Patent Application
20160102264
The invention relates to making fuel compositions from cellulosic by-product combined with coal fines, pelletized into a solid form, fuel compositions, and a pelletized product.
The Energy Independence and Security Act of 2007 requires the United States to make one billion gallons of cellulosic ethanol from wheat straw, corn stover, rice straw, soybean stubble, milo stubble, forage sorghum, prairie hay, woodchips, cotton-gin residue, and a dozen other forms of agricultural waste. To accomplish this cellulosic producers convert hemicellulose and cellulose also known as c5 and c6 sugars to a liquid fuel or chemical. The biomass plant structure is also composed of lignin and is the skeleton of the biomass; this fraction of the plant structure is not processed and becomes a by-product to a facility in the form of liquid cellulosic syrup and cake. Meaningful volumes of cellulosic by-product and cake, material have not been brought to market on a commercial scale due extensive cost of processing and drying and difficulties in integrating the supply chain to source, transport, storage, and processing of the material at a profit. As the Liquid fuel industry grows there will be a need to produce a viable marketable combustion source fuel with the by-product. The BTU for this byproduct ranges from 3000 BTU to 5500 BTU to produce a higher heat value product that the coal burning boilers and biomass boilers need. Coal fines can be utilized to increase the BTU value and help mitigate the environmental impact coal fines have in the mining industry. In coal mining processing and handling of traditional coal an enormous tonnages of coal fines are created, with the mining activities of the past coal washing did not have the advancement of today's washers and as a result large composites of these fines exist in decommission mining sites as well as active sites and create an environmental hazard as a result of storm water creating run off to our nations waterways. Typically, after handling and cleaning is completed, about fifteen to twenty percent of the tonnage mined consists of fines ranging in size from powder to small granules For the most part, these fines are not directly usable, and thereby leaving great quantities of material that is wasted and represents a hazardous and expensive disposal problem. Accordingly, coal-fines handling, storage and disposal operations represent a significant and unproductive expense for the industry.
With the passing of coal fines from coal mining processing is a powdery byproduct that has potential value as fuel, but is difficult to handle and transport due to the lightweight nature of the fines. Cellulosic ethanol production utilizes lignocellulosic biomass which produces a cellulosic by-product, which can also be burned, as disclosed in published patent application U.S. 2012/0102823.
A need still exists for a solid fuel composition which is easy to handle and transport, and utilizes materials which otherwise have relatively low value as byproducts from other processes.
This disclosure describes a pelletized fuel product made from coal fines mixed with a cellulosic by-product. The coal fines range from about 50% to about 90% by weight and the cellulosic by-product ranges from about 10% to about 50% by weight. The pelletized fuel product includes a mixture of the coal fines and the lignocelluosic by-product and pellets formed from the mixture.
This disclosure also describes a process for making a fuel composition. The process includes mixing a cellulosic by-product with coal fines to produce a mixture, and solidifying the mixture into a fuel composition. This disclosure further describes a fuel composition including a cellulosic by-product and coal fines.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Other aspects and advantages of the claimed subject matter will be apparent from the following Detailed Description of the embodiments and the accompanying figures.
The Detailed Description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items. The figures do not limit the claimed subject matter to specific embodiments described herein.
A primary objective of the present disclosure is a fuel composition containing cellulosic by-product from ethanol processing and coal fines from coal processing. Cellulosic by-product may be successfully converted into renewable fuels by combining with coal fines.
A further objective of the present disclosure is a pelletized fuel product containing cellulosic by-product and coal fines.
A further objective of the present disclosure is a process for pelletizing coal fines and cellulosic by-product to form a solid fuel composition.
Another objective of the present disclosure is fuel pellets made from coal fines and the cellulosic by-product of ethanol production.
A further objective of the present disclosure is a pelletized fuel product which is economical to manufacture and easy to handle and transport.
These and other objectives will become apparent from the following description of the invention.
The end product of the process is a solidified fuel composition including coal fines and cellulosic by-products, such as syrup from ethanol production. The solidification is preferably accomplished by pelletization so that the fuel composition is in a pellet form, though other means of solidification are within the scope of the invention, such as drying, heating, compression, densification, and the like, as well as other solid forms.
The U.S. published patent application number 2012/0102823 describes a lignocellulosic syrup production process. The syrup contains 40-70% solids, about 10-30 g/L of acetamide, about 40 g/L of sugars, at a density of about 1-2 g/cm3, and a viscosity less than 100 centipoise at 60° C.
The cellulosic by-product 104 may range from about 10% to about 50% by weight of the mixture. The cellulosic feedstocks used to generate the cellulosic by-product 104 may include, but are not limited to, corn stovers: leaves, husks, stalks, cobs, grain sorghum, energy sorghum, switchgrass, captive fiber, biomass, energy crops, wood crops, plants, trees, bushes, grasses, corn grain, and the like. As discussed, the cellulosic by-products 104 are produced as a by-product from the fermentation process of cellulosic ethanol production. A biochemical process utilizes several pretreatment and hydrolysis steps to rupture the lignin walls surrounding cellulose and hemicellulose fibers. This makes these fibers available for fermentation to ethanol. However, this process leaves about 15 percent to 30 percent of the input biomass mass as unconverted lignin. Cellulosic by-products 104 may be a cake, which is more like a powdered substance, or syrup, which is a wet liquid product. The coal fines and syrup both have value as fuel.
Embodiments include a mixture, which may range from about 50% to about 90% coal fines 102 and about 10% to about 50% cellulosic by-product 104 by weight. In one embodiment, the coal fines 102 may range from about 60% to about 80% by weight of the mixture and the cellulosic by-product 104 may range from about 20% to about 40% by weight of the mixture. In another embodiment, the coal fines 102 may range from about 50% to about 70% by weight and the cellulosic by-product 104 may range from about 30% to about 50% by weight of the mixture.
The final moisture content of the pelletized fuel pellet 112 or fuel composition is preferably 10-40%, and preferably less than 30%. In another embodiment, the moisture content of the pelletized fuel pellet 112 or fuel composition may be less than 35%.
In yet another embodiment, the cellulosic by-product 104 may be syrup, which may act as a binder for the powdery coal fines. That is, the syrup will bind the powdery coal fines together.
The processes of
The syrup and coal fine mixture may be treated using heat, compression, extrusion, pelleting, molding, and/or drying.
The final shape of the fuel product may be in the form of pellets, or other shapes. For example, the mixture may be extruded through a dye at an elevated temperature and/or elevated pressure, then pelletized, and then dried to form hardened fuel pellets. The pelletizer reduces volume and increases density of the fuel composition, which simplifies handling and transportation.
The solid fuel product can be burned for many applications, such as fuel pellets for use in a pellet stove or furnaces, industrial boiler, and the electrical generation industry, as well and co-gen application.
The cellulosic by-product 104 is preferably received and stored in a vessel 106 that may be equipped with a metering pump for measuring syrup discharge from the vessel 106. The coal fines 102 may be received and stored in a tank (not shown) equipped with a metering conveyor. The cellulosic by-products 104 and the coal fines 102 may be conveyed to a mixer which combines and mixes these ingredients into a viscous mixture. Preferably, the metering systems will provide a continuous flow of the cellulosic by-product 104 and the coal fines 102 to the mixer. The mixer may be incorporated in the vessel 106 or may be separate from the vessel 106.
Then, the mixture is then pumped from the mixer by a pump, or otherwise transported to one or more pellet mills 108, which use heat and pressure to form pelletized fuel products. The pellets are discharged onto a conveyor, which delivers the hot pellets to a cooling station. The final, cool and densified pellets are conveyed by one or more conveyors to a storage site or to trucks for transport.
In an embodiment, the component streams are effectively mixed, the mixture is transferred into a secondary retention style mixer where it has time to intimately mix into a consistent mixture including the additive prior to or after shearing. Each shearing device may be equipped with a metering conveyor to allow for optimum throughput and performance, which is indicated through pressure and temperature monitoring of the product. Proper conditions within the shearing devices will create the sheared composition to improve the binding ability in the pelleting mills, as well as allow for additional moisture to be released in the downstream flash conveyor prior to transferring into the pellet mill surge bin.
A surge bin may be utilized upstream from the pellet mill 108, and designed for one to two hours of retention in the event that the pellet mill 108 plugs or other unexpected issues arise that cause for temporary delays in the densification portion of the plant. The surge bin will allow the remainder of the plant to continue to operate while the blockage is cleared. From the surge bin the cellulosic by-products and coal fines mixture will convey through a pellet mill feed conveyor designed for 110% of the total capable flow which allows for continuous and maximum performance without surging the pellet mill 108. Consistent flow is desired to assure that pellet density and moisture are maintained.
The cellulosic by-products and coal fine mixture can be altered by addition of various liquid product streams to make fine adjustments to the finish quality of the pellet. The pellet mill 108 may be designed with a force feed system to improve flow into and through the mill. Once pelleted, the pellets are preferably cooled to within 5 degree F. of ambient temperature and screened to remove excessive fines in the process. The coal fines can be recycled back to the flash conveyor to allow for full usage and a second run through densification and cooling process. The cooled and properly sized pellets are transferred to storage or use.
The Tables below are only representative of some aspects of this disclosure. It will be understood by those skilled in the art that processes as set forth in the specification can be practiced with a variety of alterations with the benefit of the disclosure. These examples and the procedures used therein should not be interpreted as limiting the invention in any way not explicitly stated in the claims.
The invention has been shown and described above with the preferred embodiments, and it is understood that many modifications, substitutions, and additions may be made which are within the intended spirit and scope of the invention. From the foregoing, it can be seen that the present invention accomplishes at least all of its stated objectives.
