Patent Application
20170122554
This invention relates generally to electrical generation systems and more particularly to systems that utilize coal.
Coal is by far the most cost effective method for producing electricity. In the United States the material (coal) is abundant and easily obtained relative to the many other sources of fuel. The major problem with coal has been the polluting characteristics of coal; but, generally, it is not the coal that pollutes but rather the contaminates within the coal that are released when the coal is burned. This includes sulfur, mercury, silica and others.
Further, contaminates also increase the cost of energy production by wearing on the electrical generators and associated mechanisms, which shortens their productive lives. As example, sand and silica within the coal abrade the piping and collect on the heat exchangers, thereby reducing the effectiveness of the heat exchangers requiring increased coal consumption to generate the same electricity.
To address this problem, there have been a variety of techniques developed which are used to remove contaminates, but these techniques in-and-of-themselves can generate pollutants when the technique uses water or chemicals in the process.
It is clear there is a need to improve the purity of coal used in the generation of electricity
The invention produces a mechanism and method to clean coal of pollutants and contaminates for more efficient use in a coal fired electrical generator.
Coal generators are well known to those of ordinary skill in the art and include those described in: U.S. Pat. No. 5,003,891, entitled “Pulverized Coal Combustion Method”, issued to Kaneko et al. on Apr. 2, 1991; and, U.S. Pat. No. 3,971,639, entitled “Fluid Bed Coal Gasification” issued to Matthews on Jul. 27, 1996; both of which are incorporated hereinto by reference.
In the process of this invention, the mined coal is first ground to a chosen mesh size. It has been found that a size of between 10-100 mesh is optimal although other mesh sizes can be employed in this context.
Grinding or milling of materials is well known to those of ordinary skill in the art, including, but not limited to those described in U.S. Pat. No. 4,597,537, entitled “Vertical Mill” issued to Misaka et al. on Jul. 1, 1986; U.S. Pat. No. 5,987,966, entitled “Device for Measuring the Quantity of Coal in a Ball Grinder” issued to Fontanille et al. on Nov. 23, 1999; and U.S. Pat. No. 6,138,585, entitled “Clinker Grinder Seal in Coal-Burning Utility Electrical Power Generation Plant” issued to Racine on Oct. 31, 2000; all of which are incorporated hereinto by reference.
The now sized coal, with contaminates, is subjected to a vertical separator which separates pollutants and contaminates from the coal. The vertical separator uses air motion to separate the coal from contaminates based upon the specific gravity of the two. Although this separation is not absolute, it does remove the vast majority of the contaminates which greatly increases the effectiveness of the coal, improves the life of the generator mechanisms, and reduces the amount of contaminates being released during the burning of the coal.
Those of ordinary skill in the art readily recognize a variety of vertical separators which may be used in this context, including, but not limited to that described in: U.S. Pat. No. 9,073,087, entitled “Injector Mechanism” issued to Abbott on Jul. 7, 2015; and, U.S. Pat. No. 5,103,981, entitled “Particle Separator/Classification Mechanism” issued to Abbott et al. on Apr. 14 1992; both of which are incorporated hereinto by reference.
For use in a coal-fired electrical generator, the now cleaned coal is ground to a smaller mesh size and injected, via an airstream, into the boiler of the electrical generator. The removed contaminates, being solid in nature, are easily collected and disposed properly.
In some embodiments, the above process uses a series of vertical separators which are each adjusted to address different mesh ranges. In this embodiment, the ground coal with contaminates are passed over a series of separators/screens in a cascading approach. Coal/contaminates which do not fall through the screen of a first separator fall onto the screen of the second separator; coal/contaminates that don't fall through the screen of the second separator, pass to the third separator, etc., until at the end, the excess is returned to the grinder once more.
In this manner, the grinding process does not have to be as controlled allowing the grinder to perform a “general” grind.
In some embodiments, the clean coal is not to be used on site by an electrical generator, but rather, is to be used at a remote generator, even one in a foreign country. In this case, the ground clean coal is difficult to transport when in the mesh size discussed above. For transportation, in these situations, the clean coal “dust” is formed into solids, ideally of at least four cubic inches, which allow the clean coal to be easily transported. Upon arriving at the remote electrical generator, the coal can be easily ground into the size appropriate for that generator.
Those of ordinary skill in the art readily recognize a variety of mechanisms which can be employed to create solids from coal particles, including, but not limited to those described in: U.S. Pat. No. 5,762,656, entitled “Dense Core Charcoal Briquet” issued to Burke et al. on Jun. 9, 1998; U.S. Pat. No. 8,377,153, entitled “Densified Fuel Pellets” issued to Kluko on Feb. 19, 2013; and U.S. Pat. No. 9,096,810 entitled “Method for Producing a Bio-Coal” issued to Hung et al. on Aug. 4, 2015; all of which are incorporated hereinto by reference.
The invention together with various embodiments will be more fully explained by the accompanying drawings and the following descriptions thereof.
In this embodiment, coal from coal bin 10 (being mined coal) is ground using grinder 11 to form a first ground coal. In this embodiment, grinder 11 is adapted to output ground coal within a chosen particle size range.
This ground coal is communicated to a vertical separator 12 such as those described above to separate the first ground coal into a clean ground coal 13B and contaminants 13A. Contaminants 13A collect 14, are then removed to be disposed according to their toxicity .
The clean ground coal 13B is communicated via duct 16 to a second grinder 15 which grinds the clean ground coal into a second coarseness suitable for use by the coal generator furnace 19. The second clean ground coal is mixed 18 with an air flow 17 prior to being injected into furnace 19.
In the preferred embodiment the operation of
As with the embodiment described above, the ground coal is separated using a vertical separator 22 which communicates the clean ground coal via duct 21 to pelletizer 20. In this embodiment, the clean ground coal is to be used off-site requiring transportation, which, in the ground state, would be problematic; but, as “chunks” of at least four cubic inches, is safely and easily transported.
The clean ground coal is then formed into a solid form using pelletizer 20 which creates solids of at least four cubic inches for ease in transportation. The solid formed clean coal is dropped 24 into railroad car 23 for transportation to the coal fired electrical generator (not shown) where the solid formed clean coal is then ground in situ to the size used for that specific genertor.
In the ideal embodiment of this technique, the clean ground coal is formed into pellet shapes.
The mined coal is stored in bin 30 which feeds grinder 31, grinding the mined coal into a variety of mesh sizes. Grinder 31 feeds the ground coal onto a first separation mechanism 32A which allows a specified mesh size to fall through to vertical separator 34A (not shown). Coal which is not withdrawn from separation mechanism 32A, cascades onto separation mechanism 32B (feeding vertical separator 34B, not shown); the excess coal from separation mechanism 32B cascades onto separation mechanism 32C which allows a certain mesh size to fall to vertical separator 34C, not shown; and the process continues until the final separation mechanism 32N feeding vertical separator 34N.
Any coal not removed via the cascade above, is collected and fed back via duct 33 to the coal bin 30.
In this manner, a less than perfect grinder 31 is able to obtain clean coal as outlined above.
In one application, the clean coal generated by vertical separators 32A-32N is compacted to form the clean ground coal into solids having at least four cubic inches of clean ground coal as described above
It is clear that the present invention provides a highly improved purity of coal to be used in the generation of electricity
