JPH09178149A - Coal ash fluidized bed combustion apparatus and powder mixture supply apparatus in coal ash containing non-combusted component reducing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve means constitution to apply a preprocessing for mixing a combustion improver upon again combustion processing non-combusted fraction leaving coal ash to increase a combustion component. SOLUTION: Coal ash supply means 22 communicating with a fluidized bed combustion furnace 1 includes storage means for separating and storing coal ash 12 and a combustion improver, conveyance means and metering means for individually performing quantitative metering, and powder adjusting means for mixing the coal ash and the combustion improver in a predetermined quantity ratio. Herein, the storage means is a coal ash silo 221 and a solid fuel powder silo 222, and the conveyance means and the metering means are a delivery conveyor 223 and a metering hopper 224, and the powder adjusting means is a mixer 225. Further, the supply means 22 has an independent apparatus construction, and is useable as a powder mixture supply apparatus Y associated with various fluidized bed combustion furnaces taking powder as materials to be processed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unburned component content that is self-combusted by supplementing combustion components when the unburned component (carbon) remaining in the coal ash discharged from a pulverized coal combustion boiler is burnt again. Coal ash fluidized bed combustor in an unburned coal ash unreduced content system for reducing coal and improving it so that it can be used as a good cement admixture, and a powder having an independent device configuration as an object to be treated. The present invention relates to a powder mixture supply device capable of cooperating with various fluidized bed combustion furnaces.

[0002]

2. Description of the Related Art Coal ash discharged from a pulverized coal combustion boiler has been approved for use as a cement admixture.

However, since coal ash obtained by burning general pulverized coal has an unburned content of 3 to 6%, the amount of adsorbed methylene blue which deteriorates the quality of the cement admixture increases, and the cement admixture remains as it is. When used as a material, there is a problem that the air entrainment material (AE material) mixed in the cement is adsorbed by the unburned components, making it difficult to control the air amount.

Therefore, at present, this coal ash is
Are processed in the manner shown in FIG. Landfill. Classifying with a separator to remove high unburned coal ash particles and reduce the overall unburned content to improve the quality of cement admixture. Coal with good flammability is used to prevent the generation of residual unburned matter and reduce the content of unburned matter in coal ash to reform it into a high quality cement admixture.

[0005]

However, the above-described conventional processing has the following problems (a) to (c). (B) There is a limit to the amount of waste that can be landfilled, and unused coal ash becomes useless waste. (B) In order to remove high unburned coal ash particles by classifying with a separator, an expensive separator and time (man-hour) for classifying are required. (C) The use of coal having good combustibility increases the operating cost of the boiler.

Under these circumstances, the present inventors have conducted researches on high quality (reforming) in order to effectively utilize a large amount of coal ash discharged from a coal-fired power plant. Then, we have developed a new combustion method using a fluidized bed combustion furnace to reduce the unburned matter remaining in the coal ash. This result has been previously proposed by the present applicant as "a method for reducing unburned content of coal ash and a coal ash fluidized bed combustion furnace" (Japanese Patent Application No. 7-57948; prior art).

However, in practice, the unburned content is 2-3%.
There is a case where coal ash of a certain degree is handled, and the unburned-content residual coal ash of such a degree cannot obtain a sufficient calorific value at the time of combustion (small) only by the technology of the prior application, so the furnace temperature is set to 650 to 850 ° C. It became difficult to maintain, and the desired low unburned coal ash could not be obtained.

[0008] From this, the unburned component content is 5 to 6% by adding and mixing the auxiliary combustion material before charging into the combustion furnace.
A pretreatment (mixing step) for preparing powder so as to obtain an object to be treated corresponding to a degree of coal ash was requested. That is,
This is the development of a coal ash fluidized bed combustor in which the coal ash supply means is modified so as to perform a pretreatment in which the material to be treated is a mixture in order to supplement the combustion components.

Here, the modified coal ash supply means has an independent device structure and can be separated from the coal ash fluidized bed combustion apparatus, and the powder is used as a mixture supply means for preparing the powder. Considering the case of a powder mixture supply device capable of cooperating with various fluidized bed combustion furnaces.

[0010]

In order to solve the above-mentioned problems, the present invention is directed to a device for reducing unburned content of coal ash, which is configured to perform a pre-treatment in which an object to be treated is a mixture in order to supplement combustion components. A coal ash fluidized bed combustion device in a system,
The coal ash supply means is a storage means for separately storing the coal ash and the auxiliary combustion material, a conveying means and a metering means for individually delivering a fixed amount, and a predetermined amount ratio of these coal ash and the auxiliary combustion material. And a powder preparation means for mixing in 1.

Here, the storing means is a coal ash silo and a solid fuel powder silo, the conveying means and the measuring means are a payout conveyor and a measuring hopper, and the powder preparing means is a mixer.

Further, there is provided a powder mixture supplying device for preparing and supplying the powder to be processed and the auxiliary material in a fluidized bed combustion furnace in which the powder is to be processed, at a predetermined ratio. A storage means for separating and storing the powder to be treated and the auxiliary material, a conveying means and a metering means for individually delivering a fixed amount, and a predetermined amount ratio of the powder to be treated and the auxiliary material. And a powder preparation means for mixing in 1.

Here, the powder to be treated is unburned residual coal ash, etc., the combustion improver is solid fuel powder such as coal powder, heavy duty ash, etc., and the storage means is a coal ash silo and solid fuel powder. A silo for use, a conveying means and a measuring means are a delivery conveyor and a measuring hopper, and a powder preparing means is a mixer.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In a coal ash fluidized bed combustion apparatus in a coal ash content unburned content reducing apparatus system of the present invention, coal ash supply means is constituted by a plurality of constituent elements, and coal ash and solid fuel powder are mixed. Storage means for separating and storing, a transporting means and a weighing means for individually delivering a fixed amount, and a powder preparation means for mixing the coal ash and the solid fuel powder at a predetermined ratio. In order to supplement the combustion components to carry out a pretreatment step of mixing the material to be treated, the storage means is a silo for coal ash and a silo for solid fuel powder, respectively, the conveying means and The weighing means is a payout conveyor and a weighing hopper, and the powder preparation means is a mixer.

Here, the low content unburned residual coal ash stored in the coal silo and the solid fuel powder stored in the solid fuel powder silo are individually fed to the mixer through the delivery conveyor and the weighing hopper. The mixture is sent and prepared at a predetermined mixing ratio, and is supplied into the coal ash fluidized bed combustion furnace as a mixture in which combustion components (calorific value) are augmented.

In a coal ash fluidized bed combustion furnace, the above mixture (object to be treated) is charged on a perforated plate in the furnace and preheated by a combustion means to a self-combustion temperature range (650 to 850 ° C.),
The supporting gas is supplied to the lower side of the perforated plate in the furnace by the supporting gas supply means, the supporting gas is increased from the fine holes of the perforated plate between the particles of the coal ash, and the coal ash is fluidized and burned. The unburned matter remaining in the coal ash by means of 650 to 850
It is self-combusted at ℃ and reformed to low unburned coal ash with a reduced unburned content of coal ash.

The low unburned coal ash thus obtained can be used as a high quality cement admixture with a reduced amount of adsorbed methylene blue.

In addition, the powder mixture supplying device having an independent device configuration includes a storage means for separating and storing the powder to be treated and the solid fuel powder, a conveying means for individually delivering a fixed amount, and It is provided with a measuring means and a powder preparing means for mixing at a predetermined amount ratio, and in a specific embodiment, the object powder is unburned residual coal ash, etc., and the solid fuel powder is The storage means is a coal ash silo and a solid fuel powder silo, the conveying means and the measuring means are a delivery conveyor and a measuring hopper, and the powder preparing means is a mixer.

Then, the material powder to be treated and the solid fuel powder are prepared in a predetermined ratio and supplied as a mixture (object to be treated) supplemented with the combustion component (heat generation amount). Therefore, it is possible to cooperate with various fluidized bed combustion furnaces in which powder is the object to be treated.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a flow sheet for explaining an unburned coal ash unburned matter reducing apparatus system including a coal ash fluidized bed combustion apparatus according to an embodiment of the present invention, and FIG. 2 is a coal ash fluidized bed combustion apparatus. It is a schematic configuration diagram showing a coal ash supply means (or a powder mixture supply device) of the apparatus.

As shown in FIG. 1, the coal ash unburnt content reducing system (Z) is a coal ash supply apparatus capable of preparing a mixture [unburned residue residual coal ash and solid fuel powder] supplemented with combustion components. (2
2), a coal ash fluidized bed combustion furnace (1) which receives this mixture [object to be treated] and combusts in a fluidized (layered) manner, and a low unburnt after combustion treatment discharged from the fluidized bed combustion furnace (1) Fluidized bed cooler (21) for fluidized cooling of residual coal ash, cyclone (23) as a post-treatment means for combustion gas (16) and hot air (15) discharged from these, heat recovery boiler (24), The dust collector (25) and the desulfurization and denitration device (26) are main components.

As shown in FIGS. 1 and 2, the coal ash fluidized bed combustion apparatus (X) is equipped with a coal ash supply apparatus (22) [or a powder mixture supply apparatus (Y)] as a coal ash supply means. This coal ash supply device (22) is composed of a plurality of constituent elements, and separates unburned residual coal ash and solid fuel powder [coal powder, heavy ash, etc.] for storage respectively. Silo for coal ash (221) and silo for solid fuel powder (222) [respective storage means], delivery conveyors (223,223) [conveying means] and weighing hoppers (224,224) [measuring means] for individually delivering fixed amounts ] And a mixer (225) [powder preparation means] for mixing in a predetermined amount ratio.

Since the coal ash supply device (22) has an independent device structure, it can be separated as the powder mixture supply device (Y). [Fig. 2]

The request for the coal ash fluidized bed combustion apparatus (X) having the above-mentioned structure is to set a desired furnace temperature at 650 to 850 ° C. (self-combustion temperature) when processing about 2-3% unburned residual coal ash. The range is that the combustion component is adjusted by pretreatment to maintain the temperature range, and the amount of heat generated during combustion is increased.

Therefore, about 2-3% of unburned residual coal ash and solid fuel powder (supporting material) such as coal powder and heavy duty ash are mixed at a predetermined ratio, and the unburned content ratio is 5 to 5. A coal ash supply means (22) that can be prepared to be a treatment object corresponding to about 6% of coal ash is configured as an apparatus, and the fed treatment object (mixture) is stored in the combustion furnace (1) at 650 to 650. By burning at 850 ° C. (self-burning temperature range of coal ash), the unburned content content in the coal ash is reduced to obtain a low unburned content coal ash with a content rate of about 1% or less. It is a thing.

The treatment process in the coal ash fluidized bed combustion device (X) will be described below.

First, the unburned residual coal ash stored in the coal ash silo (221) and the solid fuel powder stored in the solid fuel powder silo (222) are respectively passed through the payout conveyors (223, 223). The weighing hopper (224,22
4), and is mixed by a mixer (225) in a predetermined ratio.

The mixture prepared here becomes an object to be treated having a calorific value equivalent to that of coal ash having an unburned content of about 5 to 6%.

Then, a perforated plate (2) in the combustion furnace (1) is passed through a coal ash supply pipe (not shown) of the coal ash supply device (22).
The coal ash (12) is preheated (and burned) by being supplied (supplied) to the top and igniting the burner by the preheating device (10).

When the preheating temperature reaches 650 to 850 ° C., the preheating device (10) is stopped to switch to self-combustion, the air (13) is fed from the air supply pipe (6) to the air chamber (3), and ,
It is blown from below the perforated plate (2) to raise the space between the particles of the coal ash (12) and cause the coal ash (12) to flow, and burn (self-burn) the unburned matter remaining in the coal ash (12). .

At this time, the temperature in the furnace (fluidized bed temperature) rises due to combustion heat, but is controlled (temperature control) to 650 to 850 ° C. by dropping and supplying new coal ash. That is, during combustion, the temperature inside the furnace is detected by each thermometer (not shown). If this temperature decreases, the supply amount of air (13) is reduced, and if the temperature rises, the supply amount of air (13) is reduced. To maintain a combustion temperature of 650-850 ° C.
This is a so-called continuous operation in which the temperature inside the furnace is controlled as needed by adjusting the supply of coal ash (12) and air (13).

The air supplied during this operation is preheated air (13
It is a mixture of a) and the outside air (13).

FIG. 3 shows a data plot of fluidized bed temperature and unburned matter content. Here, the unburned component content of 5 to 6% (previously described) before combustion is due to the combustion treatment of 650 to 850 ° C.
It can be confirmed that it decreases to 0.4 to 1.8%.

Low unburned coal ash (12a) rising to the upper fluidized zone in the furnace is taken out (recovered) by changing the discharge position according to the unburned content. It is discharged onto the perforated plate (2 ') in the fluidized bed cooler (21) from the upper discharge pipe (7b) or the lower discharge pipe (7a) provided on the furnace wall.

In the fluidized bed cooler (21), the air (13 ') fed from below the perforated plate (2') is fed from the fine holes (not shown) of the perforated plate (2 ') to a low unburned coal ash. While increasing the number of particles of (12a), the cooling water (14) is circulated in the cooling pipe (5) arranged between the fluidized layers to fluidly cool the low unburned coal ash (12a). Here, the low unburned coal ash (12a) is discharged and collected outside.

Further, the high temperature air (15) discharged from the fluidized bed cooler (21) merges with the combustion gas (16) discharged from the fluidized combustion furnace (1) in the middle of the path to form a mixed exhaust gas (17). , Sent to a downstream cyclone (23).

The cyclone (23) removes low unburned coal ash (12a) in the mixed exhaust gas (17) and discharges it downward. The heat recovery boiler (24) recovers (heat exchanges) the heat of the mixed exhaust gas (17) to preheat the air (13), and at the same time, the cooling water (1
4 ') is heated to generate high temperature water [or steam] (14a).

The preheated air (13a) is supplied to the air supply pipe (6).
It is circulated and used together with the air (13). Further, the high-temperature water [or steam] (14a) is separately used inside or outside the system.

The dust collector (25) collects fine low unburned coal ash (12a) remaining in the exhaust gas (17) and discharges it downward. The desulfurization and denitration equipment contains SO _X , NO _X contained in the exhaust gas (17).
Is removed.

[0041]

EFFECTS OF THE INVENTION The present invention is constituted as described above, and according to the present invention, when treating unburned residual coal ash having an unburned content of about 2 to 3%, a desired furnace temperature is set. 650
In order to maintain the temperature at 850 ° C. (self-combustion temperature range), the combustion component can be adjusted by pretreatment to increase the calorific value during combustion. As a result, it is possible to obtain low unburned coal ash in which good combustion (treatment) is maintained and the unburned content of the coal ash is reduced to about 1% or less. And this low unburned coal ash can be used as a high quality cement admixture.

Further, the coal ash supply device has an independent device configuration separable from the combustion furnace, and the powder mixture supply device can be installed in the fluidized bed combustion furnace in which the powder is the object to be treated. Can be used as

[Brief description of the drawings]

FIG. 1 is a flow sheet illustrating an apparatus for reducing unburned coal ash content including a coal ash fluidized bed combustion apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a coal ash supply means (or a powder mixture supply device) of the coal ash fluidized bed combustion apparatus of the embodiment.

FIG. 3 is a data plot showing a fluidized bed temperature (combustion temperature of coal ash) VS. unburned matter content of a fluidized bed combustion furnace in a coal ash fluidized bed combustion apparatus of an example.

[Explanation of symbols]

 1 Fluidized Bed Combustion Furnace 2; 2'Perforated Plate (Coal Ash Placement Means) 3 Air Chamber 5 Cooling Pipe 6 Air Supply Pipe (Combustion Gas Supply Means) 7a Lower Discharge Pipe (Processed Material Discharge Means) 7b Upper Discharge Pipe ( Processed material discharge means) 10 Preheater (combustion control means) 12 Coal ash (unburned residual coal ash) 12a Low unburned coal ash 13; 13 'Air (flow path) 13a Preheated air (flow path) 14; 14 '' Cooling water (flow path) 14a Hot water (flow path) 15 Hot air (flow path) 16 Combustion gas (flow path) 17 Mixed exhaust gas (flow path) 21 Fluidized bed cooler 22 Coal ash supply device (coal ash supply means) 221 Coal ash silo (storage means) 222 Solid fuel powder silo (storage means) 223 Discharge conveyor (transportation means) 224 Weighing hopper (measurement means) 225 Mixer (powder preparation means) 23 Cyclone 24 Heat recovery boiler 25 Dust collection 26 Desulfurization and denitration equipment X Coal ash fluidized bed combustion equipment Y Powder mixture supply equipment Z Coal ash Unburned reducing device system

Claims (4)

[Claims] 1. An apparatus for reducing unburned content of coal ash for reducing the content of the unburned content remaining in the coal ash by burning it again is included in the combustion furnace body and installed in the bottom of the furnace. Means for loading coal ash, an air chamber provided below the means for loading coal ash, a combustion-supporting gas supply unit that communicates with this air chamber, a coal ash supply unit that communicates with the outside of the furnace, and a coal ash. Coal ash provided with combustion control means for holding the temperature in the furnace during fluidized combustion including preheating after charging in the self-combustion temperature range of coal ash, and treated material discharge means provided in multiple stages on the furnace wall in the upper fluidized zone In the fluidized bed combustion apparatus, the coal ash supply means includes a storage means for separating and storing coal ash and an auxiliary combustion material, a transportation means and a metering means for individually delivering a fixed amount, and the coal ash and the auxiliary combustion. A powder preparation means for mixing the material with a predetermined amount ratio In addition, a coal ash fluidized bed combustor in a system for reducing unburned content of coal ash, characterized in that a pretreatment is carried out using a material to be treated as a mixture in order to supplement the combustion components. 2. The coal ash according to claim 1, wherein the storing means is a coal ash silo and a solid fuel powder silo, the conveying means and the measuring means are a delivery conveyor and a measuring hopper, and the powder preparing means is a mixer. Coal ash fluidized bed combustor in a system for reducing unburned carbon content. 3. A powder mixture supply device for preparing and supplying powder to be processed and combustion-supporting material in a predetermined ratio to a fluidized bed combustion furnace using powder as a material to be processed. A storage means for separately storing the material powder and the auxiliary combustion material, a conveying means and a metering means for individually delivering a fixed amount, and the processing target powder and the auxiliary combustion material are mixed at a predetermined amount ratio. A powder mixture supply device, comprising: 4. The to-be-treated powder is unburned residual coal ash, etc., the combustion improver is coal powder, heavy fuel ash or other solid fuel powder, and the storage means is for coal ash silo and solid fuel powder. A silo, a conveying means and a weighing means are a delivery conveyor and a weighing hopper, and a powder preparation means is a mixer.
The powder mixture supply device described.