WO2018144096A2

WO2018144096A2 - A biomass coal fuel and method of producing same

Info

Publication number: WO2018144096A2
Application number: PCT/US2017/060004
Authority: WO
Inventors: Dan QUERREY; Mark Atwood; Mannie Lee Clapp; Paul Andrew MALSCH; Timothy J. Bradley
Original assignee: Queston, Inc.
Priority date: 2016-11-04
Filing date: 2017-11-03
Publication date: 2018-08-09
Also published as: WO2018144096A3

Abstract

Disclosed is a method of producing biomass coal fuel. The method is directed to applying calcium carbonate to biomass forming a mixture, where the mixture is then compressed under elevated temperatures to form biomass fuel. The biomass fuel is added to coal to form a biomass coal fuel. The biomass fuel is formed from a mixture containing biomass and calcium carbonate results in the neutralization of organic acids found in the biomass and coal. Accordingly, upon combustion of the burning biomass coal fuel, a reduction in acidic by-products occurs.

Description

A BIOMASS COAL FUEL AND METHOD OF PRODUCING SAME

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This PCT application claims the benefit under 35 U.S.C. § 119(e) of U.S. provisional patent application number 62/417,885, entitled "Clean Burning Wood Biomass Fuel for Coal and Method of Producing Same" filed on November 4, 2016, the contents of the aforementioned application being hereby incorporated by reference in their entirety.

TECHNICAL FIELD

[0002] The present invention relates generally to a biomass fuel and a method of producing a biomass fuel for combustion with coal fuel, where the biomass fuel has advantages at combustion, that are an improvement over conventional coal fuel.

BACKGROUND

[0003] Typically, energy is generated by combustion of conventional natural resources, such as but not limited to coal, petroleum, and natural gas products. Due to diminishing quantities of these resources and their byproducts, there is a renewed interest in obtaining alternative renewable fuel sources of energy. With the growing importance of renewable energy, the use of wood fuel pellets has increased considerably based on their relatively and high energy content.

[0004] It is commonly known in the alternative fuel industry that wood pellets for fuel are generally a good source of energy due to their efficient burn and in particular, production of less ash, less smoke, and more heat compared to fossil fuel or conventional natural resources. (Hansen et al, English Handbook for Wood Pellet Combustion, Feb. 2009, National Energy Foundation, p. 1-86; http://worldwideweb.pelletsatlas.info). Wood pellets are surprisingly still advantageous over the use of wood chips even though wood chips as a source of fuel are cheaper. Wood chips contain a higher moisture content, generally around 25%; whereas, conventional wood pellets have a moisture content of less than 10% (RHPL Ltd.; BioEnergy Inc. "Advantages of Wood Pellets" http://worldwide web.bioenergyinc.ca WoodPellet Advantages/). The moisture content is directly related to the energy density which is the energy contained in a fuel per unit weight. Fossil fuels have the highest energy density which is up to about three times that of either wood pellets or wood chips. Wood pellets must have an energy density of 16.8 GJ/ton as required by the British BioGen code of good practice (Ibid). Whereas, wood chips may vary depending on their moisture content. For example, at a moisture content ranging from 25% to 50%, the energy density of wood chips ranges from 14.3 GJ/ton to 9.5 GJ/ton (Ibid). Thus, wood pellets are becoming the preferred choice of biofuel since fossil fuels and high- quality trees are diminishing resources. Moreover, wood pellets as a source of fuel, typically require less energy to produce and transport. The quality of the biomass used to form wood pellets plays a role, since a less desirable biomass starting material may include binders, starches, oxidizing agents, chemicals, and the like, which upon burning, results in undesirable byproducts that adversely affect the environment.

[0005] It is the common understanding that wood pellet production often requires addition of a binding agent because the binding properties of the lignins naturally found in the biomass are insufficient for maintaining the shape and structure of wood pellets. U.S. Patent No. 4,236,897, WO 2009/139621, and WO 2009/044375 all utilize additional materials to form wood pellets, including, for example, thermoplastic materials, flours, oxidizing compounds, zeolites, adsorbents, starches, and the like. The methods of producing a wood pellet as disclosed in these publications discuss the difficulties of achieving a wood pellet without binding agents. They also disclose a moisture content of the wood that is relatively low or dry.

[0006] Some of inferior conventional pellets may be composed of impure wood products and corners may be cut during the manufacturing process by utilizing wood products that have a higher moisture content. Using a lower drying temperature requires less energy, and hence less cost is required to dry the wood products having a higher moisture content. Since conventional pellet mills operate at a temperature ranging from 212 °F to 350 °F anyway, where water evaporates at 212 °F, companies may forgo the extra energy needed to dry the wood products to the desired dryness. Another reason that conventional pellet mills operate at this temperature range is to obtain some natural binding properties since lignins found in wood melt at less than 392 °F (Beis, et al. (2010) "Fast Pyrolysis of Lignins," BioResources 5(3): 1408-1424).

[0007] Unfortunately, the byproducts created when burning conventional wood pellets as a fuel source that contain additional components, binders, impurities, and the like are undesirable. Conventional wood pellet byproducts include solids such as ash and vapors that include various forms of acid, dioxides, and other chemicals that are harmful to the environment. Moreover, the smoke produced by burning conventional wood fuel pellets that contain numerous harmful chemicals and additives is also detrimental to the environment.

[0008] Additionally, wood pellets do not have the energy density of other fossil fuels like coal and as a result power plants continue to use coal as a primary fuel source. The harder forms of coal are composed primarily of carbon, along with quantities of other elements like hydrogen, sulfur, oxygen and nitrogen. Some of the most common types of coal burned at coal- fired power plants are anthracite coal, bituminous coal and lignite coal. Anthracite coal is the oldest and hardest of the coal types, and contains a high percent of carbon above 85%, and has a high energy content of around 23 million Btu per ton. Bituminous coal contains 45% to 85% carbon, and a high energy content of around 18 million Btu per ton. Lignite coal is the youngest softest coal type when compared to bituminous coal and anthracite coal, and consists of 25% to 35% carbon, and contains only 13 million Btu per ton. Additionally, coal can contain up to ten percent sulfur depending on the region the coal was mined. The mores sulfur content the more sulfurous gas or sulfur dioxide is produced by the combustion of coal. Coal-fired power plants are the largest human-caused source of sulfur dioxide and are the main contributors to acid rain. Byproducts created when burning coal as a fuel source include flying ash, carbon dioxide, sulfur dioxide, nitrogen oxide, and mercury (Coil et al., Coal Combustion Wastes, October, 2014 http://www.groundtruthtrelcking.org/Issues/AlaskaCoal/Coal-Ash-Combustion-Wastes.html). Additional byproducts can also include carbon monoxide, dinitrogen monoxide, hydrogen chloride and fluorine.

[0009] Therefore, there is a need for a coal biomass fuel that drastically reduces, the objectionable byproducts like sulfur dioxide that typically result from burning conventional coal alone. Moreover, in addition to reducing the environmental byproducts, an efficient method of manufacture that utilizes fewer inputs, fewer parts or components in the assembly line, expedites the rate of production, and thereby, reduces the time from production to user are also desirable.

SUMMARY

[0010] The deficiencies of the prior art, namely the production of the undesirable byproducts, are substantially overcome in consideration of the invention disclosed herein. More specifically, additional innovation and advantages are realized when configuring the inventive biomass fuel to obtain a desired result during the production stages and a desired result during the burning of the biomass fuel with coal.

[0011] One object of the invention relates to a method of producing a biomass fuel, where the method comprises applying calcium carbonate to a biomass to form a mixture, and forming a biomass fuel from the mixture, and mixing the biomass fuel with coal to form a biomass coal fuel.

[0012] These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG.l illustrates a flow diagram of mixing a biomass fuel with coal to form biomass coal fuel according to an exemplary embodiment of the present invention.

[0014] FIG. 2 shows the graphical depiction of the reduced pollutants in comparison of combusting coal without the biomass fuel and with the biomass fuel.

DETAILED DESCRIPTION

[0015] The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

[0016] Various inventive features are described below that can each be used independently of one another or in combination with other features.

[0017] Numerical ranges as used herein are intended to include every number and subset of numbers contained within that range, whether specifically disclosed or not. Further, these numerical ranges should be construed as providing support for a claim directed to any number or subset of numbers in that range.

[0018] Broadly, embodiments of the present invention generally provide biomass coal fuel containing calcium carbonate (CaC0₃) and a method of producing this biomass coal fuel. These biomass coal fuels bum cleaner, have fewer, impurities that would adversely affect a clean burn, and may utilize typically inferior biomass and coal to produce the beneficial results. [0019] In the present invention, a method of incorporating calcium carbonate into a biomass coal fuel is disclosed where the method enables the production of a biomass coal fuel, which when burned produces less ash and the vapors contain lower levels of pollutants. Furthermore, the method of incorporating calcium carbonate into a biomass coal fuel directly relates to the desired results of reducing the level of acid and environmental contaminants, such as, for example, greenhouse gases, methane gas, nitrogen oxides, and carbon monoxide. This is more specifically realized when the method of producing a biomass coal fuel comprises mixing a biomass, and calcium carbonate, and coal.

[0020] In the method of producing a biomass coal fuel in the present invention where the desired result is to include the substance, calcium carbonate, such that the desired result equals less acid in the vapor when burned alongside coal, the method of production must include the addition of the calcium carbonate prior to the formation of the biomass fuel such that calcium carbonate remains active when mixing the biomass fuel with coal. In one embodiment, the method of producing a coal biomass fuel is directed to steps that mix a biomass or a supply of biomass and a calcium carbonate or a supply of calcium carbonate and coal, where the calcium carbonate, as defined here, may be pure calcium carbonate, substantially pure, or the calcium carbonate may be a part by volume of another substance containing inert material. Non-limiting examples of inert materials that may be found in calcium carbonate tailings, for example, include vegetable oil, animal fat, which may include, for example, chlorite, plagioclase, feldspar, quartz, mica, barium, toluene, petroleum products, tall oil, ortho-phenyl phenol, acetone, isopropyl alcohol, stearic acid, polyacrylamide, acrylamide monomer, polyacrylates, phosphorus, methyl isothiocyanate, ethylamine, and free chlorine.

[0021] The calcium carbonate useful for the inventive method may have a particle size ranging from about 0.1 microns to about 100 microns. In a preferred embodiment, the particle size ranges from about 0.1 microns to about 50 microns, and more preferably, the calcium carbonate particle size is about 0.2 microns. These lower ranges of particle size may allow the CaC0₃ to better mix with or coat the biomass. In addition, this range of particle size may also assist to expedite the chemical reaction between the CaC0₃ and the acids found in the biomass.

[0022] Another embodiment is directed to a particle size that is sufficient to completely cover the biomass. The calcium carbonate particle size must be sufficiently sized to cover at least about 80% of the biomass. In preferred embodiments, the calcium carbonate covers at least about 85%, about 90%, or about 95% of the biomass, and most preferably, the calcium carbonate covers about 100% of the biomass.

[0023] The amount of calcium carbonate added to the biomass may represent between about 15.0 weight% to about 25.0 weight% of the biomass during production of the biomass fuel. The addition of CaC0₃ to the biomass in the amount of about 15.0 weight% to about 25.0 weight% may greatly reduce or eliminate many of the pollutants typically found in conventional wood pellets whereby about 4.0 weight% of CaCo3 chemically reacts with the CaC0₃ in the inventive biomass fuel with chemicals found in the biomass having a pH of less than about 7 (i.e., for example, organic acids), thereby resulting in the production of a calcium salt, water, and carbon dioxide and leaving about 11 weight% to 21 weight% of CaC03 remaining in the biomass fuel such that it may greatly reduce many of the pollutants typically found in the exhaust from burning coal.

[0024] The calcium carbonate may be applied to the biomass by sprinkling a consistent layer onto the biomass, with or without shaking, in order to distribute the calcium carbonate evenly on the surface of the biomass. Alternatively, or additionally, the biomass and calcium carbonate may be mixed in a mixer, tumbler, drum blenders, double cone blenders, screw blenders, or the like, where mixing the biomass and calcium carbonate results in sufficiently covering the biomass with at least about 80% to about 100% calcium carbonate, or preferably about 90% to about 100% calcium carbonate, where some calcium carbonate may be of a particle size that enables the calcium carbonate to fit in the pores of the biomass. The biomass starting material for producing the biomass fuel described here may be from hardwood, softwood, recycled wood, wood parts, including but not limited to wood chips, shavings, sawdust, bark, branches, and the like. Non-limiting examples of softwoods include conifers, pine, cedar, fir hemlock, redwood, cherry, elm, and spruce, while hardwoods are from deciduous trees, such as but not limited to, hickory, oak, ash, cherry, maple, beech, birch, walnut, and poplar. Other types of wood may also be useful, including but not limited to, mahogany, rosewood, teak, and wenge. The described method advantageously makes use of a variety of wood types which may be less pure, as compared to conventional wood pellets which prefer using a high-quality wood that does not contain bark, paper, cardboard products, or other impurities.

[0025] Both hardwoods and softwoods primarily contain three components: cellulose at about 40% to 50% by weight, hemicelluloses at about 20% to 30% by weight and lignin at about 20% to 30% by weight. Studies have shown that hardwoods and softwoods produce different levels of pollutants, ash, and heat. This requires the addition of different levels of CaC0₃ during the manufacturing process to achieve the desired reduction of pollutants in the emissions and the ash.

[0026] The biomass may be composed of various sized parts of wood or tree materials generally no larger than the size of the desired biomass fuel final product. As it is understood by one of skill in the art, the biomass fuel may be formed into any shape or size. A preferred shape of the biomass fuel is that of a pellet which may be particularly useful for burning in wood pellet stoves. Although the biomass fuel may preferably be in the shape of a pellet as formed by a pellet mill, any shape is contemplated using compression equipment that shapes the biomass fuel into the desired shape. The biomass fuel may alternatively be in the shape of a disc, briquette, cube, and the like. However, one advantage of a biomass fuel in the shape of a pellet is the ease of transport and storage. The pellet having a uniform size and shape allows for a large capacity to be easily transported and stored.

[0027] Since the preferred shape of the biomass fuel is that of a pellet, the exemplary operating system uses a pellet mill to form the biomass fuel. Although any size of the biomass may be used, the preferred predetermined biomass size may be about one quarter of an inch (¼ - inch) in diameter, or of a size such that the biomass may pass through a quarter-inch die that is part of a pellet mill. In another embodiment, the predetermined biomass size would have a diameter that is sufficient for fitting in an appropriately sized pellet mill die.

[0028] Although the art teaches away from using wood chips as a fuel because of its high moisture content and low energy density, the inventive biomass fuel preferably has a moisture content similar to that found in wood chips, which is higher than conventional wood pellets. The moisture content of the biomass starting material prior to formation of the biomass fuel may range from about 10 % to about 25 % and preferably from about 13 % to about 15%. This is in contrast to the moisture content of conventional wood pellets which preferably have a lower moisture content to result in a more efficient wood pellet since less energy is necessary to form and bum the wood pellet as compared to high moisture containing wood chips. (Nielsen, et al. "Analysis Methods for Pelletizing Properties of Wood," Wood and Fiber Science, 41(4), 2009, pp. 414^25). Hansen et al. at report that the water content in the raw material must be about 10 % before the pellet process begins and that a water content, or moisture content, of higher than 15 % makes the raw material difficult to form pellets {English Handbook for Wood Pellet Combustion, Feb. 2009, pp.1-86).

[0029] Although any pellet mill may be utilized, a preferred pellet mill may withstand and operate at an elevated temperature greater than about 550°F. In a preferred embodiment, the elevated temperature or operating temperature ranges from about 550°F to about 650°F. This elevated temperature range is about 1.5 to about 3 times that of the temperature range at which pellet mills typically operate for producing conventional wood pellets. Conventional wood pellets may be formed under a temperature ranging from 212°F to 350°F because water evaporates at 212°F and a drier wood pellet assists with combustion. Nielsen, et al. reported unpublished data that the heat generated by the pelletizing process maintained the operating die temperature at 110°C to 130°C {i.e., 230°F to 266°F) (Nielsen, et al. "Analysis Methods for Pelletizing Properties of Wood," Wood and Fiber Science, 41(4), 2009, pp. 414^125). Since lignins from wood may act as a natural binder, methods of manufacturing conventional wood pellets typically take advantage of that property and operate at a temperature around 300 °F which is the temperature at which lignins melts. Moreover, methods of producing conventional wood pellets strive to be efficient and using such elevated temperatures would typically be thought to be excessive for producing a conventional wood pellet. This elevated temperature would not be desirable for forming a conventional wood pellet because the energy required to produce the pellet would be more than the benefits achieved upon combustion. In fact, one of skill in the art would believe that the inventive method is very inefficient since so much energy would be wasted to form the biomass fuel. Moreover, conventional methods avoid such elevated temperatures since wood ignites at 572°F. Despite the problems and perceived inefficiencies that arise from operating at a temperature greater than about 550°F, the inventive biomass fuel may be produced at a temperature ranging from about 550°F to about 650°F, more preferably from about 565°F to about 575°F, while the most preferred temperature may be one that mostly reacts the calcium carbonate and the organic compounds (for example, organic acids) found in biomass. The higher moisture content of the biomass is necessary for the method of producing the inventive biomass fuels in order to avoid ignition of the wood during the production stage and is one of the parameters for controlling the operation to avoid ignition.

[0030] In view of the elevated temperature necessary to achieve the desired biomass fuel, the biomass cannot remain in the pellet mill for an extended period of time. More specifically, the wood cannot be in contact with the die during compression to form the biomass fuel longer than necessary since wood naturally ignites at a temperature of 572°F. Another parameter that may be utilized for controlling the operation of forming the desired biomass fuel is the length of time that the biomass is under compression or, for example, in the die of the pellet mill when forming biomass fuel pellets. The preferred length of time ranges from about 0.25 seconds to about 1 second, and more preferably, about 0.5 seconds. If the biomass remains in the die or in contact with equipment that operates at the elevated temperatures above the wood ignition temperature, more moisture in the biomass may evaporate resulting in a drier biomass that can more easily ignite. Therefore, in addition to moisture content, time is another parameter used to control the method of producing the desired biomass fuel.

[0031] The elevated temperature was found to be one means for reacting calcium carbonate and the organic compounds naturally found in biomass. Typically, when wood is burned as fuel, the exhaust or resulting gases contain these undesirable and hazardous organic compounds or acids. Essentially, the acids in the wood remain and are subsequently burned resulting in acidic gases. Therefore, in order to reduce the volatile organic compounds (VOCs) that are naturally found in wood and that remain in the exhaust gases upon combustion of the wood, a means for removing the VOCs from the wood or the exhaust gases is highly desirable. The inventive method described here achieves neutralization of the VOCs. Major organic acids found in wood include, but are not limited to, formic acid, acetic acid, propanoic acid, butanoic acid, phenolic acid, and benzoic acid. Reacting these and any other detrimental acids found in wood with calcium carbonate essentially results in the production of water, carbon dioxide, and a calcium salt, all of which are more desirable as they are not toxic or hazardous to the environment; however, some residual calcium carbonate may be present. Acids in the exhaust gas that occurs typically when conventional wood pellets are burned are not desirable and in fact toxic to the environment.

[0032] Briefly, the method of producing a biomass fuel as described here involves, in one embodiment of the invention, applying, distributing, coating, or sprinkling, all of which may be used interchangeably here, calcium carbonate onto the outer surface of the biomass in a uniform, consistent, and even fashion. The application of the calcium carbonate at this stage is not critical and other methods may be used such that the calcium carbonate evenly covers about 80 % to about 100 %, more preferably about 90 % to about 100 %, of the surface of the biomass, preferably in a uniform, consistent manner. Non-limiting examples of methods for applying the calcium carbonate onto the biomass may include distributing the calcium carbonate by releasing the calcium carbonate, spraying the calcium carbonate, mixing the calcium carbonate, coating with calcium carbonate, applying the calcium carbonate, and the like onto the biomass. In another embodiment, the biomass and the calcium carbonate may be mixed through a type of tumbling or mixing process to ensure adequate coverage either subsequently to the application of the calcium carbonate to the biomass or in lieu of the application. Mixing the calcium carbonate and the biomass essentially results in the calcium carbonate coating the biomass. Another embodiment is directed to the amount by weight of the biomass and calcium carbonate. The preferred amount of calcium carbonate to biomass ranges between about 15.0 weight percent to about 25 weight percent and more preferably from about Γ9.0 weight percent to about 21.0 weight percent where about 4.0 weight percent of the calcium carbonate reacts with the biomass leaving about 15.0 weight percent to 17.0 weight percent remaining within the biomass fuel to react with the coal. Upon completion of mixing the biomass and the calcium carbonate, a biomass mixture or mixture results.

[0033] The next step is to introduce the biomass mixture into, for example, a pellet mill, which has the ability to compress the biomass mixture by means of pressure into a biomass fuel of the desired size and shape. This high pressure causes heat to form whereby the high pressure and heat causes the calcium carbonate to react with the various forms of acid in the biomass such that a chemical reaction occurs. As previously described, the chemical reaction that the inventive method of producing a biomass fuel achieves neutralizes the acid naturally found in the biomass, thereby producing the desired biomass fuel. This enables a significant reduction in the VOC or acid levels in the smoke when the biomass fuels are burned. Such VOCs or acid is undesirable for the environment. An example of an acid is acetic acid, and other examples include but are not limited to formic acid, propanoic acid, butanoic acid, phenolic acid, and benzoic acid. One embodiment of the chemical reaction that occurs to neutralize the various forms of acid is further illustrated in TABLE 1 below. TABLE 1

[0034] To enable the chemical reaction between the calcium carbonate and the acidic properties, other parameters have to be considered to yield the preferred desired outcome during the production of the advanced biomass fuel. Such parameters include the amount of other materials and impurities in the biomass, the amount of water in the biomass, the temperature of the operation, the time the biomass is exposed to the temperatures, etc.

[0035] The step during which the equipment forms the desired biomass fuel, for example, a pellet mill, by applying high pressure and heat must be considered in the method of producing a biomass fuel as described here since the high pressure and temperature may cause the wood to self-ignite. Additionally, if there is too much water, or too high of a moisture content, the pellet mill will not generate enough heat to bind the biomass into a shape that does not fall apart, nor will the desired chemical reaction occur. Therefore, it is important in that in this step the amount of moisture within the biomass fuel be in the range from about 10% to about 25%, preferably about 13%) to about 15 >. Another parameter that is important during the step of applying high pressure and heat to a biomass such that it does not ignite when the biomass fuel is formed is the level of heat as the pellet mill applies high pressure. The temperature cannot be too low such that the biomass fuel loses its shape and structure and the desired chemical reaction or neutralization of acid cannot occur, and the heat cannot be too high such that the biomass fuel ignites during or soon after exiting the pellet mill or die of the pellet mill. A preferred temperature range is between about 550°F and about 650°F degrees Fahrenheit. Additionally, the time during which the biomass fuel is compressed in the die is preferably for an amount of time ranging from about 0.25 seconds to about 1 second. However, if the time is extended then the temperature range would need to decrease otherwise the biomass would more likely ignite since the moisture in the biomass evaporates, thereby drying the biomass making it more susceptible to self-igniting. [0036] In one embodiment of the invention, a biomass fuel formed of a pellet that is approximately one-half inch (½ inch) long and one quarter inch (¼ inch] in diameter with coal. More specifically, the biomass fuel consists of a high content of unreacted calcium carbonate about 15 percent by weight to about 17 percent by weight as it is mixed with coal.

[0037] As represented in Fig. 1, the biomass fuel in the form of a pellet 10 is fed into a pellet pulverizer 11 which consists of a heavy roller meant to crush the pellet into biomass particles 12 ranging from 100 microns to 200 microns and a mean particle diameter between 130 microns and 160 microns such that they are easily transportable by forced air. The biomass particles 12 become airborne and are carried away from the pellet pulverizer 11 by pipe 13 utilizing forced air. Similarly, coal 15 is placed in a coal crusher 16 arid crushed into coal powder 17 with a particle size ranging from 100 microns to 200 microns and a mean particle diameter between 130 microns and 160 microns such that they are easily transportable by forced air. The coal powder 17 become airborne and is carried away from the coal crusher 16 by pipe 18.

[0038] Briefly, the method of producing a biomass coal fuel as described here involves, in one embodiment of the invention, pulverizing the biomass particles 12 and pulverizing the coal powder 17 to a size of 100 microns to 200 microns and a mean particle diameter between 130 microns and 160 microns. The size of the biomass fuel 12 and the coal powder 17 is directly related to the transportation method. A particularly important part of the invention is later realized when the particle size of the biomass particles 12 and the particle size of coal powder 17 are substantially equal.

[0039] The biomass particles 12 and the coal powder 17 are then mixed together by forced air in a mixing tube 23 to form a biomass coal fuel 30. The ratio of pellet particles 12 to coal powder 17 to form the biomass coal fuel 30 is about a one-to-one ratio but can vary by ten percent either way. The ratio of biomass particles 12 to coal powder 17 is controlled through a baffle system that consists of a pellet baffle 20 and a coal baffle 21 and a sensor, not shown. The biomass coal fuel 30 is continually mixed by forced air as it travels towards the burners 35. Introduction of a fan blade or other common air mixing devices can be added to the mixing tube 23 for a more efficient mixing process. The burners 35 transport the biomass coal fuel 30 into the boiler 40 where the biomass coal fuel 30 is ignited by hot air 45 at approximately 500 degrees Fahrenheit, produced by a heater 46 that is attached to the boiler 40. The boiler 40 is designed to withstand internal temperatures of 4500 degrees Fahrenheit and provide an environment of which external oxygen and other air particulates are controlled.

[0040] The biomass coal fuel is smartly designed to ignite and combust in phases. In the first phase, the wood in the biomass particle 12 ignites when introduced to the hot air 45 and begins combustion resulting in the release of moisture among other byproducts. The combustion of the wood in the biomass particle 12 grows as the volatile matter flows through the porous biomass particle and causes the heat within the boiler 40 to increase. The increased heat triggers the second phase of the combustion process.

[0041] The second phase of the combustion process occurs when the coal of the biomass coal fuel 30 reaches a temperature of approximately 650 degrees Fahrenheit. The density and less porous nature of coal does not allow the volatiles to flow out of the coal powder 17 thereby resulting in a swelling of volatiles within the coal as it is exposed to additional heat until the surface of the coal is breached, and the coal surface ignites with jetting volatiles. As a result of coal's combustion process the temperature in the boiler rises significantly. The length of time combustion occurs in coal is significantly longer, more than double in comparison with biomass of a similar size. Furthermore, the combustion of the coal results in the byproduct of carbon monoxide, carbon dioxide, nitric oxide, nitrite, dinitrogen monoxide, sulfur dioxide, hydrogen chloride and fluorine. Coal combustion significantly raises the temperature in the boiler, thereby triggering the third phase of the combustion process.

[0042] The third phase of the combustion process occurs when the remaining calcium carbonate approximately 11 weight% to 21 weight% of the biomass, undergoes thermal decomposition which begins at approximately 875 degrees Fahrenheit. The thermal decomposition of calcium carbonate releases calcium oxide and carbon dioxide within the boiler 40. The timing of this third phase of the combustion process enables the calcium oxide to interact and neutralize the acidic by-products that resulted from the combustion of coal. The neutralization of acidic by-products, is further illustrated in TABLE 2 below: TABLE 2

[0043] As represented in Fig. 2 which contains the results taken from an independent lab burning the biomass coal fuel several harmful byproducts where significantly reduced. The top portion of each cell reflects the level byproducts resulting from the burning of coal, while the bottom portion of the cell reflects the level of byproducts resulting from the burning of the biomass coal fuel.

[0044] Turning back to Fig. 1 , upon completion of the combustion process the gas and heat from the combustion rises to a radiator 53 or to a series of pipes carrying water 51 supplied by an external water tank 50 thereby heating and converting the water 51 into steam. The steam is then used to power a steam generator 55 which generates electricity.

[0045] It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.

[0046] Features of the various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety. Aspects of the disclosure can be modified, if necessary, with various configurations, and concepts of the various patents, applications, and publications to provide yet further embodiments of the disclosure.

[0047] These and other changes can be made to the disclosure in light of the above- detailed description. In general, in the following claims, the terms used should not be construed to limit the disclosure to the specific embodiments disclosed in the specification and the claims, but should be construed to include all systems and methods that operate in accordance with the claims. Accordingly, the invention is not limited by the disclosure, but instead its scope is to be determined broadly by the following claims.

Claims

What is claimed is:

1. A method of producing a biomass coal fuel, comprising:

applying calcium carbonate to biomass to form a mixture;

forming a biomass fuel from the mixture at a temperature ranging from about

550°F to about 650°F;

mixing the biomass fuel with coal to form a biomass coal fuel.

2. The method of claim 1, wherein the calcium carbonate is in an amount ranging from about 15 weight% to about 25 weight% of the biomass.

3. The method of claim 1, wherein the biomass fuel comprises calcium carbonate, is in an amount ranging from about 11 weight% to about 21 weight% of the biomass.

4. A method of producing a biomass coal fuel, consisting of:

applying calcium carbonate to biomass to form a mixture;

forming a biomass fuel from the mixture; and

mixing the biomass fuel with coal to form a biomass coal fuel.

5. The method of claim 4, wherein the biomass fuel forms at a temperature ranging from about 550°F to about 650°F.

6. The method of claim 4, wherein the calcium carbonate is in an amount ranging from about 15 weight% to about 25 weight% of the biomass.

7. The method of claim 1, wherein the biomass fuel comprises calcium carbonate is in an amount ranging from about 11 weight% to about 21 weight% of the biomass.

8. A method of producing a biomass coal fuel, comprising:

forming a mixture, wherein the mixture consists of calcium carbonate and biomass;

forming a biomass fuel from the mixture;

pulverizing the biomass fuel;

pulverizing coal; and

mixing the pulverized biomass fuel with pulverized coal to form biomass coal fuel.

9. A biomass coal fuel, substantially consisting of:

biomass; calcium carbonate; and

coal, wherein the calcium carbonate reacts with the biomass and the coal to reduce acidic byproducts.

10. A biomass coal fuel of claim 9, wherein the calcium carbonate is about 11 percent by weight to about 21 percent by weight of the biomass.

11. A biomass coal fuel of claim 9, wherein the biomass and the coal each have a particle size of of 100 microns to 200 microns.

12. A biomass coal fuel of claim 12, wherein the biomass and the coal each have a mean particle diameter between 130 microns and 160 microns.

13. A biomass coal fuel of claim 12, wherein the biomass and the coal each have a substantially equal particle size.

14. A biomass coal fuel of claim 9, wherein the biomass to coal ratio is within 10 percent of a one-to-one ratio.

15. A biomass coal fuel of claim 9, wherein each the biomass, coal and calcium carbonate have a different combustion temperatures.

16. A biomass coal fuel of claim 15, wherein the biomass has the lowest combustion temperature.

17. A biomass coal fuel of claim 15, wherein the coal has a combustion temperature of about 650 degrees Fahrenheit.

18. A biomass coal fuel of claim 15, wherein the calcium carbonate has a combustion temperature of about 875 degrees Fahrenheit.

19. A biomass coal fuel of claim 9, wherein upon combustion coal creates at least one acidic by-product comprising acetic acid, propanoic acid, butanoic acid, phenolic acid, benzoic acid, carbon monoxide, carbon dioxide, nitric oxide, nitrite, dinitrogen monoxide, sulfur dioxide, hydrogen chloride, hydrogen fluoride, and fluorine.

20. A biomass coal fuel of claim 9, wherein the biomass, coal, and calcium carbonate ignite and combust in three phases.