JP7432148B2 - Loop seal inner cylinder support structure - Google Patents

Description

The present disclosure relates to an inner cylinder support structure for a loop seal.

Generally, a loop seal is provided in a circulating fluidized bed boiler that includes a furnace for burning fuel and a cyclone for separating particles such as sand and ash from the combustion gas discharged from the furnace.

The loop seal has a casing suspended from a leg pipe of the cyclone, and a return pipe extending from the casing connected to the bottom of the furnace.

An inner cylinder for introducing particles is installed inside the casing of the loop seal, and by burying the lower part of the inner cylinder inside the particles, the pressure difference between the cyclone and the furnace is sealed, and the combustion gas in the furnace is This allows the particles separated by the cyclone to be stably returned to the furnace while preventing them from flowing back into the cyclone.

In the case of a conventional loop seal, an annular support hardware is projected from the inner surface of the upper end of the casing, the flange of the inner cylinder is placed on the support, and the upper and lower surfaces of the flange are covered with a refractory material. The structure is such that the inner cylinder is supported.

Note that, for example, Patent Document 1 shows the general technical level of loop seals for circulating fluidized bed boilers.

Patent No. 3897508

Incidentally, although high-temperature combustion gas is flowing inside the inner cylinder, the flange part, which is placed on the supporting hardware protruding from the casing, loses heat to the outside via the supporting hardware. , the temperature will be lower than inside.

Therefore, the elongation of the flange portion becomes smaller than the elongation of the inner cylinder in the radial direction, which becomes relatively hot, and as a result, the flange portion deforms to contract the inner cylinder. When such deformation occurs, even if the upper and lower surfaces of the flange portion are covered with fireproof material, a gap is created at the outer peripheral end of the flange portion, and particles such as sand and ash enter the gap, causing the The thermal expansion of the flange portion is inhibited, and the deformation of the flange portion to contract the inner cylinder is further promoted. Once the deformation progresses to a certain extent, the load on the welded part of the inner cylinder, which is the structurally weakest part of the flange, increases, and improvements have been desired.

Therefore, in the present disclosure, in view of the above conventional problems, an inner cylinder support structure of a loop seal that can minimize the temperature difference at the flange portion will be described.

The present disclosure provides a casing in which particles separated by a cyclone and flowing down from a leg pipe of the cyclone are temporarily stored;
an inner cylinder arranged to introduce the particles into the casing, and whose lower part is buried inside the particles;
and a return pipe connected to the upper side surface of the casing and discharging particles, the loop seal inner cylinder support structure comprising:
a flange portion formed at the upper end of the inner cylinder;
an inner step part formed by expanding the inner diameter of the leg pipe of the cyclone so that the flange part is exposed and placed inside the leg pipe of the cyclone ;
Suspension reinforcing material disposed at an outer step formed between the outer periphery of the leg pipe and the outer periphery of the casing as the inner step is formed;
The present invention relates to an inner cylinder support structure for a loop seal.

In the inner cylinder support structure of the loop seal, the flange portion includes:
a lower flange placed on the inner step;
an upper flange disposed upwardly from the lower flange at a required interval;
It is preferable to include ribs arranged radially from the center of the flange portion so as to connect the lower flange and the upper flange.

Moreover, in the inner cylinder support structure of the loop seal, it is preferable that the lower flange is welded to the outer periphery of the inner cylinder, and the upper flange is welded to the outer periphery of the inner cylinder.

Further, in the inner cylinder support structure of the loop seal, it is preferable that the upper surface of the outer peripheral end of the lower flange is provided with a taper formed so as to have a downward slope from the inner peripheral side to the outer peripheral side.

Furthermore, in the inner cylinder support structure of the loop seal, a holding beam that extends from the inner surface of the casing of the loop seal toward the inner cylinder side and is arranged in multiple stages in the vertical direction;
It is preferable to include a receiving member provided on the inner cylinder so as to sandwich the holding beam from both sides in the circumferential direction.

Further, in the loop seal inner cylinder support structure, it is preferable that a guide dam is formed inside the leg pipe of the cyclone, the guide weir being located above the flange portion and having an inner diameter smaller than the inner diameter of the inner cylinder.

Further, in the inner cylinder support structure of the loop seal, the loop seal is installed in a circulating fluidized bed boiler equipped with a furnace for burning fuel and the cyclone for separating particles in combustion gas discharged from the furnace. and the return pipe is preferably connected to the furnace.

According to the inner cylinder support structure of the loop seal of the present invention, an excellent effect can be achieved in that the temperature difference at the flange portion can be minimized.

FIG. 7 is a side cross-sectional view of a main part illustrating a form of an inner cylinder support structure of a loop seal according to an embodiment of the present disclosure, and is an enlarged view of part I in FIG. 6. FIG. FIG. 2 is a plan view showing the lower flange and suspension reinforcement of the inner cylinder support structure of the loop seal according to the embodiment of the present disclosure, and is a view corresponding to the II-II arrow in FIG. 1; FIG. 7 is a side sectional view of a main part showing the lower steady stop mechanism of the inner cylinder support structure of the loop seal according to the embodiment of the present disclosure, and is an enlarged view of section III in FIG. 6. 4 is a plan view showing the lower steady stop mechanism of the inner cylinder support structure of the loop seal according to the embodiment of the present disclosure, and is a view corresponding to the IV-IV arrow in FIG. 3. FIG. FIG. 3 is a side sectional view showing the upper steady stop mechanism of the inner cylinder support structure of the loop seal according to the embodiment of the present disclosure, and is a view corresponding to the VV arrow in FIG. 2; 1 is an overall view showing a circulating fluidized bed boiler to which a loop seal inner cylinder support structure according to an embodiment of the present disclosure is applied.

Hereinafter, embodiments of the present invention in the present disclosure will be described with reference to the accompanying drawings.

The loop seal inner cylinder support structure according to the embodiment of the present disclosure is applied to, for example, a circulating fluidized bed boiler. As shown in FIG. 6, the circulating fluidized bed boiler includes a furnace 100, a cyclone 200, a loop seal 300, and a rear heat transfer section 400.

The furnace 100 burns the fuel while fluidizing it together with a bed material made of sand, limestone, etc., using air blown out from an air distribution nozzle 110.

The cyclone 200 is connected to the upper part of the furnace 100 and collects particles such as sand and ash contained in the combustion gas generated by combustion within the furnace 100. Incidentally, the cyclone 200 includes a swirling introduction section 210, a particle separation and collection section 220, an outlet duct 230, and an inner cylinder 240. The swirling introduction section 210 is a part where the gas containing particles is introduced to form a swirling flow. The particle separation and recovery section 220 is a section that is provided at the lower end of the swirl introduction section 210 and whose diameter is reduced downward. The outlet duct 230 is connected to the upper end of the swirl introduction part 210. The inner cylinder 240 is installed inside the swirl introduction part 210 to guide the gas from which particles have been separated to the outlet duct 230. Note that the cyclone 200 is supported by support legs 250. Further, a leg pipe 260 is connected to the lower end of the particle separation and collection section 220.

The loop seal 300 includes a casing 301, an inner cylinder 310, and a return pipe 330. The casing 301 temporarily stores particles separated by the cyclone 200 and flowing down from the leg pipe 260. The inner cylinder 310 is arranged so as to introduce the particles into the inside of the casing 301, and the lower part thereof is buried inside the particles. The return pipe 330 is connected to the upper side of the casing 301 and discharges particles back to the bottom of the furnace 100. Note that an air dispersion nozzle 320 is provided at the bottom of the casing 301 to blow out air to fluidize the particles. Incidentally, even if the pressure in the lower part of the furnace 100 is higher than the pressure in the lower part of the cyclone 200, the loop seal 300 prevents the combustion gas in the furnace 100 from flowing back to the cyclone 200 side. Particles such as sand and ash separated in the furnace 200 can be stably returned to the furnace 100.

The rear heat transfer section 400 receives combustion gas from which particles such as sand and ash have been collected by the cyclone 200, and has a heat transfer tube group 410 constituting a superheater, reheater, economizer, etc. inside. The heat of the combustion gas is recovered and used for power generation.

In the case of this embodiment, as shown in FIGS. 1 and 2, a flange portion 311 is formed at the upper end of the inner cylinder 310, and the flange portion 311 is exposed inside the leg pipe 260 of the cyclone 200. It is characterized in that the inner diameter of the leg tube 260 is expanded to form an inner stepped portion 261 so that the leg tube 260 can be placed thereon. The inner diameter of the leg tube 260 is expanded over the entire length of the leg tube 260 in the vertical direction.

The inner step portion 261 is formed by displacing the inner circumferential surface position of the refractory material 262 that covers the inner surface of the leg pipe 260 to the outer circumferential side from the inner circumferential surface position of the refractory material 302 that covers the inner surface of the casing 301 of the loop seal 300. The upper surface of the inner cylinder support member 303 disposed on the inner peripheral surface of the upper end portion of the casing 301 of the loop seal 300 is exposed. The inner cylinder support member 303 includes a support bracket 304 that protrudes from the inner surface of the casing 301 of the loop seal 300, and an annular plate 305 placed on the support bracket 304.

Incidentally, the refractory material 262 and the refractory material 302 are intentionally shown by imaginary lines in FIGS. 1, 3, and 5. This is to clearly show the inner cylinder support member 303 as well as the reinforcing bracket 263 disposed on the inner surface of the lower end of the leg tube 260.

With the formation of the inner step 261, an outer step 264 is created between the outer periphery of the leg tube 260 and the outer periphery of the casing 301 of the loop seal 300. For this reason, a hanging reinforcing member 265 is attached to the outer step portion 264 so that the weight of the loop seal 300 is supported by the hanging reinforcing member 265. The suspension reinforcing member 265 includes a base material 266 welded to the outer periphery of the leg pipe 260 so as to extend in the vertical direction, and an upper part welded to the base material 266 and suspended, and a lower end part attached to the casing 301 of the loop seal 300. A holding member 267 to be welded is provided. As shown in FIG. 2, the base member 266 is made of T-beam steel, and the holding member 267 is made of H-beam steel. However, it goes without saying that the base material 266 and the holding material 267 may each be made of angle steel, channel steel, or members formed by bending metal plates.

Further, the flange portion 311 can be composed of one flange, but in the case of this embodiment, it includes a lower flange 312, an upper flange 313, and a rib 314. The lower flange 312 is welded to the outer periphery of the inner cylinder 310 and placed on the inner step 261. More specifically, as shown in FIG. 1, the lower flange 312 is placed on the upper surface of the annular plate 305. The upper flange 313 is welded to the outer periphery of the inner cylinder 310 at a required distance upward from the lower flange 312. The ribs 314 are welded to connect the lower flange 312 and the upper flange 313, and are arranged radially from the inner circumferential side to the outer circumferential side of the flange portion 311, as shown in FIG.

Furthermore, a taper 315 is formed on the upper surface of the outer peripheral end of the lower flange 312 so as to slope downward from the inner peripheral side to the outer peripheral side.

Further, as shown in FIGS. 3 and 4, the lower portion of the inner cylinder 310 is restrained from moving in the turning direction (circumferential direction) and radial direction by a lower steady stop mechanism 340. The lower steady rest mechanism 340 includes a holding beam 341 and a receiving member 342. The holding beams 341 extend from the inner surface of the casing 301 of the loop seal 300 toward the inner cylinder 310 side, and are arranged at multiple locations (for example, four locations) in the circumferential direction and in multiple stages (for example, two stages) in the vertical direction. There is. The receiving member 342 includes a cylindrical body 344 attached to the lower outer periphery of the inner cylinder 310 via a fixture 343, and a cylindrical body 344 that protrudes from the outer periphery of the cylindrical body 344 so as to sandwich the tip end of the holding beam 341 from both sides in the circumferential direction. A clamping piece 345 is provided.

As shown in FIGS. 2 and 5, the upper portion of the inner cylinder 310 is restrained from moving in the turning direction (circumferential direction) and radial direction by an upper steady stop mechanism 350. The upper steady stop mechanism 350 includes a protruding piece 351 and a groove 352. The protruding piece 351 is fixed such that its upper part protrudes from the upper surface of the annular plate 305 and its lower part is embedded in the annular plate 305 and the refractory material 262. The groove 352 is formed in the lower flange 312 so as to engage with the protrusion 351 .

A guide weir 268 is formed inside the leg pipe 260 of the cyclone 200, as shown in FIGS. 1 and 5. The guide weir 268 is located above the flange portion 311 and is formed of a refractory material 262 so that its inner diameter d is smaller than the inner diameter D of the inner cylinder 310. The guide weir 268 has a descending conical surface 268a whose inner diameter is gradually reduced from above to below to d, a cylindrical surface 268b that hangs down from the lower end of the descending conical surface 268a and has a uniform inner diameter of d, and the cylindrical surface. It has a diverging conical surface 268c whose inner diameter gradually expands downward from the lower end of 268b.

Next, the operation of the above embodiment will be explained.

By expanding the inner diameter of the leg tube 260 to form the inner step portion 261, the flange portion 311 formed at the upper end of the inner cylinder 310 is exposed and placed inside the leg tube 260.

The flange portion 311, like the inner cylinder 310, is exposed to high-temperature combustion gas, and the temperature does not decrease without losing heat to the outside.

Therefore, no relative temperature difference occurs between the flange portion 311 and the inner cylinder 310, and the elongation of the flange portion 311 is not smaller than the elongation of the inner cylinder 310 in the radial direction. This prevents the flange portion 311 from deforming so as to contract the inner cylinder 310.

When the temperature difference between the flange part 311 and the inner cylinder 310 is eliminated and no deformation occurs, the load on the welded part of the flange part 311 to the inner cylinder 310, which is structurally the weakest, is significantly reduced.

On the other hand, as the inner step portion 261 is formed, an outer step portion 264 is formed between the outer circumference of the leg tube 260 and the outer circumference of the casing 301 of the loop seal 300. The outer step portion 264 is a so-called discontinuous portion in which the casing 301 of the loop seal 300 does not simply hang down from the leg pipe 260 but is bent. However, a base material 266 constituting a suspension reinforcing material 265 is welded to the outer periphery of the leg pipe 260, and the upper part of a holding material 267 is welded to and suspended from the base material 266. The lower end portion is welded to the casing 301 of the loop seal 300. Therefore, the weight of the loop seal 300 is stably supported by the suspension reinforcing member 265, and the casing 301 of the loop seal 300 is not deformed.

Further, the lower flange 312 constituting the flange portion 311 is welded to the outer periphery of the inner tube 310 and placed on the inner step portion 261, and as shown in FIG. It is placed on the top. The upper flange 313 constituting the flange portion 311 is welded to the outer periphery of the inner cylinder 310 at a required distance upward from the lower flange 312. The ribs 314 constituting the flange portion 311 are welded to connect the lower flange 312 and the upper flange 313, and are arranged radially from the inner circumferential side to the outer circumferential side of the flange portion 311, as shown in FIG. There is. As a result, the strength of the entire inner cylinder 310 including the flange portion 311 is improved, and a structure that is resistant to deformation can be achieved. Here, if there are welded parts of the lower flange 312 and upper flange 313 on the inner circumference of the inner cylinder 310, when the inner cylinder 310 undergoes thermal expansion deformation, the maximum bending stress will be concentrated on the welded parts. It works. However, since the welded portion of the lower flange 312 and the upper flange 313 exists on the outer periphery of the inner cylinder 310, even if the inner cylinder 310 undergoes thermal expansion deformation, the maximum bending stress will concentrate on the welded portion. can be avoided.

Furthermore, by exposing the flange portion 311, there is an increased possibility that particles such as sand and ash will accumulate at the tip of the lower flange 312 of the flange portion 311, thereby inhibiting thermal expansion of the flange portion 311. However, even if particles such as sand or ash accumulate on the tip of the lower flange 312 of the flange portion 311, the upper surface of the outer peripheral end of the lower flange 312 will have a downward slope from the inner peripheral side to the outer peripheral side. A taper 315 is formed. Therefore, the taper 315 acts like a wedge and easily penetrates into the particles, so that thermal expansion of the flange portion 311 is not inhibited.

Moreover, inside the leg pipe 260 of the cyclone 200, as shown in FIGS. 1 and 5, a guide weir 268 is formed which includes a downstream conical surface 268a, a cylindrical surface 268b, and a diverging conical surface 268c. Therefore, the particles are stably guided into the inner cylinder 310 from the downstream conical surface 268a of the guide weir 268 via the cylindrical surface 268b, and are difficult to go to the diverging conical surface 268c side, so that they directly reach the flange portion 311. Avoid being hit.

Furthermore, the particles temporarily stored in the loop seal 300 are fluidized by the air blown out from the air dispersion nozzle 320, and the lower part of the inner cylinder 310 is buried inside the particles. Vibrations become louder. However, in the lower part of the inner cylinder 310, as shown in FIGS. 3 and 4, a clamping piece 345 protruding from the cylindrical body 344 of the receiving member 342 of the lower steady-stop mechanism 340 is inserted from the inner surface of the casing 301 toward the inner cylinder 310. By engaging with the distal end of the holding beam 341 extending out, movement in the turning direction and the radial direction is suppressed, and stable support is achieved. Moreover, since the holding beams 341 of the lower steady stop mechanism 340 are arranged in multiple stages (for example, two stages) in the vertical direction, they are effective in further suppressing vibrations of the inner cylinder 310.

As shown in FIGS. 2 and 5, the upper part of the inner cylinder 310 is rotated in the turning direction by the groove 352 of the upper steady-stop mechanism 350 engaging with the protruding piece 351 protruding from the upper surface of the annular plate 305. In addition, radial movement is suppressed and stably supported.

In this way, the temperature difference in the flange portion 311 can be minimized.

In the case of this embodiment, suspension reinforcement is provided on the outer step 264 that is generated between the outer periphery of the leg pipe 260 and the outer periphery of the casing 301 of the loop seal 300 as the inner step 261 is formed. A material 265 is provided. With this structure, even if there is a so-called discontinuous part called the outer step part 264 between the leg pipe 260 and the loop seal 300, which does not simply hang but is bent, the suspension reinforcing member 265, the weight of the loop seal 300 is stably supported.

Further, the flange portion 311 includes a lower flange 312 placed on the inner step portion 261, an upper flange 313 disposed upwardly from the lower flange 312 at a required distance, and a lower flange 313 disposed above the lower flange 312. The ribs 314 are arranged radially from the inner circumferential side to the outer circumferential side of the flange portion 311 so as to connect with the flange 313 . This configuration is effective in improving the strength of the entire inner cylinder 310 including the flange portion 311 and providing a structure that is resistant to deformation.

Further, the lower flange 312 is welded to the outer periphery of the inner cylinder 310, and the upper flange 243 is welded to the outer periphery of the inner cylinder 310. If the welded parts of the lower flange 312 and the upper flange 243 are present on the inner circumference of the inner cylinder 310, when the inner cylinder 310 undergoes thermal expansion and deformation, the maximum bending stress will concentrate on the welded parts. However, if the welded portion of the lower flange 312 and the upper flange 243 exists on the outer periphery of the inner cylinder 310, even if the inner cylinder 310 undergoes thermal expansion deformation, the maximum bending stress will be concentrated at the welded portion. It is advantageous because it does not affect.

Furthermore, a taper 315 is provided on the upper surface of the outer peripheral end of the lower flange 312 so as to slope downward from the inner peripheral side to the outer peripheral side. With this configuration, when particles are deposited on the tip of the lower flange 312 of the flange portion 311, the taper 315 acts like a wedge to make it easier for the particles to enter the particles. This is effective for smooth thermal elongation.

Further, a holding beam 341 is extended from the inner surface of the casing 301 of the loop seal 300 toward the inner cylinder 310 side and is arranged in multiple stages in the vertical direction, and a holding beam 341 is attached to the inner cylinder 310 so as to sandwich the holding beam 341 from both sides in the circumferential direction. A receiving member 342 is provided. With this configuration, it is possible to stably support the inner cylinder 310 whose lower part is buried inside the particles and whose vibrations tend to increase.

Further, a guide weir 268 is formed inside the leg pipe 260 of the cyclone 200, and is located above the flange portion 311 and has an inner diameter d smaller than the inner diameter D of the inner cylinder 310. With this configuration, the particles can be stably guided into the inner cylinder 310 and contact of the particles with the flange portion 311 can be avoided.

Further, the loop seal 300 is installed in a circulating fluidized bed boiler equipped with a furnace 100 that burns fuel and the cyclone 200 that separates particles in combustion gas discharged from the furnace 100, and the loop seal 300 is installed in a circulating fluidized bed boiler that includes a furnace 100 that burns fuel and the cyclone 200 that separates particles in combustion gas discharged from the furnace 100. is connected to the furnace 100. With this configuration, in particular, the loop seal 300 provided in the circulating fluidized bed boiler can be operated stably.

Note that the inner cylinder support structure of the loop seal of the present invention is not limited to the above-described embodiments described in the present disclosure, and various changes may be made without departing from the gist of the present invention. Of course.

100 Furnace 110 Air dispersion nozzle 200 Cyclone 210 Rotating introduction section 220 Particle separation and recovery section 230 Outlet duct 240 Inner cylinder 250 Support leg 260 Leg pipe 261 Inner step 262 Refractory material 263 Reinforcement bracket 264 Outer step 265 Suspension reinforcing material 266 Base Material 267 Holding material 268 Guide weir 268a Downward conical surface 268b Cylindrical surface 268c Wide conical surface 300 Loop seal 301 Casing 302 Refractory material 303 Inner cylinder support member 304 Support bracket 305 Annular plate 310 Inner cylinder 311 Flange portion 312 Lower flange 313 Upper flange 314 Rib 315 Taper 320 Air distribution nozzle 330 Return pipe 340 Lower steady rest mechanism 341 Holding beam 342 Receiving member 343 Fixture 344 Cylindrical body 345 Clamping piece 350 Upper steady rest mechanism 351 Projection piece 352 Concave groove 400 Rear heat transfer section 410 Heat exchanger tube group D Inner diameter d Inner diameter

Claims (7)

a casing in which particles separated by a cyclone and flowing down from a leg pipe of the cyclone are temporarily stored;
an inner cylinder arranged to introduce the particles into the casing, and whose lower part is buried inside the particles;
and a return pipe connected to the upper side surface of the casing and discharging particles, the loop seal inner cylinder support structure comprising:
a flange portion formed at the upper end of the inner cylinder;
an inner step part formed by expanding the inner diameter of the leg pipe of the cyclone so that the flange part is exposed and placed inside the leg pipe of the cyclone ;
Suspension reinforcing material disposed at an outer step formed between the outer periphery of the leg pipe and the outer periphery of the casing as the inner step is formed;
Loop seal inner cylinder support structure. The flange portion is
a lower flange placed on the inner step;
an upper flange disposed upwardly from the lower flange at a required interval;
The inner cylinder support structure for a loop seal according to claim 1 , further comprising ribs arranged radially from the center of the flange portion so as to connect the lower flange and the upper flange. The loop seal inner cylinder support structure according to claim 2 , wherein the lower flange is welded to the outer periphery of the inner cylinder, and the upper flange is welded to the outer periphery of the inner cylinder. 4. The inner cylinder support structure for a loop seal according to claim 2, further comprising a taper formed on the upper surface of the outer peripheral end of the lower flange so as to slope downward from the inner peripheral side to the outer peripheral side. a holding beam that extends from the inner surface of the casing of the loop seal toward the inner cylinder side and is arranged in multiple stages in the vertical direction;
The inner cylinder support structure for a loop seal according to any one of claims 1 to 4 , further comprising a receiving member provided on the inner cylinder so as to sandwich the holding beam from both sides in the circumferential direction. The inner part of the loop seal according to any one of claims 1 to 5 , wherein a guide weir is formed inside the leg pipe of the cyclone and is located above the flange part and has an inner diameter smaller than the inner diameter of the inner cylinder. Cylindrical support structure. The loop seal is provided in a circulating fluidized bed boiler equipped with a furnace that burns fuel and the cyclone that separates particles in combustion gas discharged from the furnace, and the return pipe is connected to the furnace. An inner cylinder support structure for a loop seal according to any one of claims 1 to 6 .

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