JPH0590108U - Fluidized bed boiler - Google Patents

Abstract

(57) [Summary] [Purpose] To reliably prevent the phenomenon that sand, which is a fluid medium, flows back into the lower chamber through the air dispersion pipe. [Structure] The upper end portion of the main pipe 30c of the dispersion pipe 30 is a disc 30
a at the upper end of the main pipe 30c with a space between the disc 30a of the main pipe and an upper opening 30e.
The inner pipe 30b and the main pipe 30c are provided by forming the inner pipe 30b
And an annular space portion 30g is formed between
The lower end portion of g is configured such that the diameter gradually increases from the upper side to the lower side of the peripheral wall of the inner pipe lower end portion 30d to form the main pipe 30c.
The inner pipe is closed at a position lower than the upper end opening 30e of the inner pipe and at the lower end of the inner pipe by forming a smooth curve having a predetermined radius of curvature R toward the side and joining the main pipe 30c. A plurality of air blowing holes 30f communicating with the annular space were provided in the circumferential direction of the main pipe at the same height position as the upper surface S of the inner pipe at the junction with the main pipe.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention supplies coal to a fluidized combustion chamber where sand flows and burns it, heats water in a heat transfer tube to generate steam, and desulfurizes the gas after burning with a desulfurizing agent and discharges it to the outside. It concerns a fluidized bed boiler.

[0002]

[Prior Art]

 In recent years, a fluidized bed boiler has been developed as a boiler with high combustion efficiency and less waste gas pollution. This type of fluidized bed boiler is equipped with three chambers, a storage chamber, a combustion chamber, and a desulfurization chamber, which are separated in order from the bottom in the boiler body. The sand stored in the chamber is made to flow by blowing air, and the coal supplied to the combustion chamber is burned while flowing along with the sand.The heat transfer tube of the combustion chamber makes contact with this combustion gas and heated fluid medium. Steam is generated by heating the water that is heated by the heat exchanger and passes through the heat transfer tube. Then, the combustion gas is desulfurized with a desulfurizing agent such as limestone in the desulfurization chamber and exhausted, and unburned carbon is captured and burned in the desulfurization chamber.

[0003]

[Problems to be solved by the device]

 This type of fluidized bed boiler is provided with a plurality of cylindrical dispersion pipes, and the fluidizing air blown up from below is dispersed in each direction and supplied evenly to the fluidized bed and desulfurized bed. Is being done. However, in the conventional dispersion pipe, sand as a fluid medium and apatite as a desulfurizing agent flow back into the lower chamber through the dispersion pipe due to pressure fluctuations of the blown air, and especially fuel supply. When air is transported directly above the dispersion pipe, the flow medium flows backward due to the blowing of air and the combustion of volatiles, and it easily falls from the holes in the dispersion pipe, which deteriorates the flow state and the desulfurization state. Not only does it become stable, but the fluid medium and desulfurizing agent that have fallen back and dropped must be collected and replenished, which poses the problem of increased labor and increased equipment costs for the recovery device. It was

[0004]

[Means for Solving the Problems]

 In order to solve such a problem, in the present invention, a plurality of partition plates are provided between the upper and lower chambers, and air is introduced from the lower chamber through the lower part of the main pipe and the air is introduced from the upper chamber to the upper chamber. A dispersion pipe for air dispersion to be blown out, in which the upper end of the main pipe of the dispersion pipe is closed, and the upper end of the main pipe is spaced apart from the upper end closing part of the main pipe facing the upper chamber. An inner pipe opened upward is provided to form an annular space portion between the inner pipe and the main pipe, and a lower end portion of the annular space portion is hung on the peripheral wall of the inner pipe lower end from above. The inner diameter of the inner pipe is closed at a position lower than the upper end opening of the inner pipe and at the lower end of the inner pipe. At the same height as the upper surface of the inner pipe at the junction of the It has a structure in which a plurality of air outlet holes communicating with between.

[0005]

[Action]

 The air introduced from the lower chamber into the main pipe from the lower end of the main pipe of the dispersion pipe rises inside the main pipe and passes through the inner pipe located in the upper part facing the upper chamber of the main pipe, and the open end above it. It is discharged from the pipe, collides with the upper end closed part of the main pipe, turns over, descends into the annular space between the inner pipe and the main pipe, and jets into the upper chamber from multiple air blowing holes of the main pipe. Are dispersed. Even if the fluidized medium in the upper chamber may enter the annular space inside the main pipe from the air blowout hole of the main pipe, the inside of the inner pipe is opened from the opening at the upper end of the inner pipe that is higher than the air blowout hole. It never invades and flows backwards.

However, since the air blowing holes of the main pipe are formed as holes scattered around the main pipe, the inflow of the flowing medium is prevented as much as possible. When the fluidized medium flows in, it accumulates at the lower end of the annular space, and when it advances and becomes higher than the air blowing hole, it will overflow the air blowing hole and flow out of the main pipe. And In this case, the accumulated portion is joined to the main pipe by forming a smooth curve toward the main pipe with the diameter of the peripheral wall at the lower end of the inner pipe gradually increasing from the upper side to the lower side. Since the air blowing hole is located at the same height as the upper surface of the inner pipe at this joint, the fluidized medium that has accumulated and becomes heavier has a smooth curved line. Since the peripheral wall at the lower end of the inner pipe has a small slip resistance, the air flow flowing down the annular space and toward the air blowing hole also creates a smooth curved peripheral wall at the lower end of the inner pipe. As it slides down along the surface and is pushed away, it tries to flow out from the air blowing hole to the outside upper chamber as it is, so the flow out of the main pipe is extremely smooth. Therefore, even if the fluidized medium flows into the main pipe, the backflow into the inner pipe is reliably prevented. Further, the diameter of the peripheral wall of the lower end of the inner pipe is gradually increased from the upper side to the lower side as described above, and a smooth curve is formed toward the main pipe side so that the inner wall is connected to the main pipe. Air smoothly flows into the pipe.

[0007]

【Example】

 Next, embodiments of the present invention will be described in detail with reference to the drawings. 1 and 2 show an embodiment of a fluidized bed boiler according to the present invention. FIG. 1 is a longitudinal sectional view of a dispersion pipe, and FIG. 2 is a longitudinal sectional view of a fluidized bed boiler. In the figure, a main body 1 of a fluidized bed boiler is formed into a rectangular box shape surrounded by water cooling walls 2 in which a plurality of water cooling pipes (not shown) are embedded, and is formed in a rectangular box shape. An air chamber 7, a storage chamber 8, a combustion chamber 9, and a desulfurization chamber 10 are partitioned in order from the bottom by the partition plates 4, 5 and 6 containing 3 pieces. The air chamber 7 and the storage chamber 8 are provided with an air-transporting type coal supply pipe 13 connected between a coal supply hopper (not shown) via a dryer and a crusher, and the Is being supplied.

Further, in the desulfurization chamber 10, an air-transporting limestone transport pipe 14 connected to a limestone supply hopper (not shown) is engaged, and a predetermined amount of limestone 15 is constantly provided in the desulfurization chamber 10. Are supplied so that they can be stored. Reference numeral 16 denotes a heat transfer tube which is curved and installed so as to reciprocate in the combustion chamber 9 in a zigzag manner. A water supply pipe 17 connected to one end of the heat transfer pipe is connected to a circulation pump and also connected to the other end. The supply pipe 18 is connected to a steam use facility. In this embodiment, a bypass connecting the water supply pipe 17 and the supply pipe 18 is provided to serve as a heat transfer tube for a separately provided exhaust heat utilization boiler. Reference numeral 30 is a distributor provided as a plurality on each of the partition plates 4, 5 and 6, and serving as a dispersion pipe that blows the blown air into the upper chamber in sequence while uniformly distributing the blown air. It will be explained based on.

The distributor 30 is formed in a tubular shape in which the upper end of the main pipe 30c is closed by a disc 30a, and the upper part of the inner portion of the main pipe 30c facing the upper chamber has a circular shape at the upper end of the main pipe 30c. An inner pipe 30b having an opening 30e with an upper end facing upward is provided at an interval from the lower surface of the plate 30a, and an annular space 30g is formed between the main pipe 30c and the inner pipe 30b. .. Then, the lower end portion of the annular space 30g forms a smooth curve with a predetermined radius of curvature R toward the main pipe 30c so that the diameter of the peripheral wall of the lower end portion 30d of the inner pipe 30b gradually increases from the upper side to the lower side. It is formed and joined to the inner wall surface of the main pipe 30c to be closed. The main pipe 30c has a height lower than the upper end opening 30e of the inner pipe 30b and the same height as the upper surface S of the inner pipe 30b at the joining point of the lower end 30d of the inner pipe 30b to the main pipe 30c. An air blowing hole 30f communicating with the annular space 30g is laterally provided at the position. A plurality of air outlet holes 30f are provided in the circumferential direction of the main pipe 30c.

Further, sand 20 as a fluid medium having a diameter of about 1.6 mm is stored in the storage chamber 8, and the same sand 20 is stored in the combustion chamber 9 as well. Reference numerals 21 and 22 denote upper and downcomers for the sand 20, which are provided to connect the storage chamber 8 and the combustion chamber 9, respectively, and the sand 20 is placed between the chambers 8 and 9 manually or by a level detection by a sensor. The amount of sand 20 in the combustion chamber 9 is constantly kept constant. On the other hand, a discharge port 23 for discharging combustion gas is provided at the upper end of the desulfurization chamber 10, and is connected to a chimney via the exhaust heat utilization boiler by a duct. Reference numeral 24 is a discharge port that is opened in the desulfurization chamber 10 and causes the limestone 15 to overflow and to be extracted to the outside.

The operation of the fluidized bed boiler configured as described above will be described. When coal is supplied from the coal supply pipe 13 to the layer of sand 20 stored in the combustion chamber 10 and air is sent to the air chamber 7 and the storage chamber 8, when the preheated coal is ignited by a burner or the like, it is burned. Coal is burned by the supply of air, and this combustion is promoted by the flow of the air blown up from the distributor 30 between the sand 20 and the coal, resulting in efficient combustion. This combustion heats the water in the heat transfer tube 16 to generate steam, which is supplied to the steam using facility. On the other hand, the combustion gas enters the desulfurization chamber 10 through the distributor 30 above the combustion chamber 9, and the sulfur content is removed to become harmless gas, which is discharged from the discharge port 23, and unburned carbon is captured in the desulfurization chamber 10. Is burned. The combustion gas discharged from the discharge port 23 raises the temperature of steam flowing from the supply pipe 18 to the steam use facility when passing through a separately provided boiler, and then is discharged from the chimney. After the desulfurization reaction, the limestone 15 in the desulfurization chamber 10 overflows from the outlet 24 and is discharged to a limestone storage tank or the like.

In such a fluidized bed boiler, since the distributor 30 is configured as described above, the air blown into the inside of the main pipe 30c of the distributor 30 from the lower chamber does not flow inside the main pipe 30c. And flows into the inner pipe 30b located in the upper portion of the main pipe 30c facing the upper chamber. At this time, the lower end portion 30d of the inner pipe 30b is gradually increased in diameter from the upper side to the lower side as described above and is formed in a smooth curve toward the main pipe 30c side. The air has a low flow resistance and flows in smoothly. Then, the air is discharged from the opening 30e at the upper end of the inner pipe 30b, collides with the lower surface of the disc 30a at the upper end of the main pipe 30c, and is inverted, and enters the annular space 30g between the inner pipe 30b and the main pipe 30c. It flows in, descends, and is jetted into the upper chamber without difficulty from a plurality of air blowing holes 30f of the main pipe 30c to be dispersed. Therefore, the sand 20 and the limestone 15 can be in a stable fluidized state, and uniform combustion and desulfurization are performed.

The sand 20 and the limestone 15, which are fluid media in the upper chamber, may enter the annular space 30g inside the main pipe 30c through the air outlet holes 30f of the main pipe 30c. The opening 30e at the upper end of the inner pipe at a position higher than the hole 30f does not enter the inner pipe 30b and flow backward. Since the air blowing holes 30f of the main pipe 30c are formed as holes scattered in the periphery, the inflow of, for example, sand 20 as a fluid medium is prevented as much as possible. Then, when the sand 20 flows in, it accumulates on the lower end portion 30d of the annular space 30g, and when it advances and the height becomes higher than the air blowing hole 30f, the air blowing hole 30f overflows and the main pipe. Trying to flow out of 30c.

At this time, in the accumulated portion, the diameter of the lower end portion 30d of the inner pipe 30b is gradually increased from the upper side to the lower side, and a smooth curve having a radius of curvature R toward the main pipe 30c side is formed. It is joined to the main pipe 30c and the air blowing hole 30f is located at the same height position as the upper surface S of the inner pipe 30b at this joining point. The sand 20 flows downward toward the air blowing hole 30f in the annular space 30g because the peripheral wall of the lower end portion 30d of the inner pipe 30b having the smooth curve has a small slip resistance. Due to the air flow, it slides downward along the wall surface formed by this smooth curve and is pushed away, and it tries to flow out from the air blowing hole 30f to the outside upper chamber as it is. Outflow to the outside of 0c is extremely smooth. Therefore, even if the sand 20 flows into the main pipe 30c, the backflow to the inner pipe 30b can be reliably prevented. The same is true for limestone 15.

[0015]

[Effect of the device]

 As is clear from the above description, according to the present invention, in the fluidized bed boiler, the air blown into the dispersion pipe from the bottom is expanded to the inner pipe from the lower end to the lower end. From the upper end opening of the inner pipe through the annular space and is blown up into the upper chamber from multiple air outlets around the main pipe, which not only impairs the original function of the dispersion pipe, but also the upper chamber. Even if the fluid medium and the desulfurizing agent in the main pipe enter the annular space inside the main pipe through the air blow-out hole of the main pipe, the opening at the upper end of the inner pipe is at a position higher than the air blowing hole. Invasion into the inner pipe and backflow can be prevented.

In particular, in the present invention, since the air blowing holes of the main pipe are formed as holes scattered in the circumferential direction, it is possible to originally prevent the inflow of the flowing medium as much as possible. Even if the flowing medium flows into the annular space, the structure of the part where it flows in and accumulates is as specified, and the flowing medium moves down the annular space to the air blowout hole. With the help of the air flow that flows toward it, it is configured so that it is naturally pushed downward by its own weight and discharged to the outside, so the flowing medium outside the main pipe can be made to flow extremely smoothly. Therefore, even if the fluidized medium flows into the main pipe, the backflow into the inner pipe can be more reliably prevented. For this reason, there is no need to collect and replenish the flowing medium that has flowed back into the lower chamber, which reduces labor and saves equipment costs by eliminating the need for a recovery device. Boiler operation rate is improved for those that are recovered dynamically.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a dispersion tube of the present invention.

FIG. 2 is a longitudinal sectional view showing an embodiment of the fluidized bed boiler of the present invention.

[Explanation of symbols]

 1 Fluidized bed boiler main body 4, 5 and 6 Partition plate 7 Air chamber 8 Storage chamber 9 Combustion chamber 10 Desulfurization chamber 15 Limestone 20 Sand 30 Distributor (dispersion pipe) 30a Disk 30b Inner pipe 30c Main pipe 30d Inner pipe lower end 30e Inside Tube opening 30f Air blowing hole 30g Annular space R Inner tube lower end curvature radius S Upper surface

Claims (1)

[Scope of utility model registration request] 1. A plurality of partition plates are provided between the upper and lower chambers,
A dispersion pipe for air dispersion, in which air is introduced from the lower chamber through the lower part of the main pipe and blows the air from the upper part to the upper chamber, the upper end of the main pipe of the dispersion pipe is closed, and the upper part of the main pipe is closed. Inside the upper portion facing the chamber, an inner pipe having an upper end opened upward with a gap from the upper end closing portion of the main pipe is provided to form an annular space portion between the inner pipe and the main pipe, The lower end portion of the annular space portion is joined to the main pipe by forming a smooth curve toward the main pipe with the diameter of the peripheral wall of the lower end portion of the inner pipe gradually increasing from the upper side to the lower side. Closed at a position lower than the upper end opening of the inner pipe, and at a height position equivalent to the upper surface of the inner pipe at the junction of the lower end of the inner pipe to the main pipe, in the circumferential direction of the main pipe. A fluidized bed boiler comprising a plurality of air blowing holes communicating with the annular space.