US20140101990A1

US20140101990A1 - Process and System For Manufacturing Consistent BTU Value Of Solid Fuel From Solid Waste

Info

Publication number: US20140101990A1
Application number: US13/802,478
Authority: US
Inventors: William F. Rhatigan; Gerard J. O'Brien
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-04-20
Filing date: 2013-03-13
Publication date: 2014-04-17

Abstract

A method for manufacturing solid fuel, including estimating a heat value for at least a portion of a combustible waste stream. At least one type of combustible polymer is added to the combustible waste stream as needed to raise the estimated heat value of the portion of combustible waste stream to a desired heat value. The combustible waste stream is heated and mixed while adding a binder to the combustible waste stream to increase the structural integrity of a solid fuel formed from the mixed combustible waste stream. The heated and mixed combustible waste stream is pressed into briquettes of solid fuel which are substantially hydrophobic.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-In-Part of U.S. patent application Ser. Nos. 13/090,349 and 13/090,356 filed Apr. 20, 2011 and claims priority to U.S. Provisional Application Nos. 61/325,941 and 61/325,946 filed Apr. 20, 2010 and U.S. Provisional Application No. 61/620,939 filed Apr. 5, 2012.

FIELD OF THE INVENTION

This invention relates to the conversion of Residential Solid Waste (RSW), optionally with selected elements of Municipal Solid Waste (MSW), to a solid fuel that has a consistent BTU value.

BACKGROUND OF THE INVENTION

While recycling of MSW has increased dramatically over the last 15 years through incentives and community education, MSW itself has grown in volume during that same period to over 220 million tons in North America alone. Recycling has increased 42% during this period, but has plateaued at approximately 30% of the total waste. This problem has affected municipalities, states and the federal government, from a financial, as well as capacity of volume perspective. Landfilling is the prominent way of disposing of MSW. This presents significant problems for municipalities including present landfills are at or near capacity, and they are faced with significant post-closure costs and maintenance. There is a lack of new land for landfilling and, even where land is available, permitting processes are expensive and time-consuming, and the social issue of not in my backyard (NIMBY) exists.
Currently, waste to energy (WTE) is the most prevalent method for addressing both issues. In WTE, the MSW is directly placed into the boiler and incinerated with heavy metals falling through the grate to be recaptured in the bottom ash. Due to the varying nature of MSW, the moisture content is in excess of 20%, with an average British Thermal Unit (BTU) value of between 4,500-6,000 BTU's. As EPA regulations become more detailed and geared to reducing air pollution, the WTE field is faced with a very costly solution of emission reduction. Typically specialized bag collectors and scrubbers are installed at a very steep capital expense.
WTE facilities have had limited success in reducing emissions, and enhancing BTU values. Source separation is one method for enhancing the BTU value and refuse derived fuel (RDF) is another method of increasing BTU value of fuel. RDF or more commonly called ‘fluff’, is a product that has been separated and shredded after being screened for metals and glass. The resulting product is finely ground to produce a loose “fluff”. This product is blown into boilers to reduce moisture and increase BTU. This is usually produced onsite or within a short distance, as the product cannot be exposed to moisture, rain, etc. These factors render the RDF a very ineffective low value fuel. One process for preparing a combustible pellet from fluff is disclosed by Philipson in U.S. Pat. No. 7,252,691.
Biogas systems have seen a greater use in the United States, typically in segments of a landfill that has been capped. Biogas produces a methane gas from the decomposing waste. Although this produces a limited amount of methane, the reduction of MSW to a landfill is 0%, and does not provide front end value.
Anaerobic digestion is a method of producing methane gas using organic waste streams from MSW. Organic waste is subject to a specialized decomposition process and the resultant gas is put through the Fisher/tropics process to remove impurities. Although effective is producing various quality gases, the solids used are typically 90-98% of the input waste, which must be landfilled. The process is effective is producing economic value, but does not optimize waste reduction.
Plasma arc gasification and fluidized bed or coal gasification are other methods of utilizing the waste stream in reducing the amount landfilled. Plasma arc is still in development stage and has limited commercial success. Development continues to produce a commercial product and has little impact on reducing the waste stream. Fluidized bed gasification, has been used commercially by the coal industry for a number of years. Fluidized bed boilers use a technique where pulverized coal is burned in various levels of the boilers, resulting in a more complete burn, and effecting emissions on a limited basis. Currently the technology is utilizing coal only as its feedstock and has no significant impact on the waste stream.
There is an unmet need for a fuel that will utilize the majority of post recycled waste stream. While various conventional processes use mainly light and organic fractions of the waste stream, the majority of the waste stream still needs to be landfilled. The majority of RSW (residential solid waste) commonly referred to as the “green or white bags” currently is collected and immediately landfilled. The focus of reducing disposal quantities in significant volumes of MSW can be solved by manufacturing a high BTU value (10,000-13,000 BTU's) solid fuel that can be consumed exclusively or be co-fired with either coal or biomass.
Typically the majority of engineered fuels are produced through a pelletizing system. These systems include the pelletizer and methods of receiving raw MSW, with separations and grinding techniques, then feeding the actual pelletizing machines. The average pelletizing machine is typically limited to 3-5 tons per hour of production. Once the pellet is created it is subject to a cooling chamber to solidify the pellet. To achieve an effective commercial production rate of 25 tons per hour, a minimum of 5 systems would be deployed, resulting in an extremely capital intensive operation. Pelletizing also produces pellets that are subject to degradation and structural changes to the pellet. To prevent moisture absorption, the majority of pellets need to be siloed, which requires capital expenditure for the plant. Pellet applications are more prevalent in the biomass industry, using mainly agricultural components to make up the blend of feedstock.
Certain fuel pellets and production processes are disclosed by Johnston in U.S. Pat. No. 4,236,897, by Waif et al. in U.S. Pat. No. 5,387,267, by Myasoedova in WO1999/055806, and by Parkinson et al. in U.S. Pat. No. 6,165,238. More recent solid fuel disclosures are provided by Bohling et al. in U.S. Patent Publication No. 2010/0018113 and by Calabrese et al. in U.S. Pat. No. 8,349,034. Other engineered fuels are disclosed by Benson et al. in U.S. Pat. No. 5,429,645, by Eley et al. in U.S. Patent Publication No. 2008/0202993, by Gold et al. in U.S. Patent Publication No. 2009/0090282, and by Richey et al. in U.S. Patent Publication No. 2011/0162264. Processing of waste streams is discussed by Morrison in U.S. Pat. No. 5,888,256 and by Bohling et al. in U.S. Patent Publication No. 2010/0038594.
It is therefore desirable to have a consistent fuel that utilizes RSW as well as various post recycled fractions of MSW, especially for the coal industry, as well as for some biomass operators.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved solid fuel from a solid waste stream which can be utilized in current boilers and burners without retrofitting.
Another object of the present invention is to provide such a solid fuel which is substantially impervious to water and is easy to handle and store.
This invention features a method for manufacturing solid fuel, including removing non-combustible and hazardous materials from a waste stream of substantially solid materials to produce a substantially combustible waste stream, and estimating a heat value for at least a portion of the combustible waste stream. At least one type of combustible polymer is added to the combustible waste stream as needed to raise the estimated heat value of the portion of combustible waste stream to a desired heat value. The combustible waste stream is heated and mixed while adding a binder to the combustible waste stream to increase the structural integrity of a solid fuel formed from the mixed combustible waste stream. The heated and mixed combustible waste stream is pressed into briquettes of solid fuel which are substantially hydrophobic.
In some embodiments, the binder also increases the hydrophobic properties of the briquettes, and the binder includes at least one organic material. In certain embodiments, the binder is heated to a temperature between 200 degrees F. to 350 degrees F. at least during mixing with the combustible waste stream. In a number of embodiments, the waste stream of substantially solid materials is obtained from at least one of residential solid waste and municipal solid waste. In some embodiments, the desired heat value for the combustible waste stream is between 10,000 BTU to 13,000 BTU. This invention also features briquettes of solid fuel made by one or more of the above embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

In what follows, preferred embodiments of the invention are explained in more detail with reference to the drawings, in which:

FIG. 1 is a diagram of one embodiment of the present invention;

FIG. 2 is a diagram of initial processing to make solid fuel according to the present invention;

FIGS. 3A and 3B are diagrams of further processing to make solid fuel according to the present invention;

FIG. 4 is a schematic block diagram of a system and method according to the present invention;

FIG. 5 is a more detailed block diagram of a system according to the present invention;

FIG. 6 is a still more detailed diagram of a system according to the present invention with a plant control system; and

FIG. 7 illustrates an improved manufacturing process according to the present invention;

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

This invention may be accomplished by a system and method which performs thermodynamic analysis on a waste feedstock stream, adds material to adjust at least the BTU or other heat value, mixes the adjusted feedstock with at least one binder, and then directs the mixed feedstock into at least one briquetting machine to produce fuel having a substantially consistent BTU value and other preselected parameters as desired.
Preferably, the waste stream is initially subjected to a novel process of taking the raw RSW (residential solid waste) and selected MSW (municipal solid waste), as received at a facility. A novel, sophisticated manufacturing process according to the present invention preferably includes: separation, shredding, one or more optional drying steps such as by microwaving, dynamic analysis during manufacturing, and a specialized binding process, to produce a solid fuel. The resultant process preferably produces a solid shape of fuel, such as a rounded briquette, that is consistent in BTU value (such as 10,000-13,000 BTU's), is hydrophobic, is capable of being mass produced (preferably at least 30 tons per hour), is capable of being transported by rail, barge or truck hauling, produces significantly reduced emissions as compared to coal or current biomass, exhibits minimal leaching, and can be co-fired with coal and/or biomass such as in either coal or biomass boilers.
In other words, fuel according to the present invention typically is derived primarily from RSW, which has been processed in such a manner that most inerts and metals have been removed. Further processing removes elements that potentially create environmental issues, resulting in a desirable combustible waste stream designated as “WERC-2 Mix” in FIG. 1 that is mixed, heated, and preferably pressurized, to form an engineered solid fuel that will provide equivalent or higher fuel value compared to coal and most current biomass alternatives. The final solid fuel product preferably is a briquetted fuel with one or more of a variety of final shapes, which is hydrophobic and may be stored outside without degradation and shipped in the same manner as coal. The order and techniques that comprise the finishing step preferably are capable of mass production. The final finishing process preferably utilizes commercially available equipment from various industries.
One manufacturing process 10, illustrated schematically in FIG. 1, utilizes solid waste processed as described in more detail below to become WERC-2 Mix, step 20, and is further ground or shredded as needed to reduce particle size to below three inches in average diameter, preferably below one inch. The mixture is heated and compressed, step 40, and coated and/or mixed with recycled resin, step 50, which may utilize multiple delivery of resin, steps 52 and 54, through multiple injection ports. Sources of recycled resin, which serves as a binder in some processes according to the present invention, include water bottles and other non-chlorinated plastics. Ram-type compression against a steel brace 60 is depicted in FIG. 1 to schematically illustrate pressurized formation of a final solid fuel shape 70 such as a cylinder labelled WERC-2 MRDF, also referred to as MEFF (Manufactured Engineered Fuel Feedstock). Solid fuels 70A, 70B, 70C, 70D, and 70E, each of which may weigh one ton or more, are shown in storage, awaiting transport. After arrival at a combustion site, the entire MEFF can be burned as a single, log-type unit, or sliced or ground into pieces of desired shapes and sizes.
Manufactured solid fuel according to the present invention preferably is produced to significantly decrease CO2, S, CH, M, SO2 and heavy metals emissions during combustion by itself or when mixed with coal or other fuels. The impact preferably is quantitative and demonstrates the effects of using the product. The finished fuel preferably has a moisture content of 7% or less. The structural composition of the fuel preferably allows for a non-crushing capability while being handled or mixed. The fuel preferably requires no modifications of the existing boilers; in other words, no retrofit is required before using the fuel.
The current invention utilizes a change in design and preferably is suitable to produce commercial quantities of at least 35-50 tons per hour. A blend or mix of the final feedstock preferably has specific parameters that ensure a stable, replicable product. The manufacturing line that supplies the final feedstock typically incorporates: screening, crushing, shredding, sifting such as wind sifting, potentially drying via microwave or other energy source, separation of ferrous from non-ferrous materials using devices such as magnets and eddy currents, as well as specialized optical/vision equipment to analyze the feedstream. The object of the manufacturing line is to remove virtually all non-combustible and potentially hazardous materials such as metal, glass, selected inerts, PVC, mercury, chlorine, heavy metals, etc. from the waste stream.
One system 100 according to the present invention, FIGS. 2-3B, has a receiving area 80 with railroad tracks 82 or other transportation system, doors with X-ray equipment 84 to detect rejectable items, liquid drains 86, 88, 90 and 92, hazardous materials bunkers 94 and 96, and oil-water separator 98 leading to a water treatment plant 99. Receiving area 80 also has negative air filtration closed- loop systems 102 and 104 in this construction. A plant control room 110 preferably receives inputs in this construction from at least heat sensors 112 to detect hot spots caused by spontaneous combustion or other potential thermal problem, ion mobility spectroscope 114 to detect certain particulate matter, carbon nanotube gas ionization sensors 116 to detect certain poisonous gases, xenobiotic detection system 118 to detect various chemicals, and enzyme detector 120 to detect certain toxins and furans. Incoming RSW, MSW, construction and demolition waste, commercial waste and/or other solid waste is screened and sorted based on sensor and human input. The solid waste is initially ground by pre-shredder 132 and then passed to a long parts separator 130 where pipes, gutters, boards, shafts and other elongated items are removed. Waste density is analyzed, density control 122, and manual sorting occurs at sort table 134. The heat value of the waste is determined by optical sensors and/or manual input to BTU data base 136. Further sorting occurs in production area 138 by screen 140, preferably removing items below two inches in diameter for additional processing by magnets 150, eddy currents 152 and specialized detectors 154 for X-ray analysis, PVC, metals and inerts detection and removal, as well as near infra-red, PVC and metals detectors 156 and 158 for heavies 141 and mediums 143 separated by air separation such as wind sifters 142 and 144, respectively. Typical quantities are indicated in FIGS. 3A and 3B in TPH (Tons Per Hour) leading to non-fuel rejects 145, FIG. 3A, ferrous metals 160, FIG. 3B, non-ferous metals 162, chlorine 164, and waste fines 166 separated by screen 168.
Useful fuel products waste streams 170 and 172, FIG. 3B, are passed through final grinders 176 and are thermodynamically analysed, step 180, before or after being combined with fuel products stream 178, which is dried by microwave 174 or other heat source in this construction. The combined fuel products waste stream 182 is collected in hopper 190, the BTU value is adjusted by additives in step 192 and mixed in step 194 leading to final process 198 including briquetting or other shape formation. In some processes according to the present invention, the ECOTAC material in hopper 190 is similar to the WERC-2 Mix of step 20, FIG. 1. Heat is applied such as by ultrasound 196, FIG. 3B. BTU adjustment 192 and heating via ultrasound 196 are controlled by plant control room 100 in this construction.
Prior to the finishing step, the use of specialized controls and software, written to accomplish the processes described herein, preferably provides not only a quality assurance and quality control function, but more importantly provides a substantially constant chemical analysis of the feedstock to identify impurities and utilizes thermodynamic analysis to establish its burning capabilities in various size and type of boilers for the fuel. This data also directs the use of additives in the product. These additives are from existing waste streams. The whole manufacturing process allows for a series of checks and balances prior to entering the final process.
For simplicity and illustrative purposes, the principles of the present invention are described below in relation to FIGS. 4-7. The combination of inorganic and organic components may be used either singularly or with multiple components to produce the new solid fuel. The compounds may be used for stabilization and integrity of the solid fuel.
A method and system 400, FIG. 4, for manufacturing solid fuel according to the present invention includes removing non-combustible and hazardous materials from a waste stream of substantially solid materials, such as described above, to produce a substantially combustible feed waste stream 402, and estimating a heat value for at least a portion of the combustible waste stream, thermodynamic analysis 404. At least one type of combustible polymer is added, step 406, to the combustible waste stream 402 as needed to raise the estimated heat value of the portion of combustible waste stream to a desired heat value, such as between 10,000 BTU to 13,000 BTU. The combustible waste stream 402 is heated and mixed in mixer 408 while adding a binder 410, such as an epoxy or a recycled resin, to the combustible waste stream to increase the structural integrity of a solid fuel formed from the mixed combustible waste stream. The heated and mixed combustible waste stream is pressed by briquetting machine 412 into briquettes 414 of solid fuel which are substantially hydrophobic.
The starting point of the present invention is the information received from the thermodynamic analysis of the feedstock which is assembled prior to final grinding. The thermodynamic analysis preferably is capable of measuring and quantifying the chemical composition of the various components of the feedstock. One system for identifying and quantifying feed stream composition includes TITECH autosort multifunctional sorting systems with DUOLINE scanning technology for visible and near infra-red wavelengths, available from Van Dyk Recycling Solutions of Stamford, Conn. By utilizing different spectral sensitivities, the atomic density of the material can be identified, preferably regardless of color, thickness, dust, or other contaminants. Different materials can be separated or sorted as desired.
It is preferred that the thermodynamic unit has the following minimum capabilities:

- perform mass balance on manufactured feedstock;
- specify pre-selected chemical and physical properties of the feedstock;
- estimate combustion of feedstock material reactions within a furnace; and
- estimate conversion of particle burnout to the loss of time of ignition for solid fuel combustion.

The use of these tools, which in one construction utilizes known look-up tables for various constituents, provides predictable data to ensure that the characteristics of the feedstock will perform to their optimum capabilities, while ensuring the ability to maintain consistency of the finished product. The present invention may be contrasted with the typical methodology for establishing the value of feedstock which is subject to outside ASTM testing laboratories, where minimum baseline values of BTU's, elemental solid and limited gases are identified. These traditional efforts only provide a baseline with limited ability to fully define the solid fuel combustion characteristics. The conventional situation relies on trial and error or “art” to manufacture the blend. In using this conventional approach the data ultimately limits the boiler operator's ability to maximize efficiency due to a variation if predictability of the fuels BTU value and resulting emissions.
In preferred constructions for systems 500 and 600 illustrated in FIGS. 5 and 6, respectively, the invention comprises the following features. The entire process is considered carbon neutral. The process may use varying sizes of equipment and the order of the process may be adjusted to meet the requirements of the BTU value and blend.
The baseline product material is established during the manufacturing process, and the results of the thermodynamic analyses prior to the final grind by grinders or shredders 502, FIG. 5, and grinders or shredders 602, FIG. 6, such as shredders available from Metso Denmark A/S, Horsens, Denmark, with weighing on weigh belts 504, 604, such as weigh belts available from Thayer Scale-Hyer Industries, Inc. of Pembroke, Mass., will determine if automated or manual addition of selected material mix is necessary to ensure the final product meets desired, pre-selected tight tolerance specifications. The type, amount and rate of additional materials to be added preferably are calculated in “real time” manually or by plant controller 610, FIG. 6, and the process controls will initiate the appropriate flow and timing of one or more additives, such as plastic chips from water bottles and other recycled polymers in surge containers 512, 612 and Styrofoam (polystyrene) in surge containers 514, 614, as “boostering” or adjusting materials to alter BTU or other values up or down as desired and to increase hydrophobicity and integrity of the final solid fuel product.
The manufacturing line preferably is designed for continuous operation for at least 20 hours per day.
All material used as additives preferably comes from the RSW waste stream or very selective municipal and/or commercial waste streams. The final grinding that occurs after the thermodynamic analyses checks for any extremely small fractions of ferrous/non-ferrous metals that may have gone through the initial manufacturing process. The ferrous/non-ferrous metal is checked for particles with a size range of 2″ maximum to ⅛″ minus. The grinding specifications produce a 2″ minus final product with 70% being able to pass through a ½″ screen. The grinding machine may be operated side by side or opposite on the vertical. In either example, the grinders need to produce a uniformed flow to the primary weigh belt, such as illustrated in FIGS. 5 and 6.
The fuel mix post final shredding moves to the primary weigh conveyer belt 504, 604. The belt moves in a clockwise position in this construction. The weigh belt measures the volume and weight of the mixture to ensure a uniform flow and minimize undesired surges or pulses of the mix into the system. The mix passes through and over an electronic loadcell 506, 606, and the data is transmitted to the plant control system 610. The electronic loadcell may be operated in continuous reading mode or can be set to measure in periodic intervals such as every 15 seconds. The primary weigh belt 504, 604 preferably has a capacity of 0-50 TPH.
The mix moves to the secondary weigh belt 520, 620 which is proceeding on the horizontal but is intersected on the vertical axis, as illustrated in FIGS. 5 and 6, by variable speed weigh belts 516, 518 and 616, 618. These belts move from the additive surge tanks. The belt preferably is elevated to a position of a minimum height of one foot above the secondary weigh belt. The surge tanks allow for the addition of various kinds of additives, which may be comprised of organic or inorganic material. With the use of two flow tanks the additives may be custom mixed to meet the requirements of the specific fuel.
The belts 516, 518 and 616, 618 preferably have a capacity of 0-10 TPH and may be operated singularly, that is, independently, or in tandem. The electronic loadcell 522, 622 located at the end of secondary belt 520, 620 provides real time data to the control system 610 and operates in the same parameters as the primary weigh belt 504, 604.
Once the additives (if required), have been added in the mixing tank, such as pug mill mixer 530, 630, mixing occurs in a heated environment, preferably with both the wall of the tank 530, 630 and the interior of auger 532, 632 heated to at least 225 degrees Fahrenheit, using recirculating hot oil in this construction. Mixing of the product allows for the additives to be blended substantially uniformly and the spread, that is, elongated length, of the mixing will control air entrapment while raising the temperature of the mix within mixers 530, 630.
The resulting heated materials provide the binding and may be comprised of organic or inorganic material. The use of two 5,000 gallon bulk binder storage tanks 540 and 541, FIG. 5, allows for the various use of binding agents; a single binder tank 640 is utilized for system 600, FIG. 6. The tanks 540, 541, 640 preferably are heated from a range of 195 degrees to a maximum of 400 degrees Fahrenheit. The temperature and time of material placed in each tank will be established to transfer the material from a solid to a somewhat liquid state. The temperature range will allow for the mix to become viscous and have the ability to be free flowing either statically or under pressure.
The binder additive moves from the bulk binder storage tanks 540, 541, 640 to the mixer 530, 630 by the use of injection in this construction. Then proceeding from the tank 540, 541, 640, the binder passes through a pressurized pump 544, 545, 644 with a specific rate and psi of the binder, which is managed by the control system 610. The pumps 544, 545, 644 preferably are variable speed and the material preferably passes through a screen to remove particles that do not have the proper viscosity. Typically the percentage of the material that produces the binding is approximately 5% of the volume used to solidify the fuel determined by a flow meter 546, 547, 646 placed after the pumps 544, 545, 644, but before the injection of the binder into the mix within mixer 530, 630. Again this data is incorporated in the control system where adjustments can be made automatically based on an established algorithm or through manual interdiction of an operator.
The binder preferably is between 200 degrees F. to 350 degrees F. upon being injected into the mixer 530, 630. Once the binder is injected the agitation of the mixture is designed to provide incorporation of at least 90% to the mix. The binding agent not only provides structural integrity to the finished product, but makes the final product hydrophobic, that is, impervious to water, allowing for ease of transportation and storage. Controllers are attached to sensors which check for temperature, air entrapment, and viscosity. Once the fuel has achieved the proper parameters it proceeds to the splitting system. The splitting system aggregates the mix into a hopper. Once in the hopper the material is divided equally into two parts. The binding agent may be comprised of organic or inorganic material and through the heating or other means, be a free flowing viscous product.
The splitter 550, 650 moves the mix by conveyor belt to the respective receiving hoppers 552, 554 and 652, 654. The mix preferably is transported between functions at a rate that prevents cooling of the product causing solidification prior to the final “briquetting” process. Each receiving hopper 552, 554 and 652, 654 feeds the material into a respective final screw feeder 556, 558 and 656, 658, which meters the rate that the material is being placed into the briquetting machine 560, 562 and 660, 662.
The briquetting machine 560, 562 and 660, 662 preferably has an operation rate of 2-25 TPH. The finished fuel briquette preferably is substantially square with tapered sides and ends. Each briquetting machine, such as those available from Koppern Equipment, Inc., Charlotte, N.C., preferably is capable of making various sizes from approximately 1″×1.5″ to a maximum of 2″×2.5″.
The briquetting process is comprised of the following components in this construction:

- Receiving tank;
- Screw Feeder;
- Roller for compaction and shape formation;
- Self-Cleaning press rollers; and
- Various screen configurations.

Upon the final mix passing through the briquetting machine, the fuel is ejected into a cooler tank 570, 670. The tank 570, 670 has circulating fluid to allow for a rapid set time for each briquette. Once the briquette is cooled it is placed on the load out conveyor 572, 672 to be stored or loaded to transportation equipment 574, 674 (truck, railcar, barge) for shipment.
FIG. 7 schematically illustrates an improved manufacturing process 700 according to the present invention. Initial RSW and/or MSW arrives by transport 702, such as by truck or railroad car, and initial recycling 704 typically removes approximately 15 percent of the total materials as PVC 706, optionally wood 708, glass 710 and metals 712, both ferrous and non-ferrous, which can be sold to recycled materials buyers 714. Arrow 720 represents processing of the remaining 85 percent of the total materials by methods and systems according to the present invention as described above, with further separation therefrom of approximately three percent of the total materials: first items 722 such as heavy metals, mercury, chromium, arsenic; second items 724 such as chlorine and selected organics, third items 726 such as metals, both ferrous and non-ferrous; and fourth items 728 such as glass and inerts, all items 722-726 preferably diverted for appropriate separate processing 730. After processing of solid engineered fuel as described above to make ECOTAC manufactured product 740, approximately two percent unusable fraction 750 of the total materials is diverted to landfill 752 or other suitable disposal. In other words, approximately 80 percent of the total solid waste arriving by transport 702 becomes usable combustible fuel 740 according to the present invention, with an even higher usable percentage when wood is added to combustible fuel 740. By comparison, after typical conventional recycling, approximately 70 percent of RSW and MSW is directed to landfills.
Although specific features of the present invention are shown in some drawings and not in others, this is for convenience only, as each feature may be combined with any or all of the other features in accordance with the invention. While there have been shown, described, and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions, substitutions, and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit and scope of the invention. For example, it is expressly intended that all combinations of those elements and/or steps that perform substantially the same function, in substantially the same way, to achieve the same results be within the scope of the invention. Substitutions of elements from one described embodiment to another are also fully intended and contemplated. It is also to be understood that the drawings are not necessarily drawn to scale, but that they are merely conceptual in nature.
It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto. Other embodiments will occur to those skilled in the art and are within the following claims.
Every issued patent, pending patent application, publication or any other reference cited herein is each incorporated by reference in their entirety.

Claims

What is claimed is:

1. A method for manufacturing solid fuel, comprising:

removing non-combustible and hazardous materials from a waste stream of substantially solid materials to produce a substantially combustible waste stream;

estimating a heat value for at least a portion of the combustible waste stream;

adding at least one type of combustible polymer to the combustible waste stream as needed to raise the estimated heat value of the portion of combustible waste stream to a desired heat value;

heating and mixing the combustible waste stream while adding a binder to the combustible waste stream to increase the structural integrity of a solid fuel formed from the mixed combustible waste stream; and

pressing the heated and mixed combustible waste stream into briquettes of solid fuel which are substantially hydrophobic.

2. The method of claim 1 wherein the binder also increases the hydrophobic properties of the briquettes.

3. The method of claim 1 wherein the binder includes at least one organic material.

4. The method of claim 1 wherein the binder is heated to a temperature between 200 degrees F. to 350 degrees F. at least during mixing with the combustible waste stream.

5. The method of claim 1 wherein the waste stream of substantially solid materials is obtained from at least one of residential solid waste and municipal solid waste.

6. The method of claim 1 wherein the desired heat value is between 10,000 BTU to 13,000 BTU.

7. Briquettes formed according to the method of claim 1.

8. A method for manufacturing solid fuel, comprising:

removing non-combustible and hazardous materials from a waste stream obtained from at least one of residential solid waste and municipal solid waste to produce a substantially combustible waste stream;

estimating a heat value for at least a portion of the combustible waste stream;

heating and mixing the combustible waste stream while adding a binder to the combustible waste stream to increase the structural integrity and increase the hydrophobic properties of briquettes formed from the mixed combustible waste stream; and

9. The method of claim 8 wherein the binder includes at least one organic material.

10. The method of claim 8 wherein the desired heat value is between 10,000 BTU to 13,000 BTU.

11. The method of claim 8 wherein the binder is heated to a temperature between 200 degrees F. to 350 degrees F. at least during mixing with the combustible waste stream.

12. The method of claim 8 wherein the binder is in a substantially free flowing viscous condition when added to the combustible waste stream.

13. Briquettes formed according to the method of claim 8.