JPH03177704A - Removal of matter adhering to gas dispersion plate of fluidized bed device - Google Patents

Abstract

PURPOSE:To enable to wipe off matter such as the ash of combustion, etc. adhering to the inside of a gas dispersion pipe effectively by cooling rapidly the gas dispersion pipe by supplying a cooling medium to the outer face section of the gas dispersion pipe which is at high temperature of a gas dispersion plate. CONSTITUTION:When the pressure difference between the pressure on the upstream side and that of the downstream side of gas of the gas dispersion plates 5 and 6 is larger than a certain value which is larger than the pressure difference in the normal operation by a specified value, a signal is issued from a pressure difference meter 26 to a cooling water supply valve 25 and this valve is opened. Then, from a cooling water supply pipe 24a or 24b water of 50 deg.C used for water supply to a boiler is made to flow to the inside of a cooling water passage 24 of the gas dispersion plate 5 or 6, and a gas dispersion pipe 20 which is at 700 deg.C is cooled rapidly. With this arrange ment the gas dispersion pipe 20 is given a thermal shock and it contracts suddenly and an adhesion layer of the ash of combustion, etc. that adhere to the inner circumfer ential face of the pipe in the state of lamination is forcibly peeled off and it falls down to be removed from the gas dispersion pipe 20.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fluidized bed combustion apparatus that burns high water content residue such as beer grounds in a fluidized bed formed of a fluidized medium such as sand, and It relates to a method for removing deposits on a gas distribution plate of a fluidized bed device such as a fluidized bed boiler that burns t4 such as coal in a fluidized bed. The present invention relates to a method for removing deposits on a gas distribution plate of a fluidized bed apparatus, which allows such deposits to be effectively removed.

[Conventional technology]

For example, a fluidized bed combustion apparatus, which is a fluidized bed apparatus for fluidized combustion of highly water-containing residue such as beer dregs, has a configuration as schematically shown in FIG.

In Fig. 3, the fluidized bed combustion apparatus 1 has an air chamber 2 equipped with an air intake port 2a right and an auxiliary combustion burner 2b at the bottom, a primary fluid combustion chamber 3 at the middle stage, and a secondary fluid combustion chamber 4 at the top stage. Equipped and configured. A gas distribution plate 5.6 is provided across the device between the air chamber 2 and the primary flow combustion chamber 3, and between the -secondary flow combustion chamber 3 and the secondary flow combustion chamber 4. There is. - In the secondary flow combustion chamber 3, a fluid medium 7 such as sand having a particle size of, for example, 0.5 to 1 m is fluidized by the air supplied from the gas distribution plate 5 above the gas distribution plate 5 to flow into the primary combustion chamber 3. A bed 8 is formed, this fluidized bed 8
The high water content residue 12 is fed into the screw feeder feeder 13.
It is injected and burned. The gas distribution plate 5 is a partition plate 1 provided across the device, as shown in detail in FIG.
6, a large number of vertical gas dispersion vibes 14 and a horizontal water-cooled pipe 17 are attached to sandwich them. A gas dispersion cap 15 is attached to prevent the inflow and fall of the medium 7 and disperse the gas upward, and the gas dispersion vibrator 14 located slightly below the gas dispersion cap 15 has a plurality of vibrators disposed in the circumferential direction (for example, in the circumferential direction). Four gas ejection holes 14a are bored at equal intervals.

A refractory material 18 such as castable material having a predetermined thickness is attached to the lower part of the partition plate 16. In addition, - next flow combustion chamber 3
The gas distribution plate 6 between the combustion chamber 4 and the secondary flow combustion chamber 4 is also intercepted in the same manner as this gas distribution plate 5. - The upper space of the primary combustion fluidized bed 8 of the secondary fluid combustion chamber 3 is used as a primary combustion space 9.

On the other hand, in the secondary flow combustion chamber 4 in the upper stage of the secondary flow combustion chamber 3, the fluidized medium 7 is fluidized at the upper part of the gas distribution plate 6 by the combustion gas supplied from the gas jet hole 14a of the gas distribution vibe 14. - A secondary combustion fluidized bed 10 is formed, and the upper part thereof is the secondary combustion fluidized bed 1. Further, a water pipe 19 is installed in this secondary combustion fluidized bed. Note that this water pipe 19 should not be installed when the high moisture content residue 12 supplied to the secondary flow combustion chamber 3 contains extremely high moisture content or when the high moisture content residue 12 is a residue that is difficult to burn. There is also.

The operation of the fluidized bed combustion apparatus 1 having such a configuration will be explained.

The combustion gas from the auxiliary combustion burner 2b and the fluidizing/combustion air from the air intake port 2a of the air chamber 2 are introduced into the gas dispersion vibe 14 of the gas distribution plate 5, and the gas ejection hole 14a is introduced into the gas dispersion vibe 14 of the gas distribution plate 5.
A high water content residue 12 such as beer dregs containing 70% water is fed into the primary combustion fluidized bed 8 by a screw feeder 13. For example, approximately 70% of the residue 12 is burned in the secondary combustion fluidized bed 8 and the primary combustion space 9. Note that the temperature of the secondary combustion fluidized bed 8 is 750 to 850″C.
The high water content residue 12 put into this is kept at
is instantaneously evaporated by direct contact with the sand (fluidized medium 7), and the residue 12 which has lost moisture is easily combusted while being stirred by the sand. The remaining approximately 30% of unburned matter and ash generated in the primary flow combustion chamber 3 enter the gas dispersion vibe 14 of the upper gas distribution plate 6, and are further transferred to the secondary flow through the gas ejection holes 14a. The fluidized medium 7 is introduced into the combustion chamber 4, where it is fluidized to form a secondary combustion fluidized bed 10. The remaining approximately 30% of unburned matter is combusted in this secondary combustion fluidized bed 10 and the secondary combustion space 11 above it. and,
The heat retained in the combustion gas is absorbed by the water pipes 19 of the 10 parts of the secondary combustion fluidized bed, recovered as steam or hot water, and effectively utilized.

[Problems to be solved by the present invention]

In the fluidized bed combustion apparatus 1 for fluidized combustion of highly water-containing residue as shown in FIG. The unburned content and combustion ash generated in the combustion gas are introduced into the gas dispersion vibrator 14 of the gas dispersion plate 6 between the primary flow combustion chamber 3 and the secondary flow combustion chamber 4, and then the gas dispersion cap on the upper part thereof. The gas flows into the secondary flow combustion chamber 4 through the plurality of gas injection holes 14a below the gas dispersion vibrator 15, but in this process, as shown in FIG. The gas first collides with the lower surface of the gas dispersion cap 15 at the top of the gas dispersion vibrator 14, and then the gas flow is reversed and flows at high speed into the gas ejection hole 14a, which has a narrow opening area, and is discharged. The gas dispersion pipe 14 may have a complicated flow condition and may not be smooth, resulting in stagnation in the gas flow within the gas dispersion pipe 14.
Combustion ash adheres to the inner surface. This adhesion phenomenon gradually progresses as the operation continues, and the adhesion grows and accumulates until the gas distribution pipe 14 is blocked. Also, if the gas distribution pipe 14 becomes clogged,
The flow velocity in the gas distribution pipe 14 decreases and the gas distribution pipe 14
adhesion to the inner surface progresses. In addition,
Such adhesion of combustion ash is particularly noticeable when burning residues whose ash has a low melting point. When such adhesion to the inner surface of the gas distribution pipe 14 occurs, it becomes difficult for gas to be supplied from the primary flow combustion chamber 3 to the secondary flow combustion chamber 4 through the gas distribution plate 6, and the amount of gas to be supplied is reduced. There is a problem in that the differential pressure at the dispersion plate 6 becomes large, making it impossible to perform fluidized combustion. In addition, a large number of gas distribution pipes 14
When the adhesion state of combustion ash differs, there are places where gas flows easily and places where it is difficult to flow, and the pressure differs depending on the part of the fluidized bed, causing pressure fluctuations and making it difficult to perform fluidization in different ways. However, there is a problem in that efficient fluidized combustion cannot be performed.

The present invention has been made in view of these problems, and provides a gas dispersion device for a fluidized bed device that is capable of effectively removing deposits such as combustion ash adhering to the gas dispersion pipe attached to the gas dispersion plate. The purpose of this invention is to provide a method for removing deposits from a dispersion plate.

[Means to solve the problem]

In order to achieve the above object, the present invention (1) rapidly cools the gas distribution pipe by supplying a cooling medium to the outer surface of the gas distribution pipe which is in a high temperature state of the gas distribution plate. It is designed to remove any deposits that may have adhered to it.

(2) Detects the differential pressure between the gas upstream and downstream sides of the gas distribution plate, which has a large number of gas distribution pipes, and opens the cooling medium supply valve to supply the cooling medium when the differential pressure exceeds a certain value. By rapidly cooling the supplied gas dispersion pipe which is in a high temperature state, deposits adhering to the inner surface of the gas dispersion pipe are removed.

[For production]

When the outer surface of the gas distribution plate, which is at a high temperature of 700 to 800°C, is rapidly cooled with a cooling medium such as water or air at 20 to 50°C, the gas distribution pipe undergoes a thermal shock (
The gas dispersion pipe is subjected to a thermal shock, causing it to contract rapidly, and as the gas dispersion pipe contracts, an impact is applied to the adhering layer of combustion ash, etc. attached to the inner surface of the gas dispersion pipe, causing it to contract. , it is peeled off from the inner peripheral surface, shaken off, and dropped from the gas distribution pipe to be removed. Therefore, gas such as combustion gas flows smoothly through the gas dispersion pipe, and stable fluidization operation is performed. In addition, the differential pressure between the upstream and downstream sides of the gas distribution plate to which the gas distribution pipe is attached is detected, and the differential pressure exceeds a certain value that is a predetermined value greater than the differential pressure during normal operation. By occasionally supplying a cooling medium, even if the adhesion progresses to the inner surface of the gas dispersion pipe during operation, it can be reliably removed and the removal action can be performed automatically. can.

〔Example〕

Next, the present invention will be explained in detail based on the drawings. 1st
2 and 2 are an overall schematic longitudinal sectional view of a fluidized bed combustion apparatus to which the method of the present invention is applied, and an enlarged longitudinal sectional view of a gas distribution plate, respectively.

In both figures, the same parts and corresponding parts as in FIGS. 3 and 4 described above are given the same reference numerals, and their explanations will be omitted.

As shown in FIG. 1, the fluidized bed combustion apparatus l has a primary fluidized combustion chamber 3 located above an air chamber 2 with a gas distribution plate 5 interposed therebetween, and an upper part of the primary fluidized combustion chamber 3 for gas dispersion. A secondary flow combustion chamber 4 is located through the plate 6 . The air chamber 2 is provided with an air intake port 2a, an auxiliary combustion burner 2b, and an introduction port 2c for introducing a portion of combustion exhaust gas. A part of the combustion exhaust gas discharged from the secondary flow combustion chamber 4 and containing unburned matter and combustion ash is supplied to the combustion exhaust gas inlet 2C and is used to preheat combustion air in an air preheater (not shown). A pipe (not shown) for recycling and supplying the air to the air chamber 2 is connected. - A screw feeder 13 for supplying highly water-containing residue such as beer dregs is attached to the secondary flow combustion chamber 3.

The gas distribution plate 5 and the gas distribution plate 6 are provided with a gas differential pressure gauge 26 between the upstream side and the downstream side of each gas.
26 is installed. That is, for the gas distribution plate 5, a gas pressure outlet pipe 27b is connected to the side wall of the air chamber 2, and a gas pressure outlet pipe 27a is connected to the side wall of the secondary flow combustion chamber 3.
A differential pressure gauge 26 is installed between them. Also,
Also for the gas distribution plate 6, a gas pressure outlet pipe 27b is connected to the side wall of the primary flow combustion chamber 3, and a gas pressure outlet pipe 27a is connected to the side wall of the secondary flow combustion chamber 4, and a differential pressure gauge 26 is connected between them.
is installed. Cooling water supply pipes 28a and 18b, which serve as cooling medium supply pipes for rapidly cooling the gas dispersion vibe 20, are branched from the main supply pipe 28 and connected to each gas distribution plate 5.6. Also, a cooling water supply pipe 28a.

Cooling water supply valves (automatic valves) 25 and 25 as cooling medium supply valves are respectively installed in 28b.

The cooling water supply valve 25 and the differential pressure gauge 26 are connected by a cable for transmitting and receiving signals. Each gas distribution plate 5
．． Cooling water discharge pipes 29a and 29b are provided at the opposite end of the cooling water supply side of 6, respectively, and both are connected to the main discharge pipe 29.

On the other hand, the gas distribution plate 5.6 is constructed as shown in detail in FIG. Partition plates 23a separated by a predetermined distance above and below,
23b is attached across the device, and a plurality of cooling pipes 22 for cooling the gas distribution plate 5.6 itself are attached to each partition plate 23a, 23b. A space between the upper and lower partition plates 23a, 23b is formed as a cooling water passage 24 for rapidly cooling the gas distribution pipe 20, and cooling water supply pipes 28a, 28b are connected to the ends on the side walls thereof, respectively. The gas dispersion vibrator 20 is installed through the cooling water passage 24 with its top and bottom fixed to the upper and lower partition plates 23a and 23b, so that the outer circumferential surface of the gas dispersion vibe 20 is in direct contact with the cooling water. It is composed of A plurality of gas outlets 20a are formed in the upper part of the gas dispersion vibe 20 and the lower part of the gas dispersion cap 21. A refractory (insulating material) is attached to the lower surface of the lower partition plate 23b. The space between the upper part of the upper partition plate 23a and the gas outlet 20a of the gas dispersion vibrator 20 is a stationary part where the fluidizing medium 7 does not flow.

In a fluidized bed combustion apparatus having such a configuration, combustion gas from the auxiliary combustion burner 2b in the air chamber 2, air for fluidization and combustion from the air intake port 2a, and air discharged from the secondary fluidization combustion chamber 4 to the air preheater. After preheating the fluidizing and combustion air, a part of the mixed gas with the combustion exhaust gas from the combustion exhaust gas inlet 2c is recycled and introduced, and the gas portion is introduced into a large number of gas dispersion vibes 20 of the scattering plate 5. The gas is supplied from the gas outlet 20a into the primary fluid combustion chamber 3, and a primary combustion fluidized bed 8 is formed within the secondary fluid combustion chamber 3.

- Most (about 70%) of the highly water-containing residue 12 such as beer dregs is removed from the primary combustion fluidized bed 8 in the secondary fluidized combustion chamber 3 and is entrained in the combustion exhaust gas in the secondary fluidized combustion chamber 4. Unburned matter is burned. -The temperature of the next combustion fluidized bed 8 is 750
It is maintained at a high temperature of ~850°C, and the gas dispersion vibe 2
The temperature of the combustion chamber 3 is maintained at a slightly lower high temperature, for example, 700 to 800'' C, by the action of the cooling pipe 220.
ash) and unburned matter (unburnt carbon) here, each gas dispersion pipe 2 provided in a large number on the gas dispersion plate 6
0, and is distributed and supplied into the secondary flow combustion chamber 4 from the upper gas jet port 20a. Gas dispersion vibe 20
The combustion gas supplied into the secondary combustion fluidized chamber 4 fluidizes the fluidized medium 7 located above the gas jet port 20a of the gas dispersion vibrator 20 to form a secondary combustion fluidized bed 10. Unburned content (unburned content in the negative flow combustion chamber 3) is combusted. The temperature of this secondary combustion fluidized bed 10 is also 750 to 8
It is kept at a high temperature of 50"C, and the gas dispersion vibe 20"
The temperature of the cooling pipe 22 is maintained at a slightly lower high temperature, for example, 700 to 800'C. The combustion exhaust gas in the secondary flow combustion chamber 4 is discharged from the upper exhaust port and introduced into an air preheater (not shown), and preheats the fluidization and combustion air, and a portion of the combustion exhaust gas is preheated. is recycled to the air chamber 2, and the unburned content contained therein is again used for combustion in the combustion chamber 3. The gas distribution pipe 20 is made of heat-resistant and corrosion-resistant material, such as stainless steel.

As the operation continues, the gas distribution plate 5.
When deposits such as combustion ash adhere to the inner surface of the gas dispersion vibrator 20 of No. 6 and a ring-shaped layer is gradually formed on the inner peripheral surface as an adhesion product, the gas dispersion vibrator 2
The cross-sectional area of the passage in the air chamber 2 is reduced, the ventilation resistance is increased, and the differential pressure between the gas on the upstream side and the downstream side of the gas distribution plate 5.6, that is, the gas pressure in the air chamber 2 and the primary flow combustion chamber 3 is increased. Pressure difference,
Alternatively, the pressure difference between the gases in the secondary flow combustion chamber 3 and the secondary flow combustion chamber 4 becomes large. Then, the differential pressure is a constant value (for example, 50 to 100 H20) larger than the differential pressure during normal operation (for example, 500 to 600 marks H20).
Therefore, when the pressure exceeds, for example, 550 to 700 mmH, 0), the differential pressure gauge 26 detects the value. And differential pressure gauge 2
6 to the cooling water supply valve 25 and the supply valve 2
5 will be held. Then, water for boiler feed water having a temperature of 50°C is supplied from the cooling water supply pipe 24a or 24b to the cooling water passage 24 of the gas distribution plate 5 or 6 as a cooling medium.
The gas distribution pipe 20, which is in a high temperature state of 700° C., is rapidly cooled. Then, a thermal shock is applied to the gas distribution pipe 20 and the gas distribution pipe 20 is rapidly contracted, and attached N (adhesion products) such as combustion ash adheres to the inner peripheral surface of the gas distribution pipe 20 in an annular layer. Gas distribution pipe 20
As the radius of the gas distribution pipe 20 contracts, an impact is applied and the gas is contracted, and the gas distribution pipe 20 is forcibly peeled off from the inner circumferential surface, thrown off, and dropped from the gas distribution pipe 20 to be removed. A large number of gas dispersion pipes 2 have the action of removing such deposits.
This is done for 0. The cooling water used for quenching the gas distribution pipe 20 in the cooling water passage 24 of each gas distribution plate 5.6 is discharged to the cooling water discharge pipe 29a or 29b, respectively, and is merged into the main discharge pipe 29 and taken out. Used as boiler water supply.

Due to the action of removing deposits as described above, gas such as combustion gas flows smoothly through the gas distribution pipe 20 of each gas distribution plate 5.6, and the gas flows through each gas distribution pipe 20. The fluid is evenly supplied from the fluid to the primary and secondary fluid combustion chambers 3.4, thereby ensuring stable fluidization operation.

When the differential pressure between the upstream side and the downstream side of the gas distribution plate 5 or 6 falls below the predetermined value, a signal to close the cooling water supply valve 25 is issued from the differential pressure gauge 26, the supply valve is closed, and the cooling water is The supply of cooling water to the passage 24 is cut off. below,
Such a rapid cooling operation of the gas distribution pipe 20 using cooling water is repeated intermittently to remove deposits.

Note that the operation of removing the deposits from the gas distribution pipes 20 on the upper and lower gas distribution plates 5.6 is performed independently for each gas distribution plate. The frequency is higher in the upper gas distribution plate 6 through which more combustion ash passes.

In this way, in this embodiment, the differential pressure between the gas upstream side and the downstream side of the gas distribution plate 20 is detected, and cooling water is supplied when the differential pressure exceeds a certain value, so that the operation Even when adhesion progresses to the inner surface of the gas dispersion vibrator 20 due to
The brushing off is performed reliably, and the brushing off action is automatically performed.

In the above embodiment, the case where the lower gas distribution plate 5 is also used to remove deposits is shown. This action is not necessary, and the upper gas distribution plate 6
You only need to do this for

Further, in the above embodiments, water for boiler feed water was used as the cooling medium, but room temperature air (20 to 30°C) may be used instead. In this case, the air used to rapidly cool the gas distribution pipe 20 is effectively used as fluidization and combustion air.

In the above embodiments, the fluidized bed apparatus handles the highly water-containing residue 1.
2 is shown as a fluidized bed combustion apparatus for fluidized combustion (incineration), but in the present invention, the fluidized bed apparatus
A solid or liquid fuel such as coal is supplied as fuel in the combustion chamber 3, and a boiler tube that comes into contact with the fluidized bed is installed in this secondary fluidized combustion chamber 3, and the boiler tube absorbs the combustion heat of the fuel from the fluidized bed. On the other hand, the secondary fluid combustion chamber 4 is a desulfurization chamber using a desulfurizing agent such as limestone as a fluidized medium, and the flue gas in the secondary fluid combustion chamber 3 is desulfurized. It can also be applied to boilers.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is possible to forcibly shake off the adhered products in the gas dispersion plate by applying an impact through the gas dispersion plate of the fluidized bed apparatus. This allows the gas to flow smoothly inside the gas dispersion vibrator, eliminates pressure fluctuations on the gas dispersion plate, and allows stable fluidization operation to continue.In addition, the gas upstream side of the gas dispersion plate If the differential pressure between the downstream side and the downstream side is detected and the cooling medium is supplied when the differential pressure exceeds a certain value, it is possible to ensure that the adhered products inside the gas dispersion vibrator are removed, and the The action can be performed automatically, and stable fluidization operation can be continued.

[Brief explanation of drawings]

1 and 2 show an embodiment of a fluidized bed combustion apparatus to which the method of the present invention is applied. FIG. 3 is a vertical cross-sectional view schematically showing a fluidized bed combustion apparatus as a conventional fluidized bed apparatus, and FIG. 4 is a partial enlarged vertical cross-sectional view of the gas distribution plate of FIG. 3. 1...Fluidized bed combustion device, 2...Air chamber, 3...-
Secondary flow combustion chamber, 4... Secondary flow combustion chamber, 5.6...
Gas distribution plate, 7... Fluidized medium, 8... Secondary combustion fluidized bed, 10... Secondary combustion fluidized bed, 23a123b...
Partition plate, 17. 22... Water cooling pipe, 20... Gas distribution pipe, 24... Cooling water (cooling medium) passage, 25...
- Cooling water supply valve, 26... Differential pressure gauge, 28... Cooling water main supply pipe, 29... Cooling water main discharge pipe.

Claims (2)

[Claims] (1) The gas distribution plate of a fluidized bed device is installed across the fluidization chamber and has a large number of gas distribution pipes, and each gas distribution pipe injects gas into the fluidization chamber to fluidize the fluidized medium. This is a method for removing deposits, in which a cooling medium is supplied to the outer surface of the gas distribution pipe that is in a high temperature state on the gas distribution plate to rapidly cool the gas distribution pipe, thereby removing deposits that have adhered to the inner surface of the gas distribution pipe. A method for removing deposits on a gas distribution plate of a fluidized bed apparatus, characterized in that: (2) Detects the differential pressure between the gas upstream and downstream sides of the gas distribution plate, which has a large number of gas distribution pipes, and opens the cooling medium supply valve to supply cooling medium when the differential pressure exceeds a certain value. Attaching the fluidized bed apparatus to the gas distribution plate according to claim (1), characterized in that deposits adhering to the inner surface of the gas distribution pipe are removed by rapidly cooling the gas distribution pipe in a high temperature state. How to remove kimono.