Separation device for unburned carbon in fly ash and...

Solid material comminution or disintegration – Processes – By operations other than force of contact with solid surface

Reexamination Certificate

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C241S005000, C241S026000, C241S039000, C241S284000

Reexamination Certificate

active

06708909

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is a device for separating unburned carbon in fly ash and a separation method for the same. In particular, the present invention pertains to a device which lowers unburned carbon content in aggregated fly ash particles by separating the particles, and refining the particles into smaller sizes for later use.
2. Description of the Related Art
Referring now to
FIG. 4
, in a coal fired power plant (not shown), coal is pulverized in a pulverizing device
40
to an average particle size of roughly 15-40 micrometers (&mgr;m). The coal is then mixed with air at an entrance to a boiler (not shown), where it is burned inside a combustion chamber
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linked to pulverization device
40
. In addition to the carbon content in the coal (fuel), there is approximately 5-30 weight % of ash material. Typically, the ash material is not burned in the above process but is discharged as an undesirable waste product called coal ash at multiple process positions, as will be described.
The components of the discharged coal ash are approximately 40-60 weight % silicon oxide, 20-30 weight % aluminum oxide (alumina oxide), 5-10 weight % calcium oxide, 3-8 weight % iron oxide, 2-10 weight % unburned carbon, and other minor particles. Depending on the origin of the coal used, the discharged coal ash may be alternatively classified as clinker ash, cinder ash, or fly ash. The components of each substance vary slightly due to original composition and processing.
Clinker ash is collected from a boiler furnace bottom part
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positioned below combustion chamber
41
, and is typified as a solid glass-type material. The clinker ash is thereafter pulverized and discharged in a conveniently handled size of approximately 0.5-1 millimeters (mm) (500-1000 &mgr;m). Clinker ash comprises approximately 10-20% of the ash or coal ash waste.
Cinder ash is ash that falls into a fuel economizer
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positioned down-process from combustion chamber
41
. The cinder ash is collected as spherical particles having an average particle size of 30-70 micrometers (&mgr;m) or as aggregates of these spherical particles. Cinder ash comprises approximately 5% of the ash.
Fly ash is ash collected in an electric precipitator
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positioned down-process from fuel economizer
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. Fly ash is collected as spherical particles of average particle size 10-30 micrometers (&mgr;m) or as aggregates of the spherical particles. Fly ash comprises approximately 70-80% of the ash.
Cinder ash and fly ash, are liquefied in air during formation by the heat of combustion, and thereafter cool to form typically spherical particles. These typically spherical particles of cinder ash and fly ash, have an average particle size of 10-70 micrometers (&mgr;m) or may form as aggregates of these particles.
It should be understood from the above, that unburned carbon typically adheres to the pseudo-spherical particles of the ash component or is mixed in independently.
Unfortunately, a large amount of fly ash is discharged as undesirable waste in landfills increasing costs, consuming space, and forming industrial waste.
Even where fly ash with a high unburned carbon content is later used as a clay substitute material in cement, there is a limit to the amount that can be consumed in this manner. Ultimately, a large amount of fly ash must still be disposed of in landfills. Fly ash with low unburned carbon content and small particle size may be used as an admixture for ready-mixed concrete, also within a useful limit. In sum, while there are some uses for the fly ash, the demand is insufficient for the supply and undesirable waste results.
Even if new uses are developed, the particle size, color, and particularly the residual carbon amount and the variability of each of these items make their uniform efficient utilization both difficult and costly. Due to these variabilities, it is difficult to develop new uses for fly ash as a raw material. In sum, it is essential to reduce the unburned carbon content to a preferable and controllable range and so use the fly ash as a new raw material.
Many methods have been attempted to classify the unburned carbon content of ash, including, sieve classification, electrostatic classification, wet classification, vibration classification, jet mill classification. Each has an advantage and a disadvantage but none has been used in common practice or with great success.
Among these methods, a jet mill (or fluid energy mill), in which classification is conducted after fly ash particles collide with each other and pulverized, has been gathering interest. Unfortunately, jet mills have multiple problems. These problems include complex construction, difficult maintenance, and high costs, and difficulty in simple classification, each serving as a barrier to implementation.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to overcome the concerns listed above in a useful and inexpensive manner.
It is another object of the present invention to provide a separation device for unburned carbon that has a simple construction and can easily and effectively separate and remove unburned carbon in fly ash.
It is another object of the present invention to provide a separation method employing the device.
It is another object of the present invention to provide an unburned carbon separation device and a separation method in which abrasion on the apparatus is minimized, powder classification can be easily adjusted according to an input powder, and maintenance is easy and inexpensive.
Briefly stated the present invention is a separation device which includes a casing and a first and a second rotation blade. A pulverization chamber is defined between the casing, the first, and the second rotation blade. Operating a suction device and the first and the second rotation blades, creates channeling vortices within the pulverization chamber. Fly ash containing unburned carbon is fed into the pulverization chamber, and through repeated self-collision, unburned carbon is segregated and reduced in size while remaining particular matter is similarly segregated and reduced in size. A method employs the device and provides simple separation and segregation.
According to the present invention there is provided a separation device, comprising: a casing, the casing includes an inlet for receiving a first material containing at least an unburned carbon portion into the casing, first means for separating the first material into the unburned carbon portion and a second portion, the first means includes second means for reducing in size the unburned carbon portion into a first reduced-size portion and the second portion into a second reduced-size portion, the first means in the casing, and segregation means for receiving the first reduced-size portion and the second reduced-size portion from the casing and segregating the first reduced-size portion from the second reduced-size portion for later use whereby the separation device operates economically and effectively.
It is to be understood, that untreated fly ash is mainly, but not solely, a mixture of silicon oxide particles, aluminum oxide particles, and unburned carbon particles.
According to another embodiment of the present invention, there is provided a separation device, comprising: at least one of the first means, the second means and the segregation means being adjustable according to at least one of a size, a density, and an unburned carbon content of the first material whereby the separation device operates economically and accommodates material variation in the first material.
According to another embodiment of the present invention, there is provided a separation device, comprising: a first rotation blade in the first means, the first rotation blade having a first rotation axis, a second rotation blade in the first means, the second rotation blade having a second rotation axis, the first rotation blade opposing the second rotation blade in the casing along a common axis of rotation, and a pulverization chamber def

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