flow rate regulating valve 50 and the pressure regulating valve 51. The rear nitrogen gas supply path 45, which is branched into these two paths and exits the nitrogen gas supply mechanism 40, enters the outlet casing 21. After that, the rear nitrogen gas supply path 45 passes through the internal pipe of the outlet casing 21 and communicates with the discharge port 35 of the rear nitrogen gas supply path 45 shown in FIG.

After the pressure is adjusted by the pressure control valve 43 from the nitrogen gas supply source 41 of the nitrogen gas supply mechanism 40, the high-pressure nitrogen gas passes through the branched front nitrogen gas supply path 44 and is passed through the branched front nitrogen gas supply path 44 by the flow rate control valve 47 to the front pocket portion 24. The flow rate is adjusted so as to have a mass flow rate of, for example, 0.7 to 1.0 times that of the shaft-sealing nitrogen gas to be discharged to the blast furnace gas passage 2 through the gas passage 2.

The subsequent pressure control valve 48 increases the pressure at the discharge port 34 by, for example, 0.2 to 0.5 kgf / cm2, with respect to the blast furnace gas passing through the blast furnace gas passage 2 near the inlet of the first stage moving blade 11. The gas is directly discharged into the front pocket portion 24 from the discharge port 34 of the front nitrogen gas supply path 44 shown in FIG. 1 through the front cavity portion 36 which is adjusted and further arranged in the inlet casing 20.

Therefore, the high-pressure nitrogen gas directly discharged into the front pocket portion 24 prohibits the blast furnace gas from entering the front pocket portion 24, and even if a part of the blast furnace gas enters the front pocket portion 24 immediately. Nitrogen substitution is performed, and the blast furnace gas is rapidly discharged from the front pocket portion 24 to the blast furnace gas passage 2. Therefore, corrosion by the blast furnace gas in the vicinity of the front end portion 18 of the drum portion 10a exposed in the front pocket portion 24 is prevented. Therefore, the possibility of stress corrosion cracking of the rotating shaft 10 is greatly reduced.

Similarly, after the pressure is adjusted by the pressure control valve 43 from the nitrogen gas supply source 41 of the nitrogen gas supply mechanism 40, the high-pressure nitrogen gas passes through the branched rear nitrogen gas supply path 45 and is rearward by the flow rate control valve 50. The flow rate is adjusted so that the mass flow rate of the shaft-sealing nitrogen gas, which will be described later, discharged to the blast furnace gas passage 2 through the pocket portion 25 is, for example, 0.7 to 1.0 times.

The subsequent pressure control valve 51 increases the pressure at the discharge port 35 by, for example, 0.2 to 0.5 kgf / cm2, with respect to the blast furnace gas passing through the blast furnace gas passage 2 near the outlet of the second stage moving blade 12. After being adjusted, the gas is directly discharged from the discharge port 35 of the rear nitrogen gas supply path 45 shown in FIG. 1 into the rear pocket portion 25 through the outlet casing 21.

Therefore, the high-pressure nitrogen gas discharged directly into the rear pocket portion 25 prohibits the blast furnace gas from entering the rear pocket portion 25, and even if the blast furnace gas enters, nitrogen substitution is performed immediately. The blast furnace gas is quickly discharged from the rear pocket portion 25 into the blast furnace gas passage 2. Therefore, corrosion by the blast furnace gas in the vicinity of the rear end portion 19 of the drum portion 10a exposed in the rear pocket portion 25 is prevented. Therefore, the possibility of stress corrosion cracking of the rotating shaft 10 is greatly reduced.

The upper and lower limits of the flow rate and pressure of the high-pressure nitrogen gas supplied to the pockets 24 and 25 are related to the amount of high-pressure nitrogen gas to be supplied, and the blast furnace gas enters the pockets 24 and 25. It exemplifies the range in which the prohibition and the discharge of the blast furnace gas once entered from the pockets 24 and 25 can be performed most effectively, and the flow rate and pressure of the high-pressure nitrogen gas supplied to the pockets 24 and 25. Is not necessarily limited to the above range. It will be adjusted as needed.

On the other hand, another nitrogen gas supply path 52, which is branched from the nitrogen gas supply source 41 of the nitrogen gas supply mechanism 40 and is shown by a broken line in FIG. 2, rotates between the shaft portion 10b of the rotating shaft 10 and the inlet casing 20. Nitrogen gas for sealing the shaft is supplied to make the space between the shaft portion 10b of the shaft 10 and the outlet casing 21 airtight.

As shown in FIG. 2, the shaft sealing nitrogen gas passes between the shaft portion 10b of the rotating shaft 10 and the inlet casing 20, and between the shaft portion 10b of the rotating shaft 10 and the outlet casing 21, respectively. Finally, it is discharged into the above-mentioned front and rear pocket portions 24 and 25. In the front and rear pocket portions 24 and 25, they are mixed with the above-mentioned high-pressure nitrogen gas for nitrogen replacement and discharged to the blast furnace gas passage 2, respectively.

Due to this shaft sealing nitrogen gas, even if a small amount of blast furnace gas enters the front pocket portion 24 or the rear pocket portion 25, the inside or the rotating shaft between the shaft portion 10b of the rotating shaft 10 and the inlet casing 20 Further entry of blast furnace gas into the interior between the shaft portion 10b of 10 and the outlet casing 21 is prevented.

Therefore, internal corrosion of the rotating shaft 10, the inlet casing 20, and the outlet casing 21 is reliably prevented. This nitrogen gas for shaft sealing is also supplied from the nitrogen gas supply mechanism 40 described above. Therefore, the entire nitrogen gas supply mechanism of the furnace top pressure recovery turbine 1 can be extremely simplified.

Further, since the above-mentioned nitrogen gas supply passages 44 and 45 are arranged at a plurality of locations in the circumferential direction of the inlet and outlet casings 20 and 21, the front and rear pocket portions 24 and 25 from the nitrogen gas supply mechanism 40 are included. The high-pressure nitrogen gas is uniformly discharged to the inlet and outlet casings 20 and 21 in the circumferential direction, and the blast furnace gas is surely prevented from entering the front and rear pocket portions 24 and 25. Therefore, the possibility of stress corrosion cracking of the rotating shaft can be further reduced.

The above-mentioned corrosion prevention device for the furnace top pressure recovery turbine is only an example, and various modifications can be made based on the gist of the present invention, and these are not excluded from the scope of the present invention.

1 Furnace top pressure recovery turbine 2 Blast furnace gas passage 3, 4 Inner part 10 Rotating shaft 10a Drum part 10b Shaft part 11 First stage rotor blade (first stage rotor blade)
11a Platform 12 Second stage rotor blade (final stage rotor blade)
12a Platform 13 Front extension 14 Rear extension 15, 16, 17 Protective member 18 Front end (axial end)
19 Rear end (axial end)
20 Inlet casing 21 Outlet casing 22 Rear end (axial end)
23 Front end (axial end)
24 Front pocket 25 Rear pocket 26 Front opening 27 Rear opening 30 Central casing 32 Front nitrogen gas supply path 33 Rear nitrogen gas supply path 34, 35 Discharge port 36 Front cavity (cavity)
40 Nitrogen gas supply mechanism 41 Nitrogen gas supply source 42 Nitrogen gas supply path 43 Pressure control valve 44 Front nitrogen gas supply path 45 Rear nitrogen gas supply path 47 Flow control valve 48 Pressure control valve 50 Flow control valve 51 Pressure control valve 52 Nitrogen gas Supply path 100, 101 Casing 102 Rotating shaft 102a Drum part 103, 104 Pocket part 105 Front end part 106 Rear end part

Claims (4)

Top pressure recovery turbine A corrosion prevention device for the rotating shaft of the top pressure recovery turbine (1), which is used in power generation equipment and is rotationally driven by blast furnace gas supplied from the blast furnace, and has a small diameter shaft (10b). A rotating shaft (10) having a large-diameter drum portion (10a), a moving blade (11, 12) attached to the drum portion and rotationally driving the rotating shaft by the blast furnace gas, and a shaft of the drum portion. The inner part (3,4) of the blast furnace gas passage (2) is arranged through an opening (26,27) which is a gap having a constant width extending in a ring shape over the entire circumference on the outer side of the directional end (18, 19). ), And an enlargement formed inside the opening and between the axial end of the drum and the axial end of the casing (22, 23). From the hollow pocket portion (24, 25), the discharge port (34, 35) that passes through the inside of the casing and opens in the vicinity of the pocket portion or the pocket portion, and the blast furnace gas that passes through the turbine blade. It is also characterized by having a nitrogen gas supply path (44, 45) for supplying high-pressure nitrogen gas to the discharge port and a nitrogen gas supply mechanism (40) for supplying the nitrogen gas to the nitrogen gas supply path. A device for preventing corrosion of the rotating shaft of the furnace top pressure recovery turbine. The rotation of the furnace top pressure recovery turbine according to claim 1, wherein the nitrogen gas supply passages (44, 45) are arranged at a plurality of locations in the circumferential direction in the casing (20, 21). Shaft corrosion protection device. The nitrogen gas supply paths (44) arranged at a plurality of locations in the circumferential direction in the casing (20) are discharged through the cavity portions (36) arranged in the casing in the circumferential direction. The corrosion prevention device for a rotary shaft of a furnace top pressure recovery turbine according to claim 2 , wherein the turbine communicates with the outlet (34). The shaft sealing nitrogen supplied from the nitrogen gas supply mechanism (40) is separated from the nitrogen gas supply path (44, 45) between the casing (20, 21) and the rotating shaft (10). The corrosion prevention device for a rotary shaft of a furnace top pressure recovery turbine according to any one of claims 1 to 3, wherein the blast furnace gas is pressurized by gas to prevent the blast furnace gas from entering the inside.

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