Patent Application
20110119996
The present disclosure relates to renewable energy sources, and in particular, resources that do not depend on fossil fuels and that reduce emissions of “greenhouse gas” carbon dioxide into the atmosphere. More specifically, the present disclosure relates to compositions and structures for combustible biomass, or biofuel materials.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
With the recent emphasis on renewable energy sources, efforts have been made in the art to create so-called “biomass” materials, in which a combustible combination of waste, such as wood chips or sawdust, along with certain additives, are combined and processed to create an energy resource that can take the place of, or be combined with, for example, coal. A common biomass is the wood pellet, which is now subject to a standard developed by the Pellet Fuels Institute. More specifically, a “premium” oak species wood pellet provides 8810 BTU/lb, and a “standard” pine species wood pellet provides 9600 BTU/lb. Furthermore, both ash and chlorine content are provided by the standard.
Known biomass materials contain natural lignins, which are released with heat of the constituent materials in order to bind the materials together into a burnable mass. Natural lignins, for example from various wood sources, are complex natural polymers resulting from oxidative coupling of, primarily, 4-hydroxyphenylpropanoids. Additionally, other materials such as thermoplastic resins have been used to bind the constituent materials together.
However, these natural lignins and thermoplastic binders do not create a biomass that is durable for transport or other processing operations. Moreover, these biomass forms suffer from chronic crumbling and dust generation during production and downstream handling. Significant amounts of dust can become an explosive issue, and thus current binders in the art may ultimately cause safety hazards. As a further disadvantage of known binders, product uniformity is an issue, with irregular lengths and ragged cuts, which further add to the dust problem. As other materials without natural lignins are added, such as switchgrass, forest litter, paper waste, cane waste, and the like, product quality is reduced, and the dust issue often becomes more aggravated. Additionally, some of the known binders generate gases during the burning process that are environmentally undesirable, and in fact, some of the binders are not completely combusted during the burning process.
In one form of the present disclosure, a biomass fuel compact is provided that comprises a body having a combustible biomass composition and an adhesive additive, wherein the adhesive additive comprises a starch and a hydroxide.
In another form, a biomass fuel compact is provided that comprises a combustible biomass composition and an adhesive additive. The adhesive additive comprises at least one of a starch and a hydroxide.
In still another form, a biomass fuel compact is provided that comprises a body having a combustible biomass composition, an adhesive additive comprising a starch and a hydroxide, a silicate additive, and at least one of a viscosity additive and a preservative.
In variations of these biomass fuel compacts, the hydroxide is selected from the group consisting of alkali metal hydroxides, alkaline earth hydroxides, sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, and caustic soda. Further additives may also include a silicate additive, (which may be a liquid or powder form), a viscosity additive, a preservative, (which may include fungicide or biocide), and a BTU additive (which may include any combustible oil source). Additionally, various geometries and compositions for the biomass fuel compacts are also provided by the teachings of the present disclosure.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.
According to the principles of the present disclosure, a biomass fuel compact is provided that comprises a body, which may be in any shape or form, such as the exemplary forms shown in
The body 10 comprises a combustible biomass composition that can essentially be any combustible material, or combination of combustible materials, and/or their use waste. By way of example, these materials may include saw dust, cardboard and chipboard, grass, switchgrass, energy crops, hay, tree bark, sweetgum seed pods, pinecones, newsprint, wheat straw, duckweed, pine needles, mixed leaves, yard waste, agricultural waste, cotton waste, grape and wine offal, corn stover, crop stovers, peat, tobacco waste, tea waste, coffee waste, food processing waste, food packaging waste, nut meats and shells, chestnut hulls, pecan shells, animal waste, livestock waste, mammal waste, municipal solid waste, paper waste, pallets, and egg cartons.
Advantageously, the biomass fuel compact is highly durable do to its inventive adhesive additive. Generally, the biomass fuel compact uses a Stein Hall type adhesive made from starch, or any other suitable material to replace the natural lignins as set forth above. In a Stein Hall adhesive, about 5% to 20% of the total starch content is gelatinized into a high viscosity paste called primary starch. The remainder of the starch (about 80% to 90%) stays ungelatinized and is called secondary starch. The starch may be one produced from wheat, oats, rice, corn, wheat middling, wheat waste or even wood and the like, but containing a gelatinized fraction that upon substantial drying will tightly bond the biomass composition.
Additionally, the adhesive additive includes a hydroxide. The hydroxide may be, for example, alkali metal hydroxides, alkaline earth hydroxides, sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, and caustic soda, among others. The synergistic combination of starch and hydroxide provide a highly durable biomass fuel compact, in which any number of constituent combustible materials may be used, without relying on any natural lignins or other undesirable binders.
In one form, the innovative adhesive is provided to bind the constituent biomass composition and also to form a substantially continuous shell around the exterior portion of the fuel compact. With this shell, the biomass fuel compact according to the present disclosure is highly durable and significantly reduces the traditional dust issues associated with biomass compositions, as set forth above.
In one exemplary composition of the present disclosure, the biomass fuel compact comprises, by percent weight, about 69-98% biomass composition, about 1-30% starch, and less than 1% hydroxide. Another composition is about 90-95% biomass and about 5-10% of the inventive adhesive additive.
Further additives are also provided by the present disclosure, which may include, by way of example, a silicate additive, (which may be a liquid or powder form), a viscosity additive, a preservative, and a BTU additive. The silicate additive is included to provide added weather resistance and hydrogen bonding of biomass particles. The silicate may include sodium, potassium, or lithium, or mixtures of these three in one form of the present disclosure. The viscosity additive may be a naturally occurring biomass such as duckweed reduced to a flour particle size, or rice hulls, or coal dust, or any other viscosity altering substance. The preservatives may include, by way of example, fungicides, biocides, or mixtures of these two, in one form of the present disclosure. In another form, the preservative may include sodium tetraborate or borax containing compounds at a concentration of about 1 to about 5%, and more particularly, about 1 to about 2%. Moreover, sodium silicate may be added to improve water repellency and act as a biocide, along with any oil, natural or petroleum based, used motor oil, or oil derivatives as the BTU additive.
The additives may also include materials that will benefit the combustion or emission profile of the biomass. When calcium hydroxide is used as a source of hydroxide, it may react to form calcium silicate, which scavenges sulfur dioxide and nitrous oxides in air emissions from combustion in flue gas. When lithium hydroxide is used, it may react and form lithium silicate, which forms a zeolite capable of sequestering carbon dioxide from combustion gases. Furthermore, it is contemplated that the addition of a mix of alkali metal or alkaline earth hydroxides may be beneficial to the emission of undesirable gases from combustion of the innovative compacts according to the teachings of the present disclosure.
Each of the viscosity additive and the BTU additive, in one form of the present disclosure, are combustible materials. The viscosity additive, in one form, is a naturally occurring biomass such as duckweed, rice hulls, and coal dust. Furthermore, by way of example, the BTU additive is an oil or an oil derivative, either natural or petroleum based, and either new, off specification, or waste oil.
In a further exemplary composition, the biomass fuel compact comprises about 50-95% biomass, about 5-50% starch, about 0.005-0.05% hydroxide, about 0.1-5% silicate additive, and about 0.1-2% viscosity additive or preservative. In should be noted that the BTU additive may comprise about 1 to about 40% of the final fuel compact composition. Further compositions according to the teachings of the present disclosure are set forth below in Table 1, with an exemplary target value for one biomass composition that comprises grass, corn stover, or a mixture thereof, according to the teachings of the present disclosure:
According to the various compositions of the present disclosure, an energy content of about 8,500 BTU/lb is achieved with the claimed biomass fuel compact.
Referring now to
As shown, the body 20 has an upper portion 22, a lower portion 24, and tapered sidewalls 26, 28, 30, and 32 extending from the upper portion 22 to the lower portion 24, wherein the upper portion 22 is wider than the lower portion 24. In one form, the body 20 comprises rounded edges 34 as shown, in order to provide increased durability. The tapered sidewalls 26 and 28 are generally parallel and opposed as shown, as are the tapered walls 30 and 32. At least one of the tapered sidewalls 26, 28, 30, and 32 defines a flat surface in one form of the present disclosure. Additionally, the body 20 may define an aperture 40 formed therethrough in another form of the present disclosure. This aperture 40, which is shown in this exemplary form as a hole, is provided to increase the surface area to facilitate dry-down of the compact and also to improve the rate of combustion. It should be understood that this geometry, along with the pellet, puck, and briquette as previously set forth, are merely exemplary and should not be construed as limiting the scope of the present disclosure.
Accordingly, a composite biomass fuel compact is provided by the present disclosure that is durable, that reduces the amount of dust normally associated with known biomass compositions, that is lower cost, higher efficiency, and reduces and/or improves regulated or unregulated emissions. The innovative adhesive tends to not only bind the composite biomass, but also to form a substantially continuous shell around the exterior of the compact, providing for a highly durable composite biomass fuel compact.
Various forms of composite biomass fuel compacts described herein were tested for durability per the American Society of Agricultural and Biological Engineering ASABE S269.4, December 1991 (R2007) Sec. 5 Durability test standard. A “GAMET” Pellet durability test was utilized to run the testing experiments for 10 minutes@ 50 rpm at room temperature. A Pellet Durability Index (PDI) was defined by dividing the weight of the compacts before and after testing. After testing, the compacts are screened and the remaining whole compacts are weighted. The starting weight is standardized at 500 grams. The PDI equals the remainder after testing divided by 500 multiplied by 100 to arrive at a percentage. The test results are as follows:
1. Premium “wood” fuel pellet, manufactured by “Greenway” MFG by Hassell and Hughes, Collinwood, Tenn. 38450—PDI=93.88.
2. Switchgrass Puck, manufactured by local providers, without any adhesive—PDI=68.4.
3. Innovative composite biomass fuel compact according to the teachings of the invention—PDI=99.99. (Using saw dust)
BTU content was tested using a bomb calorimetry, Model IKA c2000 basic. The test method was ASTM D5865, standard test method for Gross Calorific value of Coal and Coke. Five variations of the innovative composite biomass fuel compact were tested for BTU content. The results were as follows:
1. Corn Stover mixed with animal waste−BTU content=6,942 BTU/lb
2. Mixed biomass (mixture of agricultural fibers)−BTU Content=7,893 BTU/lb
3. Mixed biomass in Sample 2, with addition of BTU booster (hydraulic fluid)−BTU content=10,137 BTU/lb.
4. Corn Stover pellet in Sample 1, with addition of BTU booster−BTU content=11, 908 BTU/lb.
It should be noted that the invention is not limited to the various forms described and illustrated as examples. A large variety of modifications have been described and more are part of the knowledge of the person skilled in the art. These and further modifications as well as any replacement by technical equivalents may be added to the description and figures, without leaving the scope of the protection of the disclosure and of the present patent.
This application is based upon Provisional Patent Application Ser. No. 61/336,989, entitled “Improved Biomass Fuel Pellet,” filed Jan. 29, 2010, the contents of which are incorporated herein by reference in their entirety and continued preservation of which is requested. This application is also related to the application “Biomass Fuel Compact Processing Method” filed concurrently herewith, which is commonly assigned with the present application, and the contents of which are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61336989 | Jan 2010 | US |
