METHODS AND SYSTEMS FOR STORAGE OF RENEWABLE ENERGY SOURCES IN INCREASED ENERGY DENSITY COAL

Abstract

Methods and systems for reducing carbon dioxide emissions from a coal-fired power plant by using thermal energy from a non-carbon source to reduce the amount of electrical energy needed to reduce the moisture content of coal and increase the energy density of coal prior to combustion are provided. The system includes at least one non-carbon thermal energy source; a coal processing plant configured to reduce the moisture content of coal and produce an increased energy density beneficiated coal, wherein said at least one non-carbon thermal energy source is used to reduce an electrical need of the coal processing plant; and a coal-fired power plant configured to combust the increased energy density beneficiated coal thereby producing electricity on demand at an increased efficiency with reduced carbon dioxide emissions from the plant. The renewable energy source is selected from microwave, hydroelectric power, solar power, wind power, and/or wave power.

Claims

1. A system for reducing carbon dioxide emissions from a coal-fired power plant by using electrical energy from a renewable electricity source to reduce the amount of electrical energy needed to increase the energy density in a beneficiated coal comprising: at least one renewable electricity energy source; a coal processing plant, wherein the renewable electricity source is configured to power a coal beneficiation process; and a coal-fired power plant configured to combust the increased energy density beneficiated coal thereby producing electricity on demand at an increased efficiency with reduced carbon dioxide emissions from the plant.

2. The system of claim 1 wherein the renewable electricity source is selected from hydroelectric power, solar power, wind power, wave power and combinations of the foregoing.

3. (canceled)

4. The system of claim 1 wherein a location of the coal processing plant is selected from a coal mine, a coal transportation terminal, a coal-fired power plant, a same site as the non-carbon thermal energy source and combinations of the foregoing.

5. The system of claim 4 wherein the coal transportation terminal is selected from terminals providing access to a ship, barge, rail, truck and combinations of the foregoing.

6. The system of claim 1 wherein the coal processing plant is integrated with a coal-fired power plant and shares use of coal handling, coal crushing and coal conveying equipment.

7. The system of claim 1 wherein said increased energy density coal is configured to be stored, transported and later combusted to produce said electricity on demand.

8. (canceled)

9. The system of claim 1 in which the coal processing plant is configured to convert electrical energy to microwave energy to reduce the moisture content of the coal.

10.-12. (canceled)

13. A system to store electricity from a renewable electricity source by using the electricity to power in a coal processing plant to decrease the moisture content of coal resulting in an increased energy density beneficiated coal that can be subsequently combusted to produce electricity on demand comprising: a coal processing plant; at least one renewable electricity source configured to input energy into a coal beneficiation process in the coal processing plant to produce the increased energy density coal that stores the inputted renewable electricity; and a coal-fired power plant configured to convert the stored renewable electricity in the increased energy density coal to electricity on demand.

14. The system of claim 13 wherein the at least one renewable electricity source is selected from hydroelectric power, solar power, wind power, wave power and combinations of the foregoing.

15. The system of claim 13 wherein a location of the coal processing plant is selected from a coal mine, a coal transportation terminal, a coal-fired power plant, a same site as the renewable electricity source and combinations of the foregoing.

16. The system of claim 15 wherein the coal transportation terminal is selected from terminals providing access to a ship, barge, rail, truck and combinations of the foregoing.

17. The system of claim 13 wherein the coal processing plant is integrated with the coal-fired power plant and shares use of coal handling, coal crushing and coal conveying equipment.

18. The system of claim 13 wherein said increased energy density coal is configured to be stored, transported and subsequently combusted to produce said electricity on demand.

19. The system of claim 13 wherein said at least one renewable electricity source is configured to preheat the coal prior to processing.

20.-30. (canceled)

31. The system of claim 2 wherein the solar power is selected from photovoltaic panels or a concentrated solar thermal system to produce the electrical energy.

32. The system of claim 1 where the coal beneficiation process involves reducing a moisture content of the coal to increase an energy density of the coal.

33. The system of claim 32 wherein the coal beneficiation process is configured to convert electrical energy to mechanical energy to reduce the moisture content of the coal.

34. The system of claim 33 wherein the mechanical energy to reduce moisture content comprises high-pressure compaction.

35. The system of claim 32 wherein the coal processing plant is configured to convert electrical power to microwave energy to reduce the moisture content of the coal.

36. The system of claim 1 wherein the coal beneficiation process further comprises the addition of a halogen to the coal beneficiation process.

37. The system of claim 1 wherein the coal beneficiation process further comprises a removal of sulfur-containing compounds from said coal.

38. The system of claim 1 further comprising a thermal energy source configured to reduce a quantity of the electrical energy necessary to power the beneficiation process.

39. The system of claim 38 wherein the thermal energy is selected from fossil fuel combustion, waste energy, and combinations of the foregoing.

40. The system of claim 39 wherein the waste energy is selected from waste heat and/or low-quality steam generated from a power plant or industrial process.

41. The system of claim 13 wherein the solar power comprises either photovoltaic panels or a concentrated solar thermal system to produce the electrical energy.

42. The system claim 13 wherein the coal beneficiation process converts electrical energy to mechanical energy to reduce the water content of the coal.

43. The system of claim 42 wherein the mechanical energy to reduce the water content of coal comprises high-pressure compaction.

44. The system of claim 43 wherein the coal processing plant is configured to convert electrical power to microwave energy to remove moisture from the coal.

45. The system of claim 13 further comprising a thermal energy source to supplement the renewal electricity source and configured to reduce a quantity of electrical energy necessary to beneficiate the coal.

46. The system of claim 45 wherein the thermal energy is selected from fossil fuel combustion, waste energy, and combinations of the foregoing.

47. The system of claim 46 wherein the waste energy is selected from waste heat and/or low-quality steam generated from a power plant or industrial process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] FIG. 1 is an illustration of one configuration of the invention.

[0047] FIG. 2 is an illustration of an alternative configuration of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0048] There are a number of known coal beneficiation processes in the art, e.g. those as described in U.S. Pat. No. 3,999,958; U.S. Pat. No. 4,252,639; U.S. Pat. No. 4,397,248; U.S. Pat. No. 4,412,842; U.S. Pat. No. 4,632,750; U.S. Pat. No. 4,702,824; U.S. Pat. No. 6,632,258; U.S. Pat. No. 7,901,473; U.S. Pat. No. 8,585,788; U.S. Pat. No. 8,579,998; U.S. Pat. No. 8,647,400; and U.S. Pat. No. 8,925,729, the disclosure of each of which is incorporated by reference in their entirety. However, each of these processes has inherent limitations in that the coal beneficiation processes described therein are not integrated with a renewable energy source so that the net overall environmental impact of such coal beneficiation processes is limited, principally that such coal beneficiation processes require an enormous amount of energy supplied by carbon generating sources such that even if the end result is a more energy-dense coal product, the net benefit on environmental impact is reduced or even minimalized in many circumstances.

[0049] An alternative to coal-fired power generation that does not result in emissions of carbon dioxide is the use of renewable energy sources such as wind, solar, and hydroelectric energy. However, these sources, while clean, are intermittent and subject to seasonal, daily, and instantaneous fluctuations in generation. Thus, they cannot be depended upon for a continuous source of electricity to meet demand.

[0050] A solution to this issue of intermittency of renewable generation is to use energy storage systems, such as batteries, compressed and/or liquid air systems, and pumped hydro systems (distinct from hydroelectric energy sources used in the present invention). These systems are limited in all practicality to short-term storage, such as batteries that are only capable of storing energy for a few minutes to a few hours, or they suffer from significant energy loss and inefficiency. For example, liquid air systems operate at significantly less than 80% efficiency, leading to large losses of energy during storage. The present invention solves this technical problem by integrating renewable energy sources with coal beneficiation processes to reduce the overall environmental impact of the coal-processing plant and to provide consistent energy sources in the form of beneficiated coal. Integrating renewable energy sources with coal beneficiation processes has a number of distinct potential advantages over the prior art, including advantages over standalone renewable energy sources and other stored energy systems.

[0051] Some of the advantages are as follows. Integrating renewable energy sources with coal beneficiation processes allows for grid level storage and generation of dispatchable energy. In many circumstances, renewable energy sources as stand-alone sources of energy provide insufficient power output for urban cities and other major population centers, especially in the developed and developing world. Beneficiated coal is capable of being produced in an amount to produce hundreds to thousands of megawatts (MWs) of electrical power. For example, beneficiated coal may be produced in an amount sufficient to power a 5 MW rated plant, a 10 MW rated plant, a 25 MW rated plant, a 50 MW rated plant, a 75 MW rated plant, a 100 MW rated plant, a 125 MW rated plant, a 150 MW rated plant, a 175 MW rated plant, a 200 MW rated plant, a 225 MW rated plant, a 250 MW rated plant, a 275 MW rated plant, a 300 MW rated plant, a 325 MW rated plant, a 350 MW rated plant, a 375 MW rated plant, a 400 MW rated plant, a 425 MW rated plant, a 450 MW rated plant, a 475 MW rated plant, a 500 MW rated plant, a 525 MW rated plant, a 550 MW rated plant, a 575 MW rated plant, a 600 MW rated plant, a 625 MW rated plant, a 650 MW rated plant, a 675 MW rated plant, a 700 MW rated plant, a 725 MW rated plant, a 750 MW rated plant, a 775 MW rated plant, a 800 MW rated plant, a 825 MW rated plant, a 825 MW rated plant, a 875 MW rated plant, a 900 MW rated plant, a 925 MW rated plant, a 950 MW rated plant, a 975 MW rated plant, a 1,000 MW rated plant, or plants rated above 1,000 MW, and any intervening ranges therein.

EXAMPLE I

[0052] Assume a base case of a 500 MW coal-fired power plant with a heat rate of 10,500 BTU/kWh burning 2.2 MT/yr of subbituminous coal from the Powder River Basin with a moisture content of 26% and an energy content of 8900 BTU/lb. The power plant generates 1.2 Tons of CO2/MW-hr. By installing a renewable source of electricity, e.g. wind or solar) capable of generating 60 MWs of electricity at a 30% capacity, it will reduce the electricity needed from the power plant by 120,000 MW-hrs each year resulting in a decrease of 143,000 tons of carbon dioxide emitted each year.

EXAMPLE II

[0053] However, by using the system in accordance with the invention, a greater benefit than set forth in Example I could be achieved if rather than putting the renewable electricity directly on the transmission lines, the electricity is instead used to beneficiate/dry coal. Assume the coal beneficiating plant treats all of the 2.2 MT/yr of the coal feeding the base case power plant described in Example I, reducing the moisture content to 13% and thereby increasing the energy content of the treated coal to 9,900 BTU/lb. By using the system in accordance with the invention, the entire output of the 60 MW renewable generation system is provided to the coal beneficiation plant, which represents 50% of the electricity needed to dry the coal with the remainder, 120,000 MW-hrs/yr, coming from the coal-fired power plant. When this coal is burned in the power plant to make electricity on demand, the combination of synergistic effects and increased generation efficiency results in reducing the emissions of carbon dioxide by 516,000 tons/yr. This means that if the electricity generated by the renewable source is used in a coal drying process, it will increase the reduction of carbon dioxide emission by greater than a factor of three compared to using the electricity to reduce the electrical output of the coal power plant as is the current strategy for using renewable electricity.

[0054] The other benefit of the approach described in Example II is that the coal stores the intermittent electricity from the renewable source and, when burned, converts it into a form that can then be used to generate electricity on demand. In addition, unlike other energy storage concepts which suffer from losses of stored energy as it cycles from charging to discharging, the concept disclosed in Example II will result in an increase in energy as the higher density coal is burned to produce electricity on demand. Under the conditions described in Example II, the 120,000 MW-hrs of renewable electricity stored each year would result in an increase of 311,000 MW-hrs of electricity.

[0055] Beneficiated coal can be used immediately after being processed, but it is also capable of storing energy for a significant period of time, for several months up to a year or longer, as opposed to many other stored energy sources such as batteries. For example, beneficiated coal may have a shelf life of at least 1 month, at least 2 months, at least 3 months, at least 4 months, at least 5 months, at least 6 months, at least 7 months, at least 8 months, at least 9 months, at least 10 months, at least 11 months, at least 12 months, at least 13 months, at least 14 months, at least 15 months, at least 16 months, at least 17 months, at least 18 months, at least 19 months, at least 20 months, at least 21 months, at least 22 months, at least 23 months, at least 24 months, or greater than 24 months, and any intervening ranges therein.

[0056] Integrating renewable energy sources with coal beneficiation processes provides for a disconnect between the timing of the energy produced by the renewable energy source and the ultimate timing of the use of the stored energy to satisfy customer demand. This is especially relevant in the case of renewable energy sources such as solar energy and wind energy, which are reliant on natural conditions beyond human intervention. Beneficiated coal is superior to standalone renewable energy sources because it provides a means of storing energy where the rate of release of the stored energy is isolated and independent of the rate of generation of the renewable energy. The storage of energy in beneficiated coal is highly efficient so that most of the energy stored from the renewable energy sources can be recovered when the coal is burned to produce power. Furthermore, it allows the energy storage facility to be located at the source of renewable energy generation and the energy can be used at another location without the need for transmission lines that are expensive and difficult to permit across private property, state and national borders.

[0057] In addition, the beneficiated coal can be shipped across oceans to other countries that are not possible to reach by transmission lines because of cost and practical limitations. The beneficiated coal represents stored energy that can be transported by truck, rail, barge, or ship across a continent, or around the world, to meet consumer demand for power.

[0058] Because of the intermittency of renewable energy sources of electricity, it is necessary that coal-fired plants operate at different loads cycling in responses to instantaneous and diurnal changes in available power renewable power and changes in demand conditions. The cycling of the plant creates operations and maintenance problems for the plant equipment but also results in operating a non-optimal conditions. A coal-fired plant is designed so that highest generation efficiency and lowest CO.sub.2 production per unit of electricity produced occurs at approximately 80% of rated capacity. Therefore, as the plant cycles to lower and higher capacity operating conditions, generation efficiency is reduced and relative CO.sub.2 production increases. With the current invention, it is possible to use the beneficiated coal produced by intermittent energy in a manner to maintain steady operation independent of the timing and variability of the intermittent energy. In this manner, the invention provides a buffering between the two generating sources resulting in lower CO.sub.2 production per unit power produced by operating at more optimum conditions.

[0059] Coal beneficiation processes can be located at the site where coal is mined, at power plants where the coal is converted into energy, or at transportation terminals that feed into multiple different plants. The coal beneficiation process can occur at the site of the renewable energy source as well, or, all four can occur at the same site. This means that at least the following combinations are possible. The coal beneficiation process, the coal power plant, the coal mining, and the renewable energy source can be at four different sites. The coal beneficiation process, the coal power plant, the coal mining, and the renewable energy source can be all at the same site. The coal beneficiation process, the coal mining, and the renewable energy source can all be at the same site, and the coal power plant at a different site. The coal beneficiation process and the coal mining can be at the same site, and the coal power plant and renewable energy source can be at a different site. The coal beneficiation process can be at one site, and the renewable energy source, the power plant, and the coal mining at a different site or sites. The coal beneficiation process, the coal mining, and the renewable energy source can be at a same site and the coal power plant at a different site. The coal beneficiation process and renewable energy source can be at one site, and the coal mine and coal power plant at a different site or sites. The coal mining can be at one site, and the coal beneficiation process, renewable energy source, and coal power plant at a different site or sites. These combinations may be further expanded to one or more additional sites.

[0060] In those embodiments where the coal beneficiation process is integrated with the operation of a coal power plant, i.e. located at the same site as the coal power plant, the coal beneficiation process can be integrated into the operation of the coal power plant in order to further increase the operational efficiency of the coal power plant. For example, waste heat generated from the combustion of coal at a power plant may be used to remove water or supplemental the removal of water from coal prior to combustion. Interfacing the coal beneficiation process between the coal crusher and the pulverizer can save additional energy. This eliminates the need for separate coal crushing in the beneficiation process as well as eliminating the need for briquetting the beneficiated coal.

[0061] Referring now to FIG. 1 one example of integrating a renewable source of energy with coal beneficiation at a coal drying/processing plant is illustrated. Raw untreated coal is delivered by coal transportation system (2) to the coal processing plant (1) where moisture is removed during a coal beneficiation process creating a coal with higher energy density (6) which is then transported (7) to a power plant where it is combusted to generate make dispatchable electricity. The coal processing plant (2) requires both electrical and thermal energy to dry the coal. The electrical energy comes from a combination of electricity from the grid (4) and electricity from renewable sources (3). The thermal energy comes from a fossil-fired combustor (5).

[0062] Referring now to FIG. 2 another example of integrating a renewable source of energy with coal beneficiation at a coal drying/processing plant is illustrated. FIG. 2 illustrates a configuration in which the coal drying/processing plant (8) is integrated closely with a coal-fired power plant (17). Raw untreated coal (14) stored in a pile is conveyed to a coal crusher (15) to reduce the size of the coal, after which conveyer (16) the crushed coal to the coal-fired combustor (17). All or part of the crushed coal is taken off of conveyor (16) and delivered by conveyer (10) to the coal processing plant (8) which dries the coal creating a coal with a higher energy density (18) which is conveyed on belt (19) to conveyer (16) where it is delivered to the coal-fired combustor (17) which burns the coal to generate electricity which is transmitted on wire (11) to the grid. The coal processing plant (8) requires both electrical and thermal energy to dry the coal. The electrical energy comes from a combination of electricity from the grid (12), from the power plant (20), and electricity from renewable sources (9). The thermal energy comes from waste energy from the power plant (17) in the form of heated flue gas, low quality steam, or a working fluid delivered via piping (13) to the coal processing plant (8) where it is used in the drying of the coal.

[0063] Integrating renewable energy sources with coal beneficiation processes are compatible and complementary to the other means of reducing carbon emissions from coal-fired power plants including ultra- and supercritical plants and CCS technologies. In those embodiments where the beneficiation occurs at a coal mine (as discussed supra), such methods will reduce the amount of coal needed to be transported resulting in even further decreases in carbon emissions. As discussed herein, the coal beneficiation process may further comprise additives to the coal, and/or reducing the emissions of particulate matter, sulfur, mercury, and other toxic substances. Additionally, reducing the amount of moisture in the coal will reduce the amount of coal being burned which will improve the operation of several plant systems resulting in reducing the parasitic power needed to run the plant. For example, it will lower the amount of pollutants and the volume of flue gas to be treated by air pollution control (APC) equipment. The reduced amount of coal will reduce the electrical power required to pulverize the coal. The lower volume of combustion gases will also reduce the power required by the fans to move the gases. This will have an added benefit of reducing the pressure difference between the inside of the duct and the outside air resulting in lower in-leakage of air which reduces the efficiency of the plants. All of these reductions in parasitic energy result in a decrease in the amount of CO.sub.2 produced per unit of net electrical power generated by the plant. An additional benefit may be the generation of greater amounts of electricity at a plant that was originally designed for a higher heat content coal. This will allow the power company to optimize how much power is generated from a lower CO.sub.2 emitting plant. The coal which is subject to coal beneficiation may be any type of coal, including peat coal, lignite coal, sub-bituminous coal, bituminous coal, and anthracite, although one of ordinary skill in the art will recognize that coal with higher water content such as sub-bituminous coal will benefit more from beneficiation than lower water content coal such as bituminous coal.

[0064] In some embodiments, the renewable energy source comprises a solar power energy source that produces electricity. Solar power has several distinct advantages and drawbacks. Solar power is totally renewable, and under certain conditions, such as those found in the American Southwest, are capable of generating a large amount of electricity. However, solar energy systems are diurnal and only capable of generating electricity when exposed to sunlight, thus their efficiency is limited. Currently, solar energy is stored in storage devices such as batteries, but as discussed herein such devices are not suitable for long-term storage or for transport. Integrating solar energy into coal beneficiation allows for systems where the solar energy powers the coal beneficiation process to provide a product that is capable of long-term storage and providing consistent output. Additionally, in those locations where solar energy is robust, during the daytime the solar power produced may be in excess of consumer demand at that time, which represents a good opportunity for improved energy production and storage.

[0065] Solar energy is generally categorized as part of a photovoltaic system (solar cells) or concentrated solar power (CSP) used with a steam turbine. Photovoltaic systems are comprised of devices that convert light into electric current using the photovoltaic effect. Efficiency of photovoltaic systems can be low, but their efficiency has improved in the recent years. Often these systems comprise solar cells arranged in an array, such as in a solar panel farm. The photovoltaic systems may or may not be combined with CSPs, or the CSPs may be standalone. CSPs work by using lenses, mirrors, and other optics devices to focus sunlight into a concentrated beam or light, using the heat of sunlight to generate electricity from conventional means, e.g. steam-driven turbines rather than converting photonic energy into electrical current. CSPs often employ dishes, parabolas, or other such shapes and orientations in order to properly focus the light beam. In one embodiment the CSP provides electrical energy to power the coal beneficiation plant.

[0066] The renewable energy source may comprise a hydroelectric source. Hydroelectric power currently represents approximately 70% of all non-nuclear renewable energy sources available, and just over 15% of total electricity worldwide. Accordingly, hydroelectric energy sources may represent an attractive renewable energy source. Hydroelectric sources may be traditional sources, such as dams, or they may be pumped-storage, tidal power stations, or run-of-the-river hydroelectric power stations. Like solar cells, hydroelectric power sources have a number of distinct advantages and disadvantages that one of ordinary skill in the art will appreciate when choosing which renewable energy source to integrate with a coal beneficiation process. Hydroelectric sources are flexible, have very low power costs, and are sustainable for industrial applications, e.g. the Hoover dam. Furthermore, they maintain a relatively constant power output level, as opposed to solar and wind. The power output of hydroelectric sources however, are not always robust, unless the scale of the dam is massive. Furthermore, hydroelectric power sources are relatively restrictive on where they can be located, unlike several other renewable energy sources, and must be located where water sources and terrain are suitable. Hydroelectric power sources may also have negative environmental impact, especially where damming is involved. Additionally, hydroelectric power output can vary seasonally.

[0067] The renewable energy source may comprise a wind power source. Wind power systems generally have a minor environmental impact, especially when compared to hydroelectric power sources, and have a smaller profile. Wind power sources are scalable, to a degree, in that wind farms can generally include the number of windmills needed to generate adequate power, but only up to a point; there is a point at which, like solar energy sources, that windmill farms become impracticable. This is typically accurate for large urban centers. However, wind power may represent a good candidate for a renewable power source to power coal beneficiation process because the power demands of coal beneficiation may be limited relative to larger scale energy needs, which may be satisfied through the coal product. Furthermore, the wind power sources are less restrictive in their placement than both solar power sources and especially hydroelectric power sources, making them an attractive option. Wind power sources, however, are intermittent in power generation like that of solar cells, although their power generation is not as temporally restricted as that of solar power, which is diurnal. Additionally, wind power sources typically generate less power than other renewable energy sources, but depending on the power needs of the coal beneficiation processes, may still represent an attractive option.

[0068] The renewable energy source may comprise wave power. Wave power is a relatively underutilized form of power, which harnesses the power of waves at sea and then captures the energy to perform useful work in a wave energy converter (WEC). Wave power is distinct from tidal power, in that wave power is a relatively constant source of energy owing to the steady gyre of ocean currents, whereas tidal power, like solar power, has a diurnal flux, owing to the tidal current. WEC technology may include point absorbers, attenuators, oscillating wave surge converters, oscillating water columns, overtopping devices, and submerged pressure differentials. The advantage of wave power is that it is a relatively constant source of renewable energy. The disadvantages of wave power is that it, like traditional hydroelectric power, is relatively fixed in location, and that like wind power, it is generally not capable of generating large amounts of electricity. However, as designs of WEC improve, these limitations may be overcome.

[0069] The renewable energy sources are integrated to the coal beneficiation processes so that the renewable energy source provides at least a portion of the energy to power the coal beneficiation process. The beneficiation process typically comprises reduction of the total water content of coal. Water is contained in coal in a number of different forms such as free water, bound water, and non-freezing water, which are all included in the total water content of the coal. In this invention, the reduction of coal moisture is not bound by which type of moisture is impacted, only that overall reduction of any water is reduced. The water content reduction can be less than about 1%, about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 11%, about 12%, about 13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 98%, about 99%, or greater than about 99%, and any intervening ranges therein. As defined herein, the water content reduction as measured by percent (%) water reduction is measured relative to the total water content of coal before and after beneficiation. By way of example, reducing water content from about 30% in pre-beneficiated coal to about 15% in beneficiated coal comprises a water content reduction of about 50%, and not of about 15%. The foregoing levels of water content reduction have been reported Claude C. Corkadel, GTL Energy, Australia in World Coal, November 2013 (https://www.worldcoal.com/magazine/world-coal/november-2013/), the entirety of which is hereby incorporated by reference.

[0070] The coal beneficiation process increases the stored energy content of the coal, typically corresponding to reduction of the total water content of the coal. The stored energy content is typically, although not necessarily, measured in BTUs. The stored energy content may be increased by about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 100%, about 110%, about 120%, about 130%, about 140%, about 150%, about 160%, about 170%, about 180%, about 190%, about 200%, or greater than about 200%, and any intervening ranges therein.

[0071] The coal beneficiation process may follow the following methods, although variations on such methods are within the knowledge of one of ordinary skill in the art and are expressly considered embodied by the present disclosure. Typically, the coal is crushed into macerals, optionally washed, compacted, dried, and then briquetted although the crushing and washing stage may occur in different order. The crushing can occur by a number of means known in the art, including, but not limited to, through mechanical force, shredding, tearing, or through sonication/vibrations. At this stage, the coal is typically (but not necessarily) low ranking coal, such as lignite coal. Before or, ideally, after being pulverized or crushed into macerals, the macerals are optionally subjected to a washing step, i.e. coal washing. Coal washing is a process known in the art by which the coal is separated based on difference in specific gravity and impurities such as shale or sand, such that the impurities are washed out and what is left behind is purer coal with a higher calorific value. The coal washing can occur via a jig or some other gravity separation method, such as a dense medium bath or a dense medium cyclone. A number of dense medium baths exist including but not limited to teska bath, daniels bath, leebar bath, drewboy bath, barvoys bath, chance cone, wemco drums, tromp shallow bath, and combinations thereof. After the optional washing, the macerals are typically compacted, although not necessarily.

[0072] The coal product is then subjected to water reduction, which serves to increase the total stored energy content of the coal as measured in the total energy content of the coal (e.g. in BTUs) per unit mass (e.g. gram or kilogram) of the coal. The water reduction may occur via a number of means, but particularly by mechanical water reduction, electrical water reduction, and thermal water reduction. Mechanical water reduction is perhaps the most common means of water reduction, and may occur by a number of processes. For example, the water reduction may occur by centrifugation, including but not limited to screen bowl centrifugation, slurry screening, de-watering cyclones, and/or horizontal belt filters, and combinations thereof. The mechanical water reduction could also occur via application of high pressure in order to drive the water out. The coal beneficiation process may also comprise electrical water reduction. The coal beneficiation process may comprise thermal water reduction. Typically, a source of external heat is applied to the coal in order to evaporate and drive the water off Thermal water reduction methods can be applied in conjunction with any of the other methods of water reduction. One preferred method of water reduction may utilize microwave-based demoisturization systems. Microwaves are capable of exciting the water molecules trapped in coal, thus allowing the water trapped within the coal to evaporate, without directly heating the coal.

[0073] The coal beneficiation process may occur at temperatures below a temperature at which coal and/or coal dust will spontaneously ignite, especially where microwave-based demoisturization systems are utilized. For example, the coal beneficiation process keeps the coal temperature below about 500 C., below about 475 C., below about 400 C., below about 375 C., below about 350 C., below about 325 C., below about 300 C., below about 275 C., below about 250 C., below about 225 C., below about 200 C., below about 225 C., below about 200 C., below about 175 C., below about 150 C., below about 125 C., below about 100 C., below about 95 C., below about 90 C., below about 85 C., below about 80 C., and any intervening ranges therein. Furthermore, in such embodiments, there is little to no oxidation or volatilization of the coal, thus leaving little to no harmful gasses or emissions from the beneficiation process, minimizing environmental impact.

[0074] The coal beneficiation process may include the addition of one or more coal additives to the coal during processing which would enhance the capture of mercury generated when the coal is burned. The coal additives may include one or more halogens, e.g. one or more of fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At), and combinations thereof, their ions, salts (e.g. a metal halide), or compositions containing one or more of fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At), and combinations thereof. The coal additives may include one or more metals or their ions, e.g. silver (Ag), copper (Cu), or nickel (Ni). The coal beneficiation process may comprise removal of high ash content from the coal product. The coal beneficiation process may comprise removal of mercury (Hg) and sulfur (S) containing compounds or compositions from the coal (e.g. SOx), as well as nitrous oxides (e.g. NOx) and related compositions.

[0075] As used herein and in the appended claims, the singular forms a, and and the include plural references unless the context clearly dictates otherwise.

[0076] Where a value of ranges is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges which may independently be included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either both of those included limits are also included in the invention.

[0077] The term about refers to a range of values which would not be considered by a person of ordinary skill in the art as substantially different from the baseline values. For example, the term about may refer to a value that is within 20%, 15%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value, as well as values intervening such stated values.

[0078] Publications disclosed herein are provided solely for their disclosure prior to the filing date of the present invention. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.

[0079] Each of the applications and patents cited in this text, as well as each document or reference, patent or non-patent literature, cited in each of the applications and patents (including during the prosecution of each issued patent; application cited documents), and each of the PCT and foreign applications or patents corresponding to and/or claiming priority from any of these applications and patents, and each of the documents cited or referenced in each of the application cited documents, are hereby expressly incorporated herein by reference in their entirety. More generally, documents or references are cited in this text, either in a Reference List before the claims; or in the text itself; and, each of these documents or references (herein-cited references), as well as each document or reference cited in each of the herein-cited references (including any manufacturer's specifications, instructions, etc.), is hereby expressly incorporated herein by reference.