Solid material comminution or disintegration – Processes – With application of fluid or lubricant material
Reexamination Certificate
1999-07-12
2001-01-30
Rosenbaum, Mark (Department: 3725)
Solid material comminution or disintegration
Processes
With application of fluid or lubricant material
C241S056000, C241S057000, C241S069000, C241S079100, C241S097000, C241S275000
Reexamination Certificate
active
06179231
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method and apparatus for comminuting solid particles and more particularly to such a method and apparatus which utilizes pressurized gas to drive the particles upwardly in a chamber through rotors and rotating semipermeable screens which perform the comminuting action.
2. Description of the Related Art
Micronized limestone is used in agriculture, industrial fillers, environmental controls and the construction trade. Micronized cement is useful in the building industry.
Micronized coal is used as an energy source in the generation of electricity and micronized limestone/dolomite or lime are used for environmental compliance in the flue gas cleanup of power plants. Micronized coal burns with a flame velocity similar to natural gas or fuel oil and with a short flame that allows the heat energy generated in the combustion to be readily transferred to the water walls of the boiler. This results in an increased boiler rating and less heat losses through the ducts and flue stack. In addition to providing a more complete combustion, the micronized coal upon combustion yields a micronized fly ash with low carbon content which is of considerable value in the construction industry as a substitute for cement in high strength concrete formulations.
In addition the combustion of micronized coal requires no excess air and results in minimized NOx in the flue gases. Micronized limestone, dolomite or hydrated lime are most valuable in the dry hot scrubbing of flue gases and affords a more effective aqueous scrubbing thereof as these particles have much larger reactive surfaces for the SOx and NOx scrubbing. This results in a more complete utilization of the sorbents resulting in substantial savings in the flue gas clean up section of a power plant in conforming to the requirements of the Clean Air Act.
The use of micronized coal and limestone/dolomite or lime as the fuel for generating electric power thus has significant advantages over the use of conventional fuels such as fuel oil or non-micronized coal and is much less expensive than natural gas.
In my U.S Pat. No. 5,695,130 issued Dec. 9, 1997, a grinding system is described in which rotating screens with wide mesh openings are first used to comminute particulate material through spiral vortexes and such comminuted material is then fed to circular vortexes formed between rotating discs and stationary plates where the final grinding of the particulate material is accomplished and the final comminuted material is separated from the gas streams by centrifugal fans. The system and method of the present invention applies the basic technology of my prior patent in implementing the micronization of solid particles such as coal, limestone/dolomite, lime, and cement. The system of the present invention provides an improvement over the system of my prior patent in minimizing the erosion of the fan blades employed and lowering the system power requirements.
SUMMARY OF THE INVENTION
The device and method of the present invention achieves the above indicated improvements by providing a pressurized air drive for driving the particles upwardly along with high apex flow enhancers so that a fan for achieving this end result is not required and designing the rotors with short arms so that they do not impact on the particles but rather generate kinetic energy in the form of centrifugal vortices in the air stream.
In the system of the invention, pressurized air is fed into the bottom of a chamber into which the particles to be comminuted are fed. Uplift action is provided by means of a stationary velocity head in the form of an inverted semi-ellipsoidal tank. The particles are first comminuted by a series of short arm rotors designed to generate centrifugal vortices in the uplifting air which effect the comminuting action. Such short arm rotors have the advantages of minimizing wear and tear on the rotor blades and enabling higher operation efficiency since the particles are driven outwardly by the centrifugal force generated in the air stream and tend not to impact on the rotor blades. Further, with shorter arm rotors, the fluid bed volume is expanded. Flow enhancers in the form of vertical apex elements mounted on the inner walls of the chamber enhance the flow of gas along the walls of the chamber. The particles are then passed through a series of semi-permeable rotating screens which further effect the comminuting action. The fully comminuted particles are then driven out of the chamber to a collecting cyclone by the gas stream.
It is therefore an object of this invention to provide a system and method for comminuting particles which consumes less power and results in less wear on the fan blades employed.
It is a further object of this invention to provide a system and method for comminuting particles having higher operation efficiency;
Other objects of the invention will become apparent in view of the following description taken in connection with the accompanying drawings.
REFERENCES:
patent: 293047 (1884-02-01), Mackey
patent: 911913 (1909-02-01), Snyder et al.
patent: 1524651 (1925-02-01), Hapgood
patent: 2752097 (1956-06-01), Lecher
patent: 3690571 (1972-09-01), Luthi et al.
patent: 5280857 (1994-01-01), Reichner
patent: 5695130 (1997-12-01), Csendes
patent: 5826807 (1998-10-01), Csendes
patent: 5850977 (1998-12-01), Csendes
Rosenbaum Mark
Sokolski Edward A.
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