JP3231378B2 - Water injection cooling system for incinerator exhaust gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an electric dust collector, which is attached to a refuse incinerator or a waste incinerator for incinerating municipal waste or industrial waste, and reduces the temperature of exhaust gas discharged from the incinerator. The present invention relates to an apparatus for reducing the temperature of water discharged from an incinerator exhaust gas so as not to adversely affect a bag filter or the like.

[0002]

2. Description of the Related Art Generally, in small and medium incinerators, the temperature of exhaust gas at the outlet of the incinerator is about 75 to prevent odor.
Wastes are incinerated at a high temperature so that the temperature becomes 0 ° C or higher. The high-temperature exhaust gas is removed by an electric precipitator provided in an exhaust gas discharge path of the incinerator, so that the temperature is reduced to a temperature (about 350 ° C. or less) that does not adversely affect the electric precipitator, and then supplied to the electric precipitator. ing. In particular, in recent years, the temperature of exhaust gas has been set to 250 ° C. or lower in order to prevent dioxin generation in an electric dust collector. In recent years, bag filters have been increasingly used in place of electric dust collectors in order to increase the efficiency of removing dioxins present in exhaust gas. In the case of this bag filter, the temperature of the exhaust gas entering the bag filter is required to be about 200 ° C. or less due to the problem of improving the service temperature of the bag and the collection efficiency.

[0003] In order to reduce the temperature of the high-temperature exhaust gas discharged from the incinerator, a water injection cooling device including a water injection cooling tower or the like has conventionally been used. FIG. 2 is a schematic diagram of an exhaust gas treatment system using the water injection temperature reduction device, 31 is a refuse incinerator, 32 is a refuse hopper, 33 is a stoker for refuse incineration, 34 is a primary combustion chamber, and 35 is a secondary combustion chamber. Chamber, 36 is a secondary combustion air nozzle, 37 is a water injection cooling tower, 38 is a water injection nozzle, 39 is an ash discharge door, 40 is an air preheater, 41 is an electric precipitator, 42 is an induced draft fan, 43 is It is a chimney. Exhaust gas G discharged from the incinerator 31 is supplied to the water injection cooling tower 37.
The temperature is reduced to about 300 ° C. by the water injection from the water injection nozzle 38 in the water injection cooling tower 37. The water injection nozzle 38 is controlled so as to automatically adjust the injection water amount based on the exhaust gas temperature at the outlet of the air preheater 40. The exhaust gas whose temperature has been reduced is guided to an electric precipitator 41 via an air preheater 40, where dust is removed therefrom, and then discharged from a chimney 43 to the atmosphere via an induction ventilator 42.

[0004]

However, in the water jet cooling tower 37, it is necessary to completely evaporate the jet water in order to avoid corrosion and failure of the electric precipitator 41 and the like and not to discharge highly acidic and dirty waste water. , And water is sprayed at a particle size of about 150 μm. However, the injection water is very small but does not completely atomize,
The water drops fall and accumulate at the bottom of the cooling tower 37. Further, when water droplets collide with the inner wall surface of the water jet cooling tower 37, they flow along the inner wall surface and accumulate at the bottom. In this manner, the water collected at the bottom of the water jet cooling / cooling tower 37 is drained from a drain port (not shown) formed at the bottom. Since the water is a strong acidic water having a pH of 1, the neutralization treatment is performed. There is a problem that requires. Also, if strongly acidic water accumulates at the bottom, it may ooze out from the bottom, causing a problem of corroding bricks, foundation concrete, or exterior plates such as steel plates at the bottom of the water jet cooling tower 37. Further, the dust in the exhaust gas is separated in the water injection cooling tower 37 and accumulates at the bottom to become muddy. The muddy ash accumulated at the bottom of the water jet cooling tower 37 is scraped by human power by opening the ash discharge door 39 after the work is completed in an incinerator operated for 8 hours a day, but it is strongly acidic. is there. In addition, in an incinerator that operates continuously for one week, a large amount of ash accumulates at the bottom, and it is difficult to take out the ash. In addition, there is a method of using a conveyor for taking out the ash, but the ash has a strong acidity, so that the conveyor may be corroded, and in fact, it is not practically used. On the other hand, in recent years, in an exhaust gas treatment system, since a bag filter is used in a dust collecting device due to a problem of dioxin, it is necessary to lower the temperature of the exhaust gas to about 200 ° C. to 150 ° C. For this reason, an example of installing another water injection cooling tower 37 behind the air preheater 40 (portion A in FIG. 2) is increasing. In this case, the problem of water leakage and the problem of ash are promoted.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and an apparatus for reducing the temperature of water discharged from an incinerator exhaust gas, which can prevent the leakage of strong acid water and can omit the operation of discharging ash. To offer.

[0006]

According to a first aspect of the present invention, there is provided an apparatus for reducing the temperature of water discharged from an incinerator by injecting exhaust gas from an incinerator. And a water injection cooling tower provided with a water injection nozzle for reducing the temperature of the exhaust gas flowing from the exhaust gas inlet, and water and wet water that are provided at the bottom of the water injection cooling tower and fall to the bottom. Fluidized bed apparatus having a fluidized bed for drying dust and soot, a hot gas supply apparatus for supplying hot gas for drying to the fluidized bed of the fluidized bed apparatus, and a water jet cooling tower, which are juxtaposed and discharged from an incinerator. An air preheater that reduces the temperature of a portion of the exhaust gas that has been exhausted, removes the exhaust gas that has passed through the air preheater, recirculates a portion of the exhaust gas to the inlet side of the air preheater, and sprays the remaining exhaust gas with water. The basic configuration of the invention is that it is configured to supply to the cooling tower It is intended to. Further, in the water jet de-cooling device for incinerator exhaust gas according to claim 2, the hot gas supply device is discharged from the water jet de-cooling tower in the water injection de-cooling device of claim 1, and dust is removed. This is a hot gas supply device configured to supply one or both of a part of the exhaust gas and a part of the exhaust gas that has been removed from the air preheater to the fluidized bed.

[0007]

The high-temperature exhaust gas discharged from the incinerator enters the water injection cooling tower from the exhaust gas inlet, is cooled by water injection from the water injection nozzle, and is discharged from the exhaust gas outlet. or,
Part of the high-temperature exhaust gas discharged from the incinerator is guided to an air preheater, where the temperature is reduced. After the exhaust gas cooled down by passing through the air preheater is dedusted, a part of the exhaust gas is recirculated to the inlet side of the air preheater to lower the temperature of the hot exhaust gas supplied to the air preheater and to reduce the temperature of the remaining exhaust gas. Is supplied to the water jet cooling tower. The fluidized bed of the fluidized bed device provided at the bottom of the water jet cooling tower has a portion of the exhaust gas discharged from the water jet cooling tower and removed, and a portion of the exhaust gas removed from the air preheater and removed. Some of them are mixed or supplied alone.
As a result, the fluidized bed in the water jet cooling tower is always in a fluidized state, the water that has fallen from the top during the water injection is evaporated by the fluidizing action of the fluidized bed, and the wet dust is caused to flow by the fluidized bed. It is dried by the action and scatters to the upper part, and is discharged from the exhaust gas outlet. This water injection cooling device evaporates the water falling to the lower part of the water injection cooling tower by the fluidizing action of the fluidized bed,
Further, since the wet dust is dried by the fluidizing action of the fluidized bed and scattered, there is no possibility that strongly acidic water or mud-like ash accumulates at the bottom of the water jet cooling tower. As a result, it is possible to prevent water leakage and to omit the operation of discharging ash. In addition, since the exhaust gas whose temperature has been reduced by the air preheater is supplied to the water injection cooling tower, the amount of water injected in the water injection cooling tower is small, and the evaporation of falling water and the removal of wet dust Drying can be performed reliably and well. Of course, since a part of the low-temperature exhaust gas passing through the air preheater is recirculated to the inlet side of the air preheater, the air preheater is not adversely affected. Furthermore, a part of the exhaust gas discharged from the water jet cooling tower and removed and a part of the exhaust gas removed from the air preheater are mixed or supplied alone to the fluidized bed of the fluidized bed apparatus. Therefore, the temperature of the exhaust gas supplied to the fluidized bed can be arbitrarily changed. As a result, exhaust gas having a temperature corresponding to the drying state of the fluidized bed can be supplied to the fluidized bed, and the evaporation of falling water and the drying of wet dust can be performed more reliably and efficiently.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram of an exhaust gas treatment system using a water injection cooling device according to an embodiment of the present invention, wherein 1 is a water injection cooling device, 2 is an electric dust collector, 3 is an induction ventilator, and 4 is a chimney. is there.

The water jet cooling device 1 comprises a water jet cooling tower 5 provided in an exhaust gas discharge path of an incinerator, a fluidized bed device 6 provided at the bottom of the water jet cooling tower 5, Injection cooling tower 5
Preheater 7 connected to the fluidized bed 1 of the fluidized bed apparatus 6
The hot gas supply device 8 supplies a hot gas (exhaust gas) for drying to the hot gas supply device 6.

Specifically, the water jet cooling tower 5 has a cylindrical shape, and is formed by lining a refractory material on the inner peripheral surface of a cylindrical metal casing, and has an exhaust gas inlet 9 and an exhaust gas outlet on the peripheral wall. And a plurality of water injection nozzles 1 for reducing the temperature of the exhaust gas G flowing from the exhaust gas inlet 9.
1 is provided. The exhaust gas inlet 9 is connected to an exhaust gas outlet of the incinerator via an exhaust gas supply conduit 12, and the exhaust gas outlet 10 is connected to the electric precipitator 2 via an exhaust gas discharge conduit 13.

The fluidized bed device 6 is provided at the bottom of the water jet cooling tower 5, and is for evaporating and drying water and wet dust falling to the bottom at the time of water injection. That is, the fluidized bed apparatus 6 is provided with a fluidized bed 14 for drying provided at the bottom of the water jet cooling and cooling tower 5 and a wind box provided below the fluidized bed 14 for drying and into which hot gas (exhaust gas) is introduced. 15 and a fluidized bed 16 made of silica sand formed on the fluidized bed 14 for drying.
And a fluidized bed nozzle 17 for supplying the hot gas in the wind box 15 to the fluidized bed 16 to flow the silica sand.

The air preheater 7 is arranged in parallel with the water jet cooling tower 5, the inlet side of which is connected to the exhaust gas supply pipe 12 or the exhaust gas outlet of the incinerator via the inlet side pipe 18, and the outlet side is the outlet side pipe. 19, the exhaust gas G (about 750) discharged from the incinerator connected to the water jet cooling tower 5 respectively.
C.) and can be supplied to the water jet cooling tower 5. Further, the inlet side and the outlet side conduit 19 of the air preheater 7 are connected via a circulation conduit 20,
A part of the exhaust gas G exiting the air preheater 7 is recirculated to the inlet of the air preheater 7, and the exhaust gas temperature at the inlet is set to 500 ° C. to 600 ° C.
It is made to lower to about ° C. A cyclone 21 is provided in the outlet conduit 19 to remove dust in the exhaust gas passing through the air preheater 7, and a cyclone 22 is provided in the outlet conduit 19.
, An exhaust ventilator for an air preheater, which sucks the exhaust gas G from the air preheater 7 and supplies the exhaust gas G to the inlet side of the water injection dewarming tower 5 and the air preheater 7;
9 is a damper that is interposed in the circulation pipe 9 and the circulation pipe 20 and that controls the amount of the exhaust gas G supplied to the inlet side of the water injection cooling tower 5 and the air preheater 7.

The hot gas supply device 8 includes an exhaust gas supply conduit 25 connected to the wind box 15, a first conduit 26 connecting the exhaust gas supply conduit 25 and the outlet side of the induction ventilator 3, and an exhaust gas supply conduit 25. A second conduit 27 connecting the exhaust conduit 19 with the outlet side, a fluidized-bed blower 28 disposed in the exhaust gas supply conduit 25, and dampers 29, 30 disposed in the first conduit 26 and the second conduit 27. And a part of the exhaust gas G discharged from the water jet cooling tower 5 and removed by the electric precipitator 2 and a part of the exhaust gas G removed from the air preheater 7 and removed by the cyclone 21 are mixed or used alone. To supply the fluidized bed 16 to the fluidized bed 16 of the fluidized bed apparatus 6. The hot gas supply device 8 controls each of the dampers 29 and 30 to make the first
By adjusting the amounts of the exhaust gas G in the conduit 26 and the second conduit 27, respectively, the temperature of the exhaust gas G supplied to the wind box 15 can be arbitrarily adjusted.

Next, the operation of the water injection temperature reducing device 1 will be described. Exhaust gas G discharged from the incinerator (about 750
° C or higher) enters the water injection cooling tower 5 through the exhaust gas inlet 9 and is injected into the water injection nozzle 11 by water injection from the water injection nozzle 11.
After the temperature is reduced to about 50 ° C., the exhaust gas is discharged from the exhaust gas outlet 10, dust is removed by the electric dust collector 2, and then discharged to the atmosphere from the chimney 4 through the induction draft fan 3. Then, a part of the exhaust gas G (about 750 ° C. or higher) discharged from the incinerator is guided to the air preheater 7 and preheats the air before the cyclone 21.
, And is introduced into the water jet cooling tower 5 at a temperature of about 350 ° C. through the air preheater induction ventilator 22. or,
A part of the exhaust gas G that has exited the air preheater induction ventilator 22 is recirculated to the inlet side of the air preheater 7, and the temperature of the high-temperature (approximately 750 ° C. or higher) exhaust gas G supplied to the air preheater 7 is reduced by 50%.
Lower to about 0 ° C to 600 ° C. On the other hand, the fluidized bed 16 provided at the bottom of the water injection cooling tower 5 has a part of the exhaust gas G discharged from the water injection cooling tower 5 and removed, and the exhaust gas removed from the air preheater 7 and removed. A part of G is supplied in a mixed state.
That is, a part of the exhaust gas G (about 150 ° C.) that has exited the induction ventilator 3 and the exhaust gas G (about 3 ° C.) that exited the induction ventilator 22 for the air preheater.
(00 ° C.) is sucked by the fluidized bed blower 28, passes through the wind box 15,
Is supplied inside to make the silica sand flow. As a result, the fluidized bed 16 in the water jet cooling and cooling tower 5 is always in a fluidized state, the water that has fallen from the top during the water jet is evaporated by the flow action of the silica sand, and the wet dust is the flow of the silica sand. It is dried by the action and scatters to the upper part, discharged from the exhaust gas outlet 10 and collected by the electric precipitator 2. The water injection cooling device 1 evaporates water falling to the lower portion of the water injection cooling tower 5 by the fluidizing action of the fluidized bed 16 and also dries and scatters wet dust by the fluidizing action of the fluidized bed 16. Therefore, it does not mean that strongly acidic water accumulates at the bottom of the water jet cooling / cooling tower 5 to cause water leakage, and that it is not necessary to discharge ash. Further, since a part of the exhaust gas G whose temperature is reduced by the air preheater 7 is supplied to the water injection cooling tower 5, the amount of water injected in the water injection cooling tower 5 can be reduced,
Evaporation of falling water and drying of wet dust can be performed reliably and well. Further, since part of the low-temperature exhaust gas G discharged from the air preheater 7 is recirculated to the inlet side of the air preheater 7, the air preheater 7 is not adversely affected. Of course, by adjusting the ratio of the exhaust gas G exiting the induction ventilator 3 and the exhaust gas G exiting the air preheater induction ventilator 22, the fluidized bed 1
Since the temperature of the exhaust gas G supplied to the fluidized bed 6 can be arbitrarily changed, the exhaust gas G having a temperature corresponding to the dry state of the fluidized bed 16 can be supplied to the fluidized bed 16, and the falling water is evaporated and wet. Dust can be more reliably and efficiently dried.

In the above embodiment, the exhaust gas G exiting the induction ventilator 3 in the wind box 15 and the induction ventilator 22 for the air preheater are used.
The exhaust gas G that has flowed out is mixed and supplied, but in another embodiment, only one of the exhaust gas G may be supplied.

In the above embodiment, the cross section of the water jet cooling tower 5 is circular, but in other embodiments, the cross section may be square.

[0017]

As described above, the water jet cooling apparatus of the present invention is provided with a fluidized bed apparatus having a fluidized bed at the bottom of a water jet cooling tower for cooling exhaust gas. Since the hot gas supply device that supplies gas is provided, the water falling to the lower part of the water jet cooling tower is evaporated by the fluidizing action of the fluidized bed, and the wet dust is evaporated by the fluidizing action of the fluidized bed. It can be dried and scattered. as a result,
It is possible to prevent the leakage of water and the ash discharge operation without strongly acidic water or muddy ash accumulating at the bottom of the water jet cooling tower. According to the devices of claims 2 and 3, in addition to the above effects, the following effects can be further obtained. That is, in the device of claim 2, an air preheater for reducing the temperature of a part of the exhaust gas discharged from the incinerator is provided in the water injection dewarming tower, and a part of the reduced temperature exhaust gas is provided. Since the water injection cooling tower is configured to be supplied to the water injection cooling tower, the amount of water injected in the water injection cooling tower is small, and the evaporation of falling water and the drying of wet dust can be performed reliably and well. Further, since a part of the low-temperature exhaust gas discharged from the air preheater is recirculated to the inlet side of the air preheater, the air preheater is not adversely affected. In the apparatus according to claim 3, a part of the exhaust gas discharged from the water jet cooling tower and removed and a part of the exhaust gas removed from the air preheater are mixed or used alone or in a fluidized bed apparatus. Because it was configured to supply to the fluidized bed of
The temperature of the exhaust gas supplied to the fluidized bed can be changed arbitrarily. As a result, exhaust gas having a temperature corresponding to the drying state of the fluidized bed can be supplied to the fluidized bed, and the evaporation of falling water and the drying of wet dust can be performed more reliably and efficiently.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an exhaust gas treatment system using a water injection cooling device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an exhaust gas treatment system using a conventional water injection cooling device.

[Explanation of symbols]

1 is a water injection cooling device, 5 is a water injection cooling tower, 6 is a fluidized bed device, 7 is an air preheater, 8 is a hot gas supply device, 9 is an exhaust gas inlet, 10 is an exhaust gas outlet, and 11 is a water injection nozzle. , 16 is a fluidized bed.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F23J 15/00-15/08 B01D 51/00 B03C 3/014 B01D 50/00 B01D 51/04 B01D 51 / Ten

Claims (2)

(57) [Claims] 1. A water interposed in a discharge path of exhaust gas discharged from an incinerator , having an exhaust gas inlet and an exhaust gas outlet, and having a water injection nozzle for reducing the temperature of the exhaust gas flowing from the exhaust gas inlet. An injection cooling tower, a fluidized bed apparatus provided at the bottom of the water injection cooling tower, and having a fluidized bed for drying water and wet dust falling to the bottom, and a fluidized bed of the fluidized bed apparatus for drying. A hot gas supply device that supplies hot gas and reduced water injection
A part of the exhaust gas discharged from the incinerator
An air preheater for decreasing the temperature, passing through the air preheater.
Exhaust gas and remove a part of it to the inlet side of the air preheater.
Circulates and supplies the remaining exhaust gas to the water jet cooling tower.
A water injection cooling device for incinerator exhaust gas, characterized by having a configuration as described above . 2. A method hot gas supply apparatus, flow either one or both of a part of a portion the exhaust gas air preheater is dust out of the exhaust gas was dedusted is discharged from the water injection down cooling tower
2. The apparatus for reducing the temperature of water discharged from incinerator exhaust gas according to claim 1 , wherein the apparatus is a hot gas supply apparatus configured to supply the gas to the bed .