Patent Application
20120017498
Not Applicable
Not Applicable
Not Applicable
The present invention is in the technical field solid fuels. More particularly, the present invention is in the technical field utilizing a combination of materials to produce a fuel with high caloric content in the form of small briquettes or pellets, which, upon combustion, emit minimal amounts of pollutants.
Conventional solid fuels, such as coal, biomass, and waste carboniferous materials, typically contain impurities and additional hazardous pollutants in the form of chemicals or chemical compounds varying from non-negligibly small, to minute amounts. These impurities, pollutants, or hazardous ingredients make solid fuels more costly to transport, reducing their efficiency of combustion, and causing hazardous emissions. The capture of these impurities, pollutants, or hazardous ingredients post combustion, requires complex processing and excess costs as the impurities, pollutants, or hazardous ingredients are widely disbursed in the combustion gases. Further, the coal, biomass or waste carboniferous material typically is not in suitable physical form for transport or introduction to a furnace. Often, during transportation or handling of coal and biomass, undesirable particulate or dust pollution is emitted and, while the coal, biomass or waste carboniferous material is too small to be held on the stoker grate used to introduce fuel to the furnace of a boiler. Failure to capture and contain this waste results in undesirable, as well as illegal contamination and pollution of the surroundings.
The typical practice of attempting to ignite coal and biomass in separate burners of the same furnace, where the two components are not intimately combined prior to ignition, is inefficient with unintended/undesirable results. The combustion of heterogeneous solid fuels leads to altered flame temperature profiles, slagging, combustion inefficiency, increased ash, in addition to problems with grindability, fuel flow, and corrosion.
Numerous natural and synthetic substances have been used as binders for forming/producing pellets and briquettes of coal. U.S. Pat. No. 3,966,427 teaches how to make coal briquettes using bitumen or bitumen emulsions as binders. Additional art is described in U.S. Pat. No. 5,244,473 which teaches that a binder for coal fines can be made from a phenol-aldehyde resin mixed with a polyisocyanate in the presence of a catalyst. U.S. Pat. No. 5,009,671 teaches that coal briquettes can be made by using a starch binder mixed with molasses and water. Further relevant art is described in U.S. Pat. No. 4,862,485, which teaches means for forming coal pellets by mixing coal particles with polyvinyl alcohol, calcium oxide and/or magnesium oxide and water. U.S. Pat. No. 4,738,685 teaches how to cold press coal fines with molasses, an inorganic hardening agent such as calcium carbonate, calcium phosphate, iron oxide, aluminum oxide and optionally with an acid. Additional teachings relevant, though differing from the present application can be found in U.S. Pat. Nos. 4,618,347, 4,586,936. 4,169,711 and U.S. Pat. No. 5,916,826. Patent application No. 20100162619 describes a method using a Mallard process at a pressure of 5 bar at an elevated temperature for compacting biofuels together with some limited amount of peat or lignite
The present application describes unique and novel systems and methods for obtaining calorically rich combustible briquettes, relatively free of contaminants, consisting of coal and biomass which are new and novel, not featured in the aforementioned references. The biomass can consist of algae, switch grass, wood matter, such as sawdust and/or wood chips, as well as manure to mention a number of useful components, however not limited to such biomass materials.
The present invention is a new solid fuel combining coal and biomass, and other selected carboniferous solids into a homogenous, caloric high value solid fuel. The coal must be selected and prepared to have the correct size and quality, including the moisture content and levels of pollutants. Biomass must also be selected and prepared to have the appropriate be size and quality, including moisture content and levels of pollutants. An essential factor is that the biomass be selected based on its percentage relative to volume of carbon and hydrogen. A third additional material that can be used is a binder, prepared in appropriate volumes so as to efficiently bind the coal and biomass. The coal, biomass and binder are mixed in appropriate proportions that may be delivered to a machine that forms the mixture into extrusions, pellets or briquettes, with the resultant solid fuel having more desired properties for efficient burning with substantially reduced levels of emissions. Emissions are effectively removed and captured by the kilns used in the present process. The pollutant gases can also be reprocessed since many have commercial value.
a is a shredding or chipping machine to cut the biomass into small pieces in order to be able to combine them with the crushed coal.
b shows a crusher that is used to create small pieces of coal from the original coal input.
c shows a kiln, a first such kiln used to prepare the coal by eliminating some of the moisture and unwanted polluting volatiles of the coal, a second such kiln used to prepare the biomass where the kiln removes moisture and volatiles.
d is a duct for liquefying valuable hydrocarbons emitted in heating coal in the first kiln.
e illustrates the mixing machine for combining the crushed coal after processing in the first kiln, the coal then known as coal char, the shredded biomass and the liquefied hydrocarbons emanating from a duct connected to the first kiln, with the liquefied hydrocarbons acting as a binder between the coal char and biomass.
f is a schematic of the briquetting machine which receives the mixture of coal, biomass, and the liquefied hydrocarbons, the latter acting as a binder. The briquetting machine compresses the material from the mixer through one or more dies to produce brick, briquettes or pellets.
Referring to the flow chart
Biomass 109 consisting of for example of tree thinning, forest waste, algae, crops grown for fuel, or waste from agriculture, food, or drink processing, is loaded into the biomass shredder/shredding machine 110 shown in
The contents of second kiln 111 are further transferred to the coal and biomass mixer 106 where the two sources of fuel are thoroughly mixed. In the preferred embodiment, clean coal tar from duct 104 is also transferred to the mixer 106 to act as a binder between the coal char from first kiln 103 and the biomass entering the mixer 106 from second kiln 111. The contents of the binder material from duct 104 will generally consist of coal tar, bitumen, or emulsions of such materials. Once the material in the coal and biomass mixer consisting of coal char, biomass and the liquefied coal tar from duct 104, is thoroughly combined, the content is transferred to the briquette or extruder device 107. The extruder device 107 produces the finished coal-biomass product 108 in the form of pellets or briquettes.
Referring now to 202 in
b describes coal crusher 207 where coal 206 enters the proximal end of crusher 207 and is transported from proximal to distal end of 207 by moving belt 302. The crushed coal is illustrated by 301 while the crushing mechanisms are a piston 303 extending into the interior of 207, driven in an up and down motion by a motor not explicitly shown. The crushed coal exits through 304a to which is fixedly attached open flange 304.
c illustrates the first kiln 208b and second kiln 203. Both kilns are functionally identical but with possible variations in their dimensions and the operational temperatures required for the present invention. The biomass exiting the distal end of shredder 202 enters second kiln 203 while crushed coal from the distal end of 207 enters first kiln 208b. The contents of each kiln 203 and 208b during pyrolysis is indicating by 310, consisting in kiln 208b of coal, coal char and coal volatiles, and kiln 203 of biomass and biomass volatiles. Both first and second kilns, 208b and 203 respectively, have a proximal and distal end, each with fixedly attached open flanges 307 and 311a respectively. In first kiln 208b, crushed coal enters through the fixedly attached open flange 307a by way of an airlock 307, the airlock preventing oxygen/air from entering first kiln 208b and second kiln 203. The proximal end of first kiln 208b is maintained at temperatures in the range 175 to 250 C. while the distal end is maintained at a temperature at a range of ˜350-500 C. The proximal and distal ends of second kiln 203 are maintained at a temperature range of 100-150 C. at the proximal end and a temperature range of 200-275 C. at the distal end. Temperatures are controlled by heat coils 309b wrapped around outer kiln shell 305, coils 309b attached to a control power unit (not shown) to provide heat to coils 309b. The crushed coal in kiln 208b and the shredded biomass in kiln 203 are transported from proximal to distal ends of kilns 208b and 203 respectively by means of rotation of kiln core 305 of kilns 208b and 203 by action of a helical steel rail fixedly attached to the inner kiln core 305. In first kiln 208b, hydrocarbon gases evolved in heated kiln core 305 from the crushed coal which transforms to coal char due to the heating in first kiln 208b, exit by way of airlock 308 and through the fixedly attached open flange 311a. The proximal end of both first and second kilns 208b and 203 respectively, have a low temperature volatile cleanup station 309, functioning mainly to trap water vapor, disposed at their proximal ends and a high temperature cleanup station 309a to capture high temperature volatiles such as mercury, sulfur and chlorine, mounted at the distal ends.
Referring now to
In an alternate embodiment, the gases and coal char of first kiln 208b are directed through the fixedly attached open flange at the distal end of first kiln 208b to the mixer 204 shown in
The biomass from shredder 202 is directed through the open flange fixedly attached to the distal end of shredder 202 where low temperature volatiles are taken up or entrained and treated in cleanup station 309 and high temperature volatiles are taken up or entrained by the high temperature volatile cleanup station 309a. The heat treated shredded biomass is transferred to an open end with a fixedly attached open flange of mixer 204 shown in
After mixing of biomass, coal char and liquefied hydrocarbons in mixer 204, the contents of 204 pass through the distal end of mixer 204 where the distal opening is fixedly attached to an open flange and enter the briquetting device 205 shown in
While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed.
