JPH10246419A - Processing method of bed ashes of fluidized bed boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To end dumping of bed ashes and to enable effective utilization thereof by crushing the bed ashes discharged from a furnace bottom part of a fluidized bed boiler and by mixing them with fly ashes collected from a flue. SOLUTION: At the time when an ash level of a bed ash silo is a specified value or above, a rotary valve 3b is started and surplus bed ashes B in the silo are sent to a classifying device 4. Herein the ashes having already become fine grains are sent to a fly ash silo 2 through pipings 7e and 7f by air sent from a blower 6 through a piping 7b. The ashes being large grains are sent to a crusher 5 through a piping 7a and they are crushed herein into fine grains, discharged from a piping 7d and sent to the fly ash silo 2 through pipings 7c and 7f by the air sent from the blower 6. The bed ashes being the fine grains originally and those made the fine grains by the crusher are partly recycled to a boiler, while surplus fly ashes are utilized effectively as a cement material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bed ash treatment method for a fluidized-bed boiler.

[0002]

2. Description of the Related Art FIG. 2 is a system diagram of a conventional ash treatment apparatus for a fluidized-bed boiler. There are two types of ash in a fluidized-bed boiler, the first being bed ash discharged from the furnace bottom and the second being fly ash collected in a flue. In the figure, reference numeral 1 denotes a bed ash silo, into which bed ash is introduced. Reference numerals 3a and 3b denote rotary valves provided at the lower part of the bed ash silo, 6 denotes a blower for conveying ash by air, 10
Is a transport vehicle. Reference numeral 2 denotes a fly ash silo, into which fly ash is supplied from above. 8a, 8b
Is a rotary feeder provided below the fly ash silo.

In this apparatus, a bed ash silo 1
A part of the bed ash stored in the boiler is discharged by a rotary valve 3a in an amount required for controlling a combustor differential pressure of a fluidized bed boiler, conveyed to a boiler by air sent from a blower 6, and recycled. Since the amount of bed ash recycled is smaller than the amount of the bed ash, the surplus bed ash B is discharged from the rotary valve 3b, received by the transport vehicle 10, and dumped at the dumping site 11 such as a landfill.

A part C of the fly ash stored in the fly ash silo 2 is supplied to the rotary feeder 8 in the same manner as described above.
The air discharged from the blower 6 is conveyed to the boiler by the air sent from the blower 6 and recycled. Excess fly ash D is discharged from the rotary feeder 8b and used as a cement material.

The bed ash particle size of a fluidized-bed boiler is about 10 to 20 times as large as the fly ash particle size (10 to 20 μm) and cannot be reused as a raw material for cement or the like. .

[0006]

The conventional ash treatment method causes air pollution because dust soars when bed ash is discarded. Humidification is performed as a general dust prevention means. However, since lime powder is present in bed ash and hardens when water is added, there is a disadvantage that humidification treatment cannot be performed. For this reason, it has been necessary to treat excess bed ash by a method other than dumping.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art, and has as its object to provide a means for preventing discard of bed ash and effectively using the bed ash.

[0008]

According to the present invention, there is provided a fluidized bed boiler, wherein bed ash discharged from a furnace bottom of a fluidized bed boiler is pulverized into fine powder, and fly ash collected from a flue is obtained. The present invention relates to a bed ash treatment method for a fluidized-bed boiler, which is mixed with ash.

[0009]

FIG. 1 is a system diagram of an ash processing apparatus for a fluidized-bed boiler according to an embodiment of the present invention. In the figure, reference numeral 4 denotes a classification device connected to the rotary valve 3b;
Is a pulverizer connected to the classifier via a transport pipe 7a, and 6 is a blower for conveying air. 7b is a pipe branching from the branch point X at the outlet of the blower 6 and passing through the air flow distribution damper 9a to the classification device 4; 5 outlet piping 7
d and a pipe that joins at the junction Y to reach the junction Z, 7e is a pipe that reaches the junction Z from the fine-grain classification device 4, and 7f is a junction Z.
This is a pipe extending from the top to the fly ash silo 2.
The configuration and operation of the other parts are the same as those of the related art (FIG. 2).

In the present apparatus, when the ash level of the bed ash silo rises above a specified value, the rotary valve 3b is activated and excess bed ash B in the silo is activated.
To the classifier 4. Here, the fine granules are sent to the fly ash silo 2 through the pipes 7e and 7f by the air sent from the blower 6 through the pipe 7b. Larger particles are sent to the crusher 5 via the pipe 7a. Here, the powder is pulverized, discharged as fine particles having a size of about 50 μm or less from the pipe 7 d, and sent to the fly ash silo 2 through the pipes 7 c and 7 f by the air sent from the blower 6. Both the bed ash which was originally fine and the bed ash which has been finely divided by the crusher are mixed into the fly ash in the fly ash silo 2 and are processed in the same manner as the existing fly ash. That is, a part is recycled to the boiler, and excess fly ash is effectively used as a cement material. The dampers 9a and 9b are used for adjusting the amount of air in order to appropriately carry the air of the fine ash.

[0011]

According to the method for treating bed ash of a fluidized-bed boiler of the present invention, bed ash discharged from the furnace bottom of a fluidized-bed boiler is pulverized into fine powder and mixed with fly ash collected from a flue. Therefore, it is possible to stop the conventional dumping of bed ash, to eliminate air pollution generated at the time of dumping, and to effectively use it for cement materials and the like.

[Brief description of the drawings]

FIG. 1 is a system diagram of an ash processing device of a fluidized-bed boiler according to one embodiment of the present invention.

FIG. 2 is a system diagram of a conventional ash treatment device for a fluidized-bed boiler.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bed ash silo 2 Fly ash silo 3a, 3b Rotary valve 4 Classifier 5 Crusher 6 Blower 7a-7f Piping 8a, 8b Rotary feeder 9a, 9b Air volume distribution damper 10 Transport vehicle 11 Dumping place

Claims (1)

[Claims] 1. A bed ash treatment method for a fluidized bed boiler, comprising crushing bed ash discharged from the furnace bottom of a fluidized bed boiler into fine powder, and mixing the ash with fly ash collected from a flue. .