JP2898198B2 - Fluid bed furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a low-speed bed for mixing a material to be burned with a layer material to dry and pyrolyze the material, and a high-speed bed for burning the material to be burned sent from the low-speed bed. The present invention relates to a high-speed circulation type fluidized-bed furnace for circulating a layer material at a high speed to burn an object to be burned.

[0002]

2. Description of the Related Art In recent years, for refuse incinerators for incinerating municipal solid waste and industrial waste, the incineration method using a stoker furnace has generally become widespread, but due to the tightening of emission regulations for carbon monoxide and dioxin. However, the incineration method using a fluidized bed furnace is becoming widespread. For example, a high-speed circulating fluidized bed incinerator that circulates bed material in the vertical direction can be used for wood chips, bark,
It was developed for the purpose of incinerating industrial waste such as waste tires. Its features are that the hearth load is as high as 3 to 5 times that of a general fluidized bed furnace, and the inner circulating bed material is To cover the incinerated material, harmful volatiles generated from the incinerated material are not blown up before combustion,
Accordingly, the generation of carbon monoxide, nitrogen oxides, dioxin, and the like can be suppressed, and it can be said that the incinerator is a low-pollution type incinerator that can be formed extremely compactly compared with other types of incinerators currently in operation.

For example, this high-speed circulating fluidized bed incinerator proposed in FIG. 4 of JP-A-64-46511 discloses a high-speed circulating fluidized-bed incinerator, as shown in FIG. A chute 3 arranged on the front outer wall 1a
(Low-speed bed) SB for mixing the incinerated material supplied from the above with the layer material FG for drying and pyrolysis, and a pyrolysis zone 4 for burning volatile components above the first bed SB, and transfer air The second bed (high-speed bed) for burning the incineration sent from the first bed SB by the nozzle 5
FB and the air blown from the high-speed combustion air nozzle 6 form a main combustion zone 7 which is blown up above the first bed FB and mixed and burns, and further protrudes from the rear outer wall 1b of the furnace main body 1 to form a main combustion zone. A post-combustion zone 9 in which the blown-up incineration material and the layer material FG are further mixed and burned by the combustion zone 7 and the guide wall 8 which covers the partition wall 2.
And the upper portion of the guide wall 8 and the partition 2 between the table 9a protruding toward the first bed SB and supplying the combustion gas and the layer material FG from the post-combustion zone 9 near the outlet of the supply chute 3. The fuel gas is dropped on the incineration material, and the combustion exhaust gas is discharged through the exhaust gas passage 13 in front of the guide wall 8.
And a circulation passage 10 to be sent out to the upper secondary combustion chamber 11. Reference numeral 12 denotes an ash outlet provided at the bottom of the furnace body 1.

[0004] However, the above configuration has a problem that the heat transfer tube for heat recovery is not provided, and the overall thermal efficiency is low. Other conventional fluidized-bed furnaces equipped with heat transfer tubes and vertically circulating bed material include, for example, installing a heat exchanger room having heat transfer tubes outside the furnace, and introducing bed material in the furnace from a connection port. Circulating a layer material in a furnace through a pumping device (Japanese Patent Laid-Open No. 62-102001), and a heat recovery system having a combustion part having a combustion material inlet and a heat transfer tube by a partition wall in the furnace. And the layer material of the combustion section is sent to the heat recovery section via the upper portion of the partition wall, and the layer material of the heat recovery section is circulated to the combustion chamber through the communication section at the lower portion of the partition wall (Japanese Patent Application Laid-Open JP-A-63-14086).

[0005]

The fluidized-bed furnace of the former type has a problem that unburned components entrained together with the bed material in the heat exchanger chamber are decomposed to generate corrosive gas and corrode the heat transfer tubes. there were. Further, the latter furnace also has a problem that the heat recovery portion has unburned air entrained therein, and the heat transfer tube is heavily corroded.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fluidized-bed furnace having a high thermal efficiency which can solve the above-mentioned problems, reduce the corrosion of the heat transfer tube, and efficiently recover heat.

[0007]

In order to solve the above-mentioned problems, the present invention provides a vertically arranged partition in a furnace main body,
A first bed for drying and preheating the material to be burned supplied from the incinerator chute is provided on one side of the partition, and a second bed for burning the material to be burned is provided on the other side of the bulkhead. In a fluidized bed furnace in which the blown-up layer material and combustion gas are circulated to the first bed side while bypassing the upper end of the partition, a layer material receiving inlet formed in the partition or in the upper part instead of the partition; A heat recovery unit provided with a layer material discharge port for discharging the material to the first bed side and a heat recovery chamber having a plurality of heat transfer tubes for recovering heat from the layer material; And a guide wall which is arranged at a predetermined interval above and which guides the layer material to the layer material receiving port.

The heat recovery chamber having the above-mentioned structure is provided with fluidizing means for fluidizing the layer material at a low speed. further,
In the above configuration, the layer material discharge port is formed at the bottom of the heat recovery chamber.

Further, a layer material discharge means capable of discharging the layer material in the heat recovery chamber is provided at the layer material discharge port having the above configuration.

[0010]

In the above construction, the material to be burned supplied from the incinerator chute is first sent to the first bed and discharged from the layer material discharge port to cover the layer material and the combustion gas discharged from the exhaust gas passage. It is heated by radiant heat to be decomposed and carbonized, and the gas is burned above the first bed. And
The material to be burned sent to the second bed without being burned is burned and blown up together with the layer material. Furthermore, the layer material
After being guided by the guide wall and separated from the combustion gas, introduced into the heat recovery chamber from the layer material receiving port and recovered by the heat transfer tube,
It is discharged onto the first bed from the layer material discharge port.

Therefore, a heat recovery unit is provided on the partition wall where the layer material and the combustion gas bypass the upper end or in place of the partition wall, and the layer material is separated from the combustion gas and the layer material receiving port of the heat recovery unit. The guide wall is provided to guide the heat transfer to the high-temperature heat recovery chamber without the entrainment of the combustion gas, and the heat can be recovered through the heat transfer tube.The heat transfer tube is corroded by the corrosive gas. No wear is caused by the collision of the layer material, and the layer material is not exposed to severe collision of the layer material.

In addition, the bed material in the heat recovery chamber is made to flow at a low speed by the fluidizing means, so that contact with the heat transfer tube is increased and heat can be efficiently recovered. In addition, since the layer materials contact at a low speed, there is almost no wear on the heat transfer tubes.

Further, by forming the layer material discharge port at the bottom of the heat recovery chamber, the layer material can be sequentially sent downward from the upper layer material receiving port, and the flow of the layer material is formed by its own weight and smoothly. The flow of the layer material can be formed, and the container of the heat recovery unit can be made vertically long, so that the volume of the combustion space can be sufficiently secured.

Further, by providing the layer material discharge means at the layer material discharge port, the amount of the layer material circulated to the heat recovery chamber can be easily controlled, and the heat recovery amount can be freely controlled. .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a high-speed circulating fluidized-bed refuse incinerator according to the present invention will be described below with reference to FIGS. The same members as those in the related art are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 1, reference numeral 21 denotes a partition wall (partition wall) for partitioning a first bed SB and a second bed FB, and a heat recovery section 22 is provided on the first bed SB side of the partition wall 21. . The heat recovery part 22 is composed of the partition 21 and the intermediate partition 2.
3, a layer material receiving port 25 having an open upper portion of the heat recovery chamber 24, and a layer material discharge port 26 formed at the bottom of the heat recovery chamber 24. I have. In the heat recovery chamber 24, a plurality of heat transfer tubes 27 are arranged at regular intervals, and for the purpose of effectively recovering heat,
A plurality of low-speed dispersion pipes (fluidization fluid) for fluidizing the bed material FG in the heat recovery chamber 24 at low speed by injecting dispersion air at a speed of 0.2 to 0.5 m / sec from below the heat transfer pipe 27. Means) 28 are provided. Further, the layer material discharge port 26 is formed in a U-shaped passage shape when viewed from the side, the outlet is opened at a lower portion of the intermediate partition wall 23, and the layer material discharge nozzle (layer material discharge means) having an outlet at the bottom thereof in the discharge direction. 29 are provided.
The layer material discharge nozzle 29 is connected to an air header 30 piped in a refractory material below the heat recovery chamber 24, and blows air from the layer material discharge nozzle 29 into the layer material discharge port 26 to recover heat. By discharging the layer material in the chamber 24, the amount of circulation of the layer material FG can be freely controlled.

Reference numeral 31 denotes a guide wall disposed at a predetermined interval above the second bed FB and the heat recovery unit 22, and a horizontal portion 31a extending horizontally from the rear outer wall 1b of the second bed FB. Thereby, a circulation passage 32 for the layer material and the combustion gas CG is formed between the second bed FB and the heat recovery unit 22. Further, a combustion gas passage 33 for guiding the combustion gas CG to the first bed SB side between the hanging portion 31 b bent downward from the tip end of the guide wall 31 and the upper end of the intermediate partition wall 23.
Are formed.

Next, the operation of the above configuration will be described. (A) The incineration material supplied from the chute 3 into the furnace main body 1 falls so as to cover the layer material FG overflowing from the heat recovery part 32 from above in the vicinity of the outlet, and relatively light paper or plastic sheet or the like. Is prevented from scattering.
The material to be incinerated is heated.

(B) The incinerated material quickly drawn into the first bed SB is heated by the radiant heat of the high-temperature combustion gas CG discharged from the combustion gas passage 33 and discharged from the layer material discharge port 26. The layer material FG that has been applied is covered and heated from above, and heat drying and thermal decomposition of the incinerated material are promoted. Then, the volatile components generated from the incineration material are raised to the pyrolysis zone 4, and the combustion exhaust gas discharged from the combustion gas passage 33 is mixed and sufficiently burned, and then further burned.
It is introduced into the next combustion chamber 11 and is completely burned. Further, the heat of combustion generated in the thermal decomposition zone 4 is sufficiently transmitted to the first bed SB, and does not lower the temperature of the material to be burned.
On the other hand, solid matter and undecomposed matter not burned in the first bed SB are sent to the second bed FB by the combustion air supplied from the transfer air nozzle 6.

(C) In the second bed FB, the solids (chars) of the refuse are mainly burned by the air blown from the high-speed combustion air nozzle 6 to form the main combustion zone 7,
Further, the upward flow causes the layer material FG together with the combustion gas CG.
Is blown up.

(D) The layer material FG that has reached the circulation passage 32 is
The heat recovery unit 22 is guided by the hanging portion 31B of the guide wall 31 and
And is sent to the heat recovery chamber 24.
At this time, the layer material FG is completely separated from the combustion gas CG. Then, the layer material FG and the combustion gas CG overflowing from the layer material receiving port 25 are discharged from the combustion gas passage 33 to the pyrolysis zone 4 side.

(E) In the heat recovery section 22, the high-temperature layer material FG is flowed by the low-speed dispersion air ejected from the low-speed dispersion pipe 28 and is brought into contact with the heat transfer pipe 27 at a low speed.
The heat is conducted to the internal heat medium without abrasion and the heat is recovered. Then, the layer material FG after the heat recovery descends and reaches the layer material discharge port 26, and is discharged above the first bed SB by the air injected from the layer material discharge nozzle 29.

According to the above embodiment, (1) after being heated and pyrolyzed in the first bed SB, only combustion is performed in the second bed FB, and further, the second bed FB
The layer material FG blown up from B is introduced into the heat recovery chamber 24 from the layer material receiving port 25 while being completely separated from the combustion gas CG.
Corrosive gas generated by decomposition of unburned components contained in G can be almost eliminated, and corrosion of the heat transfer tube 27 provided in the heat recovery chamber 24 can be prevented. (2) Since the layer material FG in the heat recovery chamber 24 is fluidized by the low-speed air jetted from the low-speed dispersion pipe 28, heat can be efficiently recovered, and the heat transfer tube 27 is also worn due to contact with the layer material FG. Can be extremely small. (3) Layer material discharge nozzle 29 arranged at layer material discharge port 26
By controlling the amount of air from the heat recovery chamber 24, the amount of circulation of the layer material FG into the heat recovery chamber 24 can be freely controlled, and the amount of heat recovered by the heat transfer tube 27 can be arbitrarily controlled.

In the above embodiment, the low-speed dispersion pipe 28 is provided in the heat recovery chamber 24. However, if sufficient heat recovery is possible depending on the state of the incineration object and the layer material, the low-speed dispersion pipe 28 is used. 28
There is no need to provide

Further, in the above embodiment, the heat recovery section 22 is provided on the partition 21, but the heat recovery section itself can also serve as the partition. Furthermore, in the above-described embodiment, the incinerator is an incinerator in which the incinerated material is municipal waste. However, a coal-fired boiler in which highly corrosive gas is easily generated using pulverized coal as the incinerated material may be used.

[0026]

As described above, according to the configuration of the present invention, the partition wall where the stratum and the combustion gas bypass the upper end portion are provided.
Alternatively, instead of the partition walls, a heat recovery section is provided, and a guide wall is provided to separate the layer material from the combustion gas and guide the layer material to the layer material receiving port of the heat recovery section. It can be received in the recovery chamber and heat can be recovered through the heat transfer tubes.The heat transfer tubes are not corroded by the influence of corrosive gas, and are not exposed to severe collision of the layer material. Wear due to material collision can be avoided.

Further, by flowing the layer material in the heat recovery chamber at a low speed by the fluidizing means, the contact with the heat transfer tube can be increased and the heat can be recovered efficiently. In addition, since the layer materials contact at a low speed, there is almost no wear on the heat transfer tubes.

Further, by forming the layer material discharge port at the bottom of the heat recovery chamber, the layer material can be sequentially sent downward from the upper layer material receiving port, so that the flow of the layer material is formed by its own weight and smooth. The flow of the layer material can be formed, and the container of the heat recovery unit can be made vertically long, so that the volume of the combustion space can be sufficiently secured.

Further, by providing the layer material discharge means at the layer material discharge port, the amount of circulation of the layer material to the heat recovery chamber can be easily controlled, and the heat recovery amount can be freely controlled. .

[Brief description of the drawings]

FIG. 1 is a partial side sectional view showing one embodiment of a high-speed circulation type fluidized-bed refuse incinerator according to the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is an overall side sectional view showing a conventional high-speed circulation type fluidized bed incinerator.

[Explanation of symbols]

 SB 1st bed FB 2nd bed FG Layer material CG Combustion gas 1 Furnace body 3 Supply chute 4 Pyrolysis zone 5 Transfer air nozzle 6 High speed combustion air nozzle 7 Main combustion zone 11 Secondary combustion chamber 13 Exhaust gas passage 21 Partition wall 22 Heat Recovery section 23 Intermediate partition wall 24 Heat recovery chamber 25 Layer material receiving port 26 Layer material discharge port 27 Heat transfer tube 28 Low speed dispersion pipe 29 Layer material discharge nozzle 31 Guide wall 31a Horizontal part 31b Hanging part 32 Circulation passage 33 Combustion gas passage

Continued on the front page (56) References JP-A-64-46511 (JP, A) JP-A-58-32237 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F23G 5 / 30 F23C 11/02 301-313

Claims (4)

(57) [Claims] 1. A vertical partition is arranged in a furnace main body, and a first bed for drying and preheating a burned material supplied from an incinerator chute is provided on one side of the partition, and the other side of the partition is provided. A second bed for burning the object to be burned in the portion,
In a fluidized bed furnace in which the bed material and the combustion gas blown up from the bed are circulated to the first bed side while bypassing the upper end of the partition wall, the bed material, or a bed material inlet formed in the upper part instead of the partition wall, A heat recovery unit having a layer material discharge port for discharging the layer material to the first bed side and a heat recovery chamber having a plurality of heat transfer tubes for recovering heat from the layer material; A fluidized-bed furnace provided with a guide wall arranged at a predetermined interval above a recovery unit and guiding a layer material to the layer material receiving port. 2. The fluidized-bed furnace according to claim 1, wherein a fluidizing means for fluidizing the bed material at a low speed is provided in the heat recovery chamber. 3. The fluidized-bed furnace according to claim 1, wherein the bed material discharge port is formed at the bottom of the heat recovery chamber. 4. A fluidized bed furnace according to claim 3, wherein a bed material discharge means capable of discharging the bed material in the heat recovery chamber is provided at the bed material discharge port.