JP7051325B2 - Fly ash manufacturing equipment and manufacturing method - Google Patents

Description

The present invention is a fly ash suitable for a concrete admixture by sufficiently removing unburned carbon remaining in the coal ash when producing a concrete admixture from coal ash discharged from a coal-fired boiler. Regarding the manufacturing apparatus and manufacturing method, in particular, regarding the manufacturing apparatus and manufacturing method of highly homogeneous and stable fly ash.

In paper mills and power plants, high-pressure steam obtained by a coal-fired boiler that burns coal into pulverized coal is used to generate electricity to obtain electric power in the factory and commercial electric power. In this coal-fired boiler, coal ash is produced as so-called burnt residue, but it is necessary to recover it for the smooth operation of the boiler. The recovered coal ash is discarded or recycled as industrial waste, but when it is disposed of, the landfill site is restricted and there are problems of environmental protection. Therefore, it is required to recycle the recovered coal ash as much as possible.

As one of the recycling of coal ash, it is used as an admixture for concrete. In order to use it as an admixture for concrete, it is necessary to remove unburned carbon contained in coal ash to generate fly ash suitable for the admixture for concrete. Due to the difference in the degree of powder, etc., the quality of four categories, high quality type I to low quality type IV, is specified.

As a method for removing unburned carbon, Patent Document 1 describes that the raw material fly ash containing unburned carbon is heated to the self-combustion temperature of the unburned carbon while being stirred and fluidized, and then self-combusted by maintaining the heating temperature. Then, a method for producing the modified fly ash, which is indirectly cooled to recover the modified fly ash, is disclosed.

Further, in Patent Document 2, coal ash is supplied from the upper end portion of a rotary kiln having an inclination to the apparatus for stirring and flowing, and hot gas is supplied from the lower end portion to incinerate unburned matter. A method for removing unburned substances inside is disclosed.

Further, in Patent Document 3, high temperature air and coal ash are introduced into a cyclone, and the unburned carbon in the coal ash is burned by heating the coal ash particles in a suspended state in the high temperature air. Then, after separating the coal ash from which the unburned carbon has been removed and the combustion gas, the coal ash is classified into coarse powder and fine powder by a classifier, and the fine powder is fly ash. A method for treating coal ash to be recovered as an admixture for cement is disclosed.

Japanese Patent No. 4883623 Japanese Patent No. 3629577 Japanese Patent No. 3205770

In the production of fly ash disclosed in each of Patent Document 1, Patent Document 2, and Patent Document 3 described above, homogenization of the produced fly ash has not been sufficiently achieved. For example, it is difficult to produce only fly ash that corresponds to type I according to the JIS standard, and the actual situation is that fly ash that is a mixture of type I and type II is produced.

In particular, in the invention disclosed in Patent Document 3, homogenization is attempted by subjecting the generated fly ash to a classifier for classification, and a device for classification is required, and a large fly is required. There is a risk of becoming an ash manufacturing device.

Therefore, it is an object of the present invention to improve the quality of the produced fly ash and to provide a homogeneous fly ash production apparatus and method.

As a technical means for achieving the above object, the fly ash manufacturing apparatus according to the present invention cools the fly ash discharged by being calcined by a calcining apparatus to which coal ash is supplied to remove unburned carbon. In a fly ash manufacturing apparatus that is cooled by an apparatus to produce fly ash, the combustion air discharged from the firing apparatus for firing coal ash in the firing apparatus is supplied without passing through the cooling apparatus, and the combustion is performed. A separation device that separates the solid content and the gas content contained in the air and a dust collector that supplies the gas content separated by the separation device are provided, and the solid content captured by the dust collection device is collected in the product tank. It is characterized by sending to.

The solid content captured by the dust collector is fly ash from which most of the unburned carbon has been removed, and it is of high quality. Therefore, the product is fly ash, which is the solid content captured by the dust collector. Is. Conventionally, the solid content captured by the dust collector is supplied to the firing device again and reburned.
Further, the fly ash manufacturing apparatus described above includes a heat exchanger that introduces the combustion air discharged from the firing apparatus to the high temperature side, and supplies the combustion air that has passed through the heat exchanger to the separation apparatus. Can be characterized by doing.

Further, it is preferable that the fly ash manufacturing apparatus described above uses a bag filter for the dust collector .

A bug filter is used for the dust collector. By using a bag filter, it is possible to capture fine-grained fly ash, so we are trying to collect better quality products.

Further, in the method for producing fly ash according to the present invention, in the method for producing fly ash in which unburned carbon is removed by burning coal ash with a firing device, the method for producing fly ash is used for burning coal ash in the firing device. The combustion air supplied and discharged from the combustion device is supplied to the separation device without passing through the cooling device, separated into the gas component and the solid component contained in the combustion air, and the gas component separated by the separation device. Is supplied to a dust collector and separated into a gas component and a solid component, and the solid component captured by the dust collector is used as a fly ash product.
Further, in the above-mentioned fly ash manufacturing method, the combustion air discharged from the firing device is introduced into the high temperature side of the heat exchanger, and the combustion air passed through the heat exchanger is supplied to the separation device. Can be characterized.

Further, it is preferable that a bag filter is used in the dust collector in the above-mentioned method for manufacturing fly ash.

According to the fly ash manufacturing apparatus and manufacturing method according to the present invention, the solid content captured by the dust collector is in a state where the coal ash is calcined well and the unburned carbon contained therein is almost completely removed. Because there is, you can get high quality fly ash. Therefore, the best fly ash as an admixture for concrete can be produced.

Further, according to the fly ash manufacturing apparatus or manufacturing method according to the present invention, fly ash made of as fine particles as possible can be captured, and a high-quality admixture for concrete made of high-quality fly ash can be obtained.

It is a figure explaining the fly ash manufacturing apparatus which concerns on this invention, and is the figure which shows the firing apparatus suitable for this manufacturing apparatus. It is a figure explaining until the fly ash generated by firing by the firing apparatus shown in FIG. 1 is made into a product, and describes the process from the cooling apparatus to the product tank, and the process of processing the combustion air discharged from the firing apparatus. This is a step following the firing device shown in FIG. 1, and a part of the firing device is also shown.

Hereinafter, the fly ash manufacturing apparatus and manufacturing method according to the present invention will be specifically described based on the preferred embodiment shown.

As shown in FIG. 1, the coal ash recovered by being used as fuel for a coal-fired boiler is supplied to the raw material tank 1 as a raw material for fly ash production. A raw material hopper 2 is connected to the discharge port of the raw material tank 1 via a supply pipe 1a, and a raw material transfer device including a screw conveyor for feeding to a rotary kiln 3 which is a combustion device while adjusting the supply amount. Supplied to 2a. A combustion assist burner 3a is arranged on the supply port side of the rotary kiln 3, and a first burner 3b, a second burner 3c, and a third burner 3d are arranged in order from the supply side to the discharge port side of the rotary kiln 3 and are supplied. The coal ash moves in the rotary kiln 3 with stirring, and is heated and fired by these burners. There are various types of rotary kiln 3, and any type can be used.

A discharge hopper 3e for collecting fired and generated fly ash is arranged on the discharge port side of the rotary kiln 3, and the fly ash is a fly ash transport device such as a screw conveyor arranged under the discharge hopper 3e. It is offered to 4.

As shown in FIGS. 1 and 2, a cooling device 5 is connected to the discharge port of the fly ash transport device 4 via a duct 4a, and the transported fly ash passes through the duct 4a to be a cooling device. It is supplied to 5. A fly ash supply pipe 6 cooled by the cooling device 5 and a recovery blower 23 are connected to the discharge port side of the cooling device 5, and supply air is supplied to the supply pipe 6 from the recovery blower 23. ing. A first product tank 7 is connected to the end of the supply pipe 6, and the fly ash is conveyed by the supply air of the recovery blower 23 and stored in the first product tank 7.

Further, a branch pipe 6a is connected in the middle of the feed pipe 6, and a temporary tank 8 is connected to the end of the branch pipe 6a. The switching valves 9a and 9b are provided, and the fly ash discharged from the cooling device 5 is supplied to either the first product tank 7 or the temporary tank 8 by switching the opening and closing of the switching valves 9a and 9b. It is possible to switch between.

A switching pipe 8a is connected to the downstream side of the switching valve 9b of the branch pipe 6a, and this switching pipe 8a is connected to the recovery air blower pipe 11a via the switching valve 8b. Further, a switching valve 6b is provided on the temporary tank 8 side of the connection portion with the switching pipe 8a, which is a part of the branch pipe 6a. The recovery blower pipe 11a is connected to the discharge port of the recovery blower 11, and the end is connected to the second product tank 11c. A switching valve 11b is arranged on the downstream side of the connection portion of the recovery blower pipe 11a with the switching pipe 8a.

An exhaust pipe 12 for discharging the combustion air used for burning coal ash in the rotary kiln 3 to the outside is connected to the upper part of the discharge hopper 3e. The end of the discharge pipe 12 is connected to the high temperature side of the auxiliary heat exchanger 21. The combustion air discharged from the auxiliary heat exchanger 21 is introduced into the cyclone separator 13 which is a separation device via the return pipe 12c. An outside air introduction pipe 12a for introducing outside air is connected in the middle of the return pipe 12c.

The solid component separated by the cyclone separator 13 is connected to the return pipe 14 whose end is connected to the raw material hopper 2 via the cyclone recovery pipe 13a, and the return pipe 14 is connected to the discharge port of the outside air introduction blower 14a. It is connected and blown air is introduced. Further, the gas content separated by the cyclone separator 13 contains fly ash, which is supplied to the bag filter 16 which is a dust collector via the exhaust pipe 15. Further, an outside air introduction pipe 15a is connected in the middle of the exhaust pipe 15, and outside air is introduced into the bag filter 16 together with the gas component.

The gas separated by the bag filter 16 becomes clean air and is discharged to the outside through the exhaust pipe 16b. Further, the solid content captured by the bag filter 16 is supplied to the return pipe 14 via the dust collection / recovery pipe 16a.

The cyclone collection pipe 13a and the dust collection collection pipe 16a are connected by a collection pipe 17. The cyclone recovery pipe 13a is provided with a switching valve 13b so that the solid content separated by the cyclone separator 13 can be switched between the case of supplying the solid content to the return pipe 14 and the case of supplying the solid content to the collection pipe 17. Further, the dust collection / recovery pipe 16a is provided with a switching valve 16c so that the solid content captured by the bag filter 16 can be switched between the case of supplying the solid content to the return pipe 14 and the case of supplying the solid content to the collection pipe 17. It is set to. The collection pipe 17 is arranged on the upstream side with respect to any of the switching valves 13b and 16c, and the collection pipe 17 is provided with switching valves 17a and 17b. The recovery air pipe 11a is connected to the intermediate portion of the collection pipe 17 at a position between the switching valves 17a and 17b.

The combustion air introduced to the high temperature side of the sub heat exchanger 21 heats the air introduced from the outside air introduction blower 22 to the low temperature side of the sub heat exchanger 21 via the discharge side pipe 22a.

The air heated by the sub-heat exchanger 21 is introduced into the introduction pipe 21a, and the introduction pipe 21a is introduced to the low temperature side of the main heat exchanger 24. On the other hand, on the high temperature side of the main heat exchanger 24, the discharged high temperature air discharged from the jacket portion 3f provided on the outer periphery of the rotary kiln 3 is introduced, and the air introduced on the low temperature side is heated. The discharged high-temperature air used for heating is discharged to the outside.

The burner combustion high temperature gas from the first burner 3b, the second burner 3c, and the third burner 3d and the outside air introduced from the outside air introduction blower 25 via the cooling air pipe 25a are the jacket portion 3f. It is mixed inside and introduced as discharged high temperature air to the high temperature side of the main heat exchanger 24 through the discharge pipe 25b.

The air introduced to the low temperature side of the main heat exchanger 24 and heated by the discharged high temperature air is sent to the combustion auxiliary burner 3a as the combustion air of the rotary kiln 3 via the combustion air pipe 24a, and the other It is supplied to each of 1 burner 3b, 2nd burner 3c, and 3rd burner 3d. Fuel kerosene is supplied to each of these burners 3a, 3b, 3c, and 3d, and the mixing ratio of the fuel kerosene and combustion air is connected to each of the burners 3a, 3b, 3c, and 3d. It can be adjusted by changing the opening degree of the fuel regulating valve 24d and the air regulating valve 24e provided in each of the fuel supply pipe 24b and the air introduction pipe 24c.

The operation of the fly ash manufacturing apparatus according to the present invention configured as described above will be described below.

The coal ash of the burnt residue that has become the boiler fuel of the coal-fired boiler is stored in the raw material tank 1. It is supplied from this storage tank to the raw material hopper 2, is supplied to the raw material transfer device 2a while being appropriately weighed, and is supplied into the rotary kiln 3. The supplied coal ash is heated to the combustion temperature by the combustion assist burner 3a and the first burner 3b. The coal ash is spirally conveyed by the rotation of the rotary kiln 3 and gradually moved toward the discharge hopper 3e while being agitated by a stirring device (not shown) such as a shelf-shaped lifter provided on the inner wall surface of the rotary kiln 3. During this movement, it is heated by the second burner 3c and the third burner 3d and moves while self-burning. Combustion of this coal ash removes unburned carbon to produce fly ash. When the third burner 3d passes through the facing portion, the heating is released, the combustion of fly ash is calmed down, and the fly ash is fed to the discharge hopper 3e.

Further, in the jacket portion 3f arranged on the outside of the rotary kiln 3, the burner combustion high temperature gas from the first burner 3b, the second burner 3c, and the third burner 3d and the outside air introduced from the outside air introduction blower 25 are mixed. And discharged hot air is generated. This discharged high temperature air is discharged to the discharge pipe 25b and introduced to the high temperature side of the main heat exchanger 24. The outside air is introduced to the low temperature side of the main heat exchanger 24 by the outside air introduction blower 22, and the heated air heated by exchanging heat with the combustion air of the rotary kiln 3 by the auxiliary heat exchanger 21 is guided to the introduction pipe 21a. Then, it is further heated by the main heat exchanger 24 by the high temperature air discharged from the jacket portion 3f of the rotary kiln 3 and discharged to the combustion air pipe 24a as combustion air. The combustion air is supplied to the respective air introduction pipes 24c of the combustion auxiliary burner 3a, the first burner 3b, the second burner 3c, and the third burner 3d through the combustion air pipe 24a. For each of the burners 3a, 3b, 3c, and 3d, the supply amount of the kerosene for fuel and the air for combustion is adjusted by the fuel regulating valve 24d and the air regulating valve 24e to obtain the optimum combustion efficiency. It is done like this.

The fly ash supplied to the discharge hopper 3e is provided to the fly ash transport device 4, and is supplied to the cooling device 5 via the duct 4a. In the cooling device 5, the fly ash is conveyed to the discharge port while being cooled and supplied to the supply pipe 6. Since the discharge side of the recovery blower 23 is connected to the feed pipe 6, the fly ash in the feed pipe 6 is conveyed by the air blown by the recovery blower 23. At this time, the transport destination can be selected from the first product tank 7 and the temporary tank 8 depending on the open / closed state of the switching valves 9a and 9b. For example, at the start of operation of the rotary kiln 3, the operation is not in a steady state and the internal temperature of the rotary kiln 3 does not rise sufficiently, so that the firing is insufficient and the unburned carbon contained in the raw material coal ash is sufficiently removed. A fly ash that has not been produced is generated. In this case, since the quality of the product is low, the switching valve 9a is closed, the switching valve 9b is opened, and the feed pipe 6 and the branch pipe 6a communicate with each other. As a result, fly ash from which unburned carbon has not been sufficiently removed is introduced into the temporary tank 8. On the other hand, when the operation is in a steady state, good firing can be performed, and fly ash from which unburned carbon is sufficiently removed is produced. In this case, the switching valve 9a is opened and the switching valve 9b is closed so that the connection between the feed pipe 6 and the branch pipe 6a is cut off, and the feed pipe 6 is the first product tank 7. Switch to the state of communicating with. As a result, the generated fly ash is not fed to the temporary tank 8, but is fed to the first product tank 7 and stored. Therefore, it is possible to obtain fly ash with stable quality. Even during steady operation, for example, when the first product tank 7 is full, the fly ash in the first product tank 7 should be fed to the temporary tank 8 to discharge the fly ash. It can also be.

Combustion air used for combustion of unburned carbon is discharged from the upper part of the discharge hopper 3e. The discharged combustion air is supplied to the high temperature side of the auxiliary heat exchanger 21 through the exhaust pipe 12, and the outside air introduced by the outside air introduction blower 22 is heated and discharged. The discharged combustion air is supplied to the cyclone separator 13 through the return pipe 12c, and is separated into a solid component and a gas component of fly ash contained in the combustion air. The separated solid component is discharged to the cyclone recovery pipe 13a, and the gas component is discharged to the exhaust pipe 15.

Since the gas component discharged to the exhaust pipe 15 contains fly ash, the bag filter 16 is used to further separate the solid component and the gas component of the fly ash. The separated gas component is discharged to the outside from the exhaust pipe 16b.

The fly ash captured by the bag filter 16 is introduced into the dust collection pipe 16a. The dust collection and recovery pipe 16a is connected to the return pipe 14, and is returned to the raw material hopper 2 through the return pipe 14 by the blown air of the outside air introduction blower 14a. Further, the solid component separated by the cyclone separator 13 reaches the return pipe 14 from the cyclone recovery pipe 13a and is returned to the raw material hopper 2.

By the way, when the rotary kiln 3 is in a steady operating state, the fly ash, which is a solid component captured by the bag filter 16, is of high quality from which unburned carbon is sufficiently removed, and is an admixture for concrete. It is desirable to supply it as a product to the product tank because it is of good quality. Therefore, when the rotary kiln 3 is in steady operation, the switching valve 16c is closed, the switching valve 17b is opened, the dust collection pipe 16a is communicated with the collection pipe 17, and the pipe reaches the return pipe 14. Block the road. Since the collection pipe 17 is connected to the recovery air pipe 11a, high-quality fly ash is supplied to and stored in the second product tank 11c through the recovery air pipe 11a. At this time, the switching valve 8b is closed and the switching valve 11b is opened. On the other hand, when the rotary kiln 3 is not in steady operation, the unburned carbon is not sufficiently removed, so that the switching valve 16c is opened and the switching valve 17b is closed. As a result, the dust collection / recovery pipe 16a is communicated with the return pipe 14 so that the fly ash captured by the bag filter 16 is returned to the raw material hopper 2. When the fly ash is collected in the temporary tank 8, both the cyclone collection pipe 13a of the cyclone separator 13 and the dust collection collection pipe 16a of the bag filter 16 are communicated with the collection air pipe 11a to form the switching valve 8b. The switching valve 6b is opened, the switching valve 11b and the switching valve 9b are closed, and the recovery air flow pipe 11a is communicated with the temporary tank 8 via the switching pipe 8a.

Further, as described above, the solid content captured by the bag filter 16 is of high quality as fly ash and is more homogeneous than the fly ash obtained in the normal manufacturing process via the cooling device 5. Therefore, by storing the fly ash captured by the bag filter 16 separately from the fly ash acquired in the normal manufacturing process, the fly ash has a higher added value than the fly ash acquired in the normal manufacturing process. You can get ash. That is, the fly ash captured by the bag filter 16 is stored in the second product tank 11c so as to be distinguished from the fly ash stored in the first product tank 7.

On the other hand, if it is inconvenient for the fly ash to be fed the recovery air pipe 11a to be stored in the second product tank 11c, the switching valve 11b and the switching valve 9b are closed, and the switching valve 8b and the switching valve 6b are closed. By opening the space, it may be collected in the temporary tank 8. Further, when the second product tank 11c is full, for example, it is wasteful to collect this high quality fly ash in the temporary tank 8. In this case, the fly ash captured by the bag filter 16 can be fed to the first product tank 7. In this case, the switching valve 11b and the switching valve 6b are closed, and the switching valve 8b, the switching valve 9b, and the switching valve 9a are opened, so that the recovery air pipe 11a is connected to the first product tank via the supply pipe 6. It suffices to communicate with 7.

Similarly, in the cyclone separator 13, if the solid unburned carbon separated when the rotary kiln 3 is in steady operation is sufficiently removed, the switching valve 13b is closed and the switching valve 13b is closed. The switching valve 17a is opened to allow the cyclone recovery pipe 13 to communicate with the collection pipe 17. As a result, fly ash, which is a solid component separated by the cyclone separator 13, is supplied from the collection pipe 17 to the second product tank 11c through the recovery air pipe 11a. Further, when the rotary kiln 3 is not in steady operation or is a solid component in which unburned carbon is not sufficiently removed even during steady operation, the switching valve 13b is opened and the switching valve 17a is closed. The cyclone recovery pipe 13a is communicated with the return pipe 14 and returned to the raw material hopper 2. Even in this case, the high-quality fly ash captured by the bag filter 16 can be introduced into the collection pipe 17 and supplied from the recovery air pipe 11a to the second product tank 11c.

The combustion air introduced from the exhaust hopper 3e into the exhaust pipe 12 is introduced to the high temperature side of the auxiliary heat exchanger 21. Since the outside air is supplied to the low temperature side by the outside air introduction blower 22 to the auxiliary heat exchanger 21, the outside air is heated and supplied to the low temperature side of the main heat exchanger 24 through the introduction pipe 21a. To. Therefore, the outside air heated by the auxiliary heat exchanger 21 is introduced to the low temperature side of the main heat exchanger 24, and the temperature is raised. As a result, the temperature of the combustion air discharged from the main heat exchanger 24 rises and is supplied to the burners 3a, 3b, 3c, and 3d. Therefore, the heat recovery of the fly ash manufacturing apparatus becomes good, and the energy saving efficiency can be improved.

According to the fly ash manufacturing apparatus or manufacturing method according to the present invention, a solid captured by a dust collector that purifies the exhaust air in order to exhaust the combustion air used for burning coal ash in the firing apparatus to the outside air. Since most of the unburned carbon is removed from the fly ash, which is a minute, and it is of high quality, storing it individually contributes to collecting high quality fly ash.

1 Raw material tank
1a Supply pipe 2 Raw material hopper
2a Raw material transfer device 3 Rotary kiln (firing device)
3a Fuel burner
3b 1st burner
3c 2nd burner
3d 3rd burner
3e discharge hopper
3f Jacket part 4 Fly ash transfer device
4a Duct 5 Cooling device 6 Feed pipe
6a branch pipe
6b Switching valve 7 1st product tank 8 Temporary tank
8a switching tube
8b switching valve
9a switching valve
9b switching valve
11 Recovery blower
11a Recovery blower pipe
11b switching valve
11c 2nd product tank
12 Exhaust pipe
12a Outside air introduction pipe
12c return tube
13 Cyclone separator (separator)
13a Cyclone recovery tube
13b switching valve
14 Return pipe
14a Outside air introduction blower
15 Exhaust pipe
15a Outside air introduction pipe
16 Bug filter (dust collector)
16a Dust collection pipe
16b Exhaust pipe
16c switching valve
17 Collection tube
17a switching valve
17b switching valve
21 Secondary heat exchanger
21a Introductory pipe
22 Outside air introduction blower
22a Discharge side piping
23 Recovery blower
24 Main heat exchanger
24a Combustion air pipe
24b fuel supply pipe
24c air introduction pipe
24d fuel control valve
24e Air regulating valve
25 Outside air introduction blower
25a cooling air pipe
25b discharge pipe

Claims (6)

In a fly ash manufacturing device that manufactures fly ash by cooling the fly ash discharged by firing in a firing device to which coal ash is supplied and removing unburned carbon with a cooling device.
A separation device that separates the solid component and the gas component contained in the combustion air by supplying the combustion air discharged from the firing device for firing the coal ash in the firing device without passing through the cooling device .
A dust collector for supplying the gas separated by the separation device is provided.
A fly ash manufacturing device characterized in that a solid component captured by the dust collector is fed to a product tank. The fly ash manufacturing apparatus according to claim 1.
It is equipped with a heat exchanger that introduces the combustion air discharged from the firing device to the high temperature side.
A fly ash manufacturing apparatus characterized in that combustion air that has passed through the heat exchanger is supplied to the separation device. The fly ash manufacturing apparatus according to claim 1 or 2.
A fly ash manufacturing device characterized in that a bag filter is used in the dust collector. In the method of producing fly ash, which produces fly ash by calcining coal ash with a calcining device to remove unburned carbon.
The combustion air discharged from the combustion device for burning coal ash in the firing device is supplied to the separation device without passing through the cooling device, and is separated into gas and solid components contained in the combustion air .
The gas content separated by the separation device is supplied to the dust collector to separate the gas component and the solid component.
A method for producing fly ash, which comprises using the solid content captured by the dust collector as a fly ash product. The method for producing fly ash according to claim 4.
Combustion air discharged from the firing device is introduced into the high temperature side of the heat exchanger to be introduced.
A method for producing fly ash, which comprises supplying combustion air that has passed through the heat exchanger to the separation device. The method for producing fly ash according to claim 4 or 5.
A method for manufacturing fly ash, which comprises using a bag filter in the dust collector.

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