JPH0518563Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] This invention supplies coal into a fluidized combustion chamber in which sand flows, burns it, heats the water in the heat transfer tube to generate steam, and after the combustion This relates to a fluidized bed boiler that desulfurizes the gas using a desulfurizing agent and discharges it to the outside.

[Conventional technology]

In recent years, fluidized bed boilers have been developed as boilers with high combustion efficiency and low 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 combustion chamber is made to flow by blowing air, and the coal supplied to the combustion chamber is combusted while flowing with the sand. Steam is generated by heating. 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.

[Problem that the invention attempts to solve]

This type of fluidized bed boiler is equipped with a plurality of cylindrical dispersion pipes, which disperse the fluidizing air blown up from below in each direction and evenly supply it to the fluidized bed and desulfurization layer. things are being done. However, in conventional dispersion pipes, sand as a fluidizing medium and limestone as a desulfurizing agent flow back through the dispersion pipe to the lower chamber due to pressure fluctuations in the blown air, etc., especially when supplying fuel. When this is carried out by pneumatic transportation just above the dispersion tube, the fluidized medium tends to flow backwards and fall through the holes of the dispersion tube due to the air blowout and combustion of volatile matter.
Not only will the fluidization condition deteriorate and the desulfurization condition become unstable, but the fluidization medium and desulfurization agent that have flowed back and fallen must be recovered and replenished, which increases the labor burden and reduces the capacity of the recovery equipment. There was a problem that the cost of equipment for this purpose was high.

[Means for solving the problem]

In order to solve these problems, the fluidized bed boiler according to the present invention has a plurality of dispersion pipes for blowing up air dispersion provided between the upper and lower chambers, and the upper end facing the upper chamber is a double pipe. The structure is formed into a tubular shape with its upper end closed, and the bottom plate closes the lower end of the annular space between the inner tube and the outer tube of the double tube, and the upper end of the annular space is placed at the upper end of the inner tube. A plurality of air outlet holes are provided in the outer pipe portion near the upper part of the bottom plate which is lower than these communication holes and at a position offset in the circumferential direction from each communication hole. It has been established.

[Effect]

According to the present invention, air blown from the lower chamber through the opening at the lower end of the dispersion tube rises inside the inner tube, and passes through the plurality of communication holes at the upper end of the inner tube to the upper end of the annular space between the inner tube and the outer tube. The air flows into the side, passes through the annular space, and is blown up and dispersed into the upper chamber through a plurality of blow-off holes that are bored in the outer tube at the lower end side, offset from the communication hole in the circumferential direction. . Although the fluid medium in the upper chamber may enter the annular space through the plurality of outlet holes in the outer tube, the inner tube is formed at a higher position than the outlet holes and offset in the circumferential direction. Intrusion into the inner tube through the plurality of communication holes at the upper end of the tube can be prevented, thereby reliably preventing the backflow of the fluid medium from the upper chamber to the lower chamber as in the conventional case.

〔Example〕

1 to 3 show an embodiment of a fluidized bed boiler according to the present invention, and FIG. 1 is a longitudinal cross-sectional view of a dispersion tube;
FIG. 2 is a cross-sectional view along AA of FIG. 1, and FIG. 3 is a vertical cross-sectional view of the fluidized bed boiler.

In the figure, the main body 1 of the fluidized bed boiler is formed into a rectangular box shape surrounded on four sides by water-cooled walls 2 in which a plurality of water-cooled pipes (not shown) are buried. An air chamber 7, a storage chamber 8, a combustion chamber 9, and a desulfurization chamber 10 are separated from each other in order from the bottom by partition plates 4, 5, and 6 containing water-cooled pipes 3. Air pipes 11 and 12 connected to an unillustrated blower are inserted into the air chamber 7 and the storage chamber 8, respectively, and air is blown into the combustion chamber 9. A pneumatic coal supply pipe 13 connected to the hopper via a dryer and a crusher is inserted to supply coal. moreover,
A pneumatic limestone transport pipe 14 is connected to the desulfurization chamber 10 and a limestone supply hopper (not shown).
A predetermined amount of limestone 15 is always stored in the desulfurization chamber 10. 1
6 is a heat transfer pipe installed in a curved manner so as to reciprocate in a staggered manner within the combustion chamber 9, and a water pipe 17 connected to one end thereof is connected to a circulation pump, and is connected to the other end. The supplied supply pipe 18 is connected to steam-using equipment. In this embodiment, a bypass is provided that connects the water pipe 17 and the supply pipe 18 midway, and serves as a heat transfer tube of a separately provided waste heat utilization boiler. Reference numeral 19 denotes a distributor, which is a dispersion pipe that is provided in plural pieces on each of the partition plates 4, 5, and 6, and blows the blown air into the upper chamber while uniformly distributing it. This will be explained based on FIG. The distributor 19 has an upper end connected to a disk 19.
It is formed into a tubular shape closed by a, and its upper end facing the upper chamber is divided into two parts, an inner pipe 19b and an outer pipe 19c.
It has a heavy pipe structure. Inner tube 19b and outer tube 19c
The lower end of the annular space between the two is closed by a bottom plate 19d. A plurality of holes 19e are provided at the upper end of the inner tube 19b as communication holes for communicating between the inside and outside, and a plurality of holes 19e are provided at the lower end of the outer tube 19c as blow-off holes to the upper chamber. 19f is the inner pipe 19
It is provided at a lower position than the hole 19e of b. The air blown from the lower open end of the inner tube 19b blows up inside the inner tube 19b, enters the upper end side of the annular space between the inner and outer tubes through the hole 19e, passes through the annular space, and reaches the lower end thereof. It is blown out from the side hole 19f. Here, in the double pipe portion on the upper end side of this distributor 19, the inner pipe 19b and the outer pipe 1
The plurality of holes 19e as communication holes communicating with the upper end of the annular space by the outer tube 19c and the plurality of holes 19f as blowing holes communicating the annular space and the upper chamber at the lower end of the outer tube 19c are the first As is clear from the drawings and FIG. 2, they are formed to be offset in the height direction and also to be offset in the circumferential direction. Therefore, sand 20 and the like as a fluid medium, which will be described later, flows from the upper chamber outside the outer tube 19c into the hole 19.
Even if it flows into the annular space from f, the inner pipe 1
The holes 19e on the 9b side are offset from these holes 19f in the circumferential direction and are formed above the holes 19f, so that the sand 20 etc. that flowed into the annular space from the holes 19f do not flow into the annular space. Since the sand 20 and the like cannot reach the hole 19e of the inner tube 19b unless the direction is changed by hitting the wall surface of the tube 19b and lifted further upward, the sand 20 and the like cannot reach the hole 19e of the inner tube 19b, 19
It is stored in the annular space between the inner tube 19b and prevented from flowing into the inner tube 19b through the hole 19e on the inner tube 19b side.

Furthermore, sand 20 as a fluid medium having a diameter of about 1.6 mm is stored in the storage chamber 8.
Also, the same sand 20 is stored in the combustion chamber 9 below the supplied coal. Reference numerals 21 and 22 indicate an upcomer and a downcomer for the sand 20, which are provided in communication with the storage chamber 8 and the combustion chamber 9, respectively.The sand 20 is transferred to both chambers 8, 9 manually or by level detection using a sensor. The combustion chamber 9
It is constructed so that the amount of sand 20 inside is kept constant at all times. On the other hand, an exhaust port 23 for discharging combustion gas is provided at the upper end of the desulfurization chamber 10, and is connected to the chimney via the exhaust heat utilization boiler via a duct. Reference numeral 24 denotes an extraction port that opens into the desulfurization chamber 10 and allows the limestone 15 to overflow and be extracted to the outside.

The operation of the fluidized bed boiler configured as above will be explained. After supplying coal to the upper layer of sand 20 stored in the combustion chamber 9 and sending air to the air chamber 7 and storage chamber 8, when the coal preheated with a burner etc. is ignited, the combustion air is supplied. Then, the coal burns, and this combustion is promoted by the flow of the sand 20 and the coal by the air blown up from the distributor 19, resulting in efficient combustion. This combustion heats the water in the heat transfer tube 16 to generate steam, which is supplied to steam-using equipment. On the other hand, the combustion gas enters the desulfurization chamber 10 via the distributor 19, the sulfur content is removed, the gas becomes harmless, and it is discharged from the exhaust port 23, while carbon is captured and burned in the desulfurization chamber 10. . Discharge port 23
When the combustion gas discharged from the pipe passes through a separately provided boiler, it heats up the steam headed from the supply pipe 18 to the steam usage equipment, and then is discharged from the chimney.
Moreover, the limestone 15 in the desulfurization chamber 10 overflows from the extraction port 24 after the desulfurization reaction and is discharged to a limestone storage tank or the like.

In combustion in such a fluidized bed boiler, the fluidized state is stabilized and uniform desulfurization is performed by the dispersion effect of the air blown up inside each distributor 19 as described above. The upper part of the tributator 19 has a double pipe structure to form an annular space closed by a disc 19a at the upper end and a bottom plate 19d, and the inner pipe 19b and the outer pipe 19c are arranged at different levels vertically and in the circumferential direction. By providing the holes 19e and 19f that are misaligned, air flows through the inner tube 19, as is clear from FIGS. 1 and 2.
The sand 20 and limestone 15 in the upper chamber do not flow back into the lower chamber. For example, sand 20 is
Sand 20 may enter the annular space through the hole 19f of the hole 9c, but this sand 20 accumulates on the bottom plate 19d, and when it exceeds the hole 19f, it overflows from the hole 19f, so that it is higher than the hole 19f and in the circumferential direction. The inner tube 19b is inserted from the hole 19e located at a position shifted from the
There is no backflow inward. The same applies to limestone 15.

[Effect of idea]

As is clear from the above description, according to the fluidized bed boiler according to the present invention, the plurality of dispersion pipes for blowing up air dispersion provided between the two upper and lower chambers are arranged such that the upper end portion facing the upper chamber is a double pipe. The structure is formed into a tubular shape with its upper end closed, and the lower end side of the annular space between the inner tube and the outer tube of the double tube is closed with a bottom plate,
The upper end of the inner tube is provided with a plurality of communication holes that communicate with the upper end of the annular space, and the outer tube portion is located close to the top of the bottom plate and is lower than these communication holes, and is connected to each communication hole in the circumferential direction. Since a plurality of blow-off holes are provided at offset positions, the air blown into the dispersion tube from the lower chamber flows through the annular space of the double tube section through the plurality of communication holes on the upper end side of the inner tube. The air is then blown up into the upper chamber from a plurality of blow-off holes located below the communication hole and offset in the circumferential direction, and not only can the original effect of the dispersion tube be exerted, but also the air inside the upper chamber can be Fluid media and desulfurization agents are
Although the plurality of blow-off holes on the outer tube side may enter the annular space and deposit on the bottom plate, the inner tube is formed at a higher position than the blow-off holes of the outer tube and is shifted in the circumferential direction. It is possible to reliably prevent the fluid from flowing backward into the inner tube through the multiple communication holes on the upper end side and falling down. This eliminates the need to collect and replenish the flowing medium that has flowed back into the lower chamber, which saves labor. In addition, there are various excellent practical effects, such as reducing equipment costs because there is no need to provide a recovery device, and improving the operating rate of the boiler in the case where combustion is interrupted and recovery is performed manually.

[Brief explanation of the drawing]

1 to 3 show an embodiment of a fluidized bed boiler according to the present invention, and FIG. 1 is a longitudinal cross-sectional view of a dispersion tube;
FIG. 2 is a cross-sectional view along AA of FIG. 1, and FIG. 3 is a vertical cross-sectional view of the fluidized bed boiler. 4, 5, 6... Partition plate, 7... Air chamber, 8...
Storage chamber, 9... Combustion chamber, 10... Desulfurization chamber, 15...
... Limestone, 17 ... Air pipe, 19 ... Distributor, 19a ... Disk, 19b ... Inner pipe, 1
9c...Outer tube, 19d...Bottom plate, 19e, 19f
...hole.

Claims (1)

[Scope of utility model registration request] A plurality of dispersion tubes for blowing up air dispersion provided on a partition plate between two upper and lower chambers are formed into a tubular shape in which the upper end portion facing the upper chamber has a double tube structure and the upper end portion is closed. The lower end of the annular space between the inner and outer pipes of the heavy pipe is closed off with a bottom plate, and the upper end of the inner pipe is provided with a plurality of communication holes that communicate with the upper end of the annular space. A fluidized bed boiler characterized in that a plurality of blow-off holes are provided in a portion of the outer tube close to the top of the bottom plate which is lower than the communication holes and at a position shifted in the circumferential direction from each communication hole.