Patent Application
20100071602
The present disclosure relates generally to the field of waste disposal. More specifically, the present disclosure relates to systems and methods for disposing of food waste.
In certain embodiments, a processing facility disposes of food waste in an environmentally undisruptive manner. The processing facility can convert food waste materials into one or more bio-energy or bio-fuel products. The processing facility can include a plurality of processing modules that are interrelated such that one or more outputs from one module are directed to one or more other modules within the processing facility. In some embodiments, the interrelation of the processing modules is substantially balanced such that during operation, the processing facility consumes relatively small amounts, or even no amount, of one or more process resources (e.g., electricity, water, and natural gas) from outsides sources.
The drawings depict only illustrative embodiments, and are, therefore, not to be considered to be limiting of the scope of the disclosure. Various embodiments will be described and explained with specificity and detail with reference to the accompanying drawings, in which:
It will be readily understood that the components of the embodiments as generally described and illustrated in the figures herein could be arranged and designed in a wide variety of different configurations. For example, some embodiments can include fewer than all components shown in an illustrated embodiment, while other embodiments can include more components. Thus, the following more detailed description of various embodiments, as represented in the figures, is not intended to limit the scope of the disclosure or claims.
With reference to
In certain embodiments, the processing facility 100 can convert at least a portion of a food waste stream 130 into one or more bio-energy or bio-fuel products. For example, in the illustrated embodiment, the processing facility 100 produces ethanol, bio-diesel, and electricity from separate portions of the food waste stream 130. Other useful products can also be produced, such as, for example, glycerin and fertilizer ash.
The processing facility 100 can be substantially process energy self-sustaining. For example, in some embodiments, once the process modules are operational (e.g., once the fluidized bed combustion module 120 is hot enough to combust feedstock delivered thereto), the processing facility 100 generates sufficient amounts of electricity from the food waste stream 130 to maintain its own operation. The processing facility 100 can generate the electricity substantially without receiving energy from sources other than the food waste stream 130, such as from an external power grid. In further embodiments, the processing facility 100 can generate excess amounts of electricity, which can be delivered to an external power grid. As further discussed below, in some embodiments, process steam generated by the processing facility 100 from the food waste stream 130 can be used to power equipment within the processing facility 100, and can contribute to the process energy self-sustainability of the processing facility 100.
As also discussed below, in some embodiments, the processing facility 100 can be substantially self-sustaining with respect to the production and use of process steam for a variety of applications in addition to or in place of powering machinery, and in further embodiments, can produce excess process steam. In some embodiments, the processing facility 100 can be substantially self-sustaining with respect to water usage, and in further embodiments, can produce excess water.
With continued reference to
In particular, the receiving module 110 can direct the food waste stream 130 into one or more of a feedstock that comprises food waste having a fats content above a fats threshold value, as depicted at block 142; a feedstock that comprises food waste having a fats content above a fats threshold value and a carbohydrates content above a carbohydrates threshold value, as depicted at block 144; a feedstock that comprises food waste having a carbohydrates content above a carbohydrates threshold value, as depicted at block 146; and a feedstock that comprises food waste having a fats content below a fats threshold value and a carbohydrates content below a carbohydrates threshold value, as depicted at block 148. The term “food waste” is a broad term used herein in its ordinary sense, and it includes solid food products (e.g., solid foods or processed foods, such as breads, pastries, vegetables, and meats), liquid food products (e.g., beverages), solids and liquids used in the preparation of food products (e.g., beer waste, frying oils, and wash down water), edible or inedible byproducts from the manufacture of processed foods, and inedible portions of food products (e.g., fruit pits, and carrot tops) for which disposal is desired. Food waste can be generated by a variety of sources, such as, for example, dairy processing facilities, meat processing facilities, bakeries (small-scale or industrial), and individual households. The term “fats” is a broad term used herein in its ordinary sense, and it includes oils (e.g., vegetable oils), fats (e.g., animal fats), and greases (e.g., animal greases). The term “carbohydrates” is a broad term used herein in its ordinary sense, and it includes complex carbohydrates (e.g., starches) and simple carbohydrates (e.g., sugars).
The above-threshold fats feedstock 142 and/or the above-threshold fats/carbohydrates feedstock 144 can be delivered to the rendering module 112 for further processing. The above-threshold carbohydrates feedstock 146 can be delivered to the carbohydrates processing module 116 for further processing. The below-threshold fats/carbohydrates feedstock 148 can be delivered directly to the fluidized bed combustion module 120 as a fuel source.
As shown at block 150, recyclable materials can also be separated from the food waste stream 130, which can provide a source of revenue for the processing facility 100. As shown at block 152, process wastewater from the receiving module can be delivered directly to the anaerobic digestion module 118. The process wastewater 152 can include, for example, excess water contained within the food waste stream 130.
The rendering module 112 can be configured to separate feedstock material received therein into a fats component, as shown at block 156, and a defatted feedstock component, as shown at block 158. The fats 156 can be delivered to the fats processing module 114 for further processing. The defatted feedstock 158 can be delivered to either or both of the carbohydrates processing module 116 and the fluidized bed combustion module 120, depending on the carbohydrates content of the defatted feedstock 158. For example, if some or all of the defatted feedstock 158 comprises a carbohydrates content above a threshold value, the defatted feedstock 158 can be delivered to the carbohydrates processing module 116 for further processing, and if some or all of the defatted feedstock 158 comprises a carbohydrates content below the threshold value, it can be delivered to the fluidized bed combustion module as fuel. As depicted at block 159, process wastewater can be delivered from the carbohydrates processing module 116 to the anaerobic digestion module 118.
As previously mentioned, the carbohydrates processing module 116 can receive feedstock having a carbohydrates content above a threshold value from one or more of the receiving module 110 (see, e.g., block 146) and the rendering module 112 (see, e.g., block 158). As shown at block 160, the carbohydrates processing module 116 can be configured to produce ethanol from the feedstock thus received (e.g., via fermentation), which can provide a revenue stream for the processing facility 100. As depicted at block 162, process wastewater from the carbohydrates processing module 116 can be delivered to the anaerobic digestion module 118. As depicted at block 163, excess condensate from the carbohydrates processing module 116 can be delivered to the water treatment module 123.
As depicted at block 164, the carbohydrates processing module 116 can produce one or more distiller coproducts that are delivered as fuel to the fluidized bed combustion module 120. For example, the distiller coproducts can include distiller cake and concentrated solubles that can be combusted in the fluidized bed combustion module 120. The distiller coproducts 164 can be dewatered prior to being delivered to the fluidized bed combustion module 120.
As previously mentioned, the fats processing module 114 can receive fats 156 from the rendering module 112. As shown at blocks 166 and 168, respectively, in some embodiments, the fats processing module 114 is configured to produce bio-diesel and glycerin from the fats 156. The bio-diesel 166 and the glycerin 168 can each provide a revenue stream for the processing facility 100. As depicted at block 170, process wastewater from the fats processing module 114 can be delivered to the anaerobic digestion module 118. As depicted at block 172, the fats processing module 118 can also yield defatted feedstock that is delivered to the fluidized bed combustion module 120.
As previously discussed, the anaerobic digestion module 118 can receive process wastewater from one or more of the receiving module 110, the rendering module 112, the fats processing module 114, and the carbohydrates processing module 116. From the process wastewater thus received, the anaerobic digestion module 118 can yield clean graywater, as depicted at block 174; sludge, as depicted at block 176; and bio-gas, as depicted at block 178. At least a portion of the clean graywater 174 can be delivered to the carbohydrates processing module 116 and may be used, for example, as make-up process water in the fermentation process. Likewise, at least a portion of the clean graywater 174 can be delivered to the water treatment module 123 for further processing. The sludge 176 can be dewatered and delivered to the fluidized bed combustion module 120 as fuel, and water that is removed from the sludge 176 can be returned to the anaerobic digestion module 118. The bio-gas 178 can be delivered to the fluidized bed combustion module 120 as fuel. As further discussed below, the bio-gas 178 can be selectively delivered to the fluidized bed combustion module 120 as a supplement to other feedstock to help maintain operation of the fluidized bed combustion module 120
As previously discussed, the fluidized bed combustion module 120 can receive feedstock fuel from one or more of the receiving module 110 (see, e.g., block 148), the rendering module 112 (see, e.g., block 158), the fats processing module 114 (see, e.g., block 172), the carbohydrates processing module 116 (see, e.g., block 164), and the anaerobic digestion module 118 (see, e.g., blocks 176 and 178). From the feedstock thus received, the fluidized bed combustion module 120 can yield process heat, as depicted at block 182, stack exhaust, as depicted at block 181, and ash, as depicted at block 180. The ash 180 can be utilized, for example, as high quality fertilizer or construction fill material, or in the manufacture of cement. The ash 180 thus can provide a revenue stream for the processing facility 100. As further discussed below, the stack exhaust 181 can comprise or can consist essentially of carbon dioxide and water. For example, the stack exhaust 181 can include only small or trace amounts of other gases or particulates.
The steam processing module 122 can be coupled with the fluidized bed combustion module 120 and can utilize heat 182 generated by the fluidized bed combustion module 120. In some embodiments, the steam processing module 122 uses the heat 182 to produce high-pressure steam, as depicted at block 184. The steam processing module 122 can utilize the high-pressure steam 184 to produce electricity, as depicted at block 188, and low-pressure steam, as depicted at block 186. In some embodiments, at least a portion of the electricity 188 (e.g., electricity in excess of that used to operate the processing facility 100) generated by the steam processing module 122 is delivered to an external power grid 190, and can provide a source of revenue for the processing facility 100.
At least a portion of the electricity 188 generated by the steam processing module 122 can be delivered to an internal power grid, schematically depicted by a dashed line 192, that services the processing facility 100. In particular, as depicted by arrows directed inwardly from the internal power grid 192, each of the receiving module 110, the rendering module 112, the fats processing module 114, the carbohydrates processing module 116, the anaerobic digestion module 118, the fluidized bed combustion module 120, the steam processing module 122, and the water treatment module 123 can be connected to and receive electricity from the internal power grid 192. As illustrated by a dashed line, the internal power grid 192 can also be connected to the external power grid 190 so as to deliver excess electricity thereto.
At least a portion of the low-pressure steam 186 generated by the steam processing module 122 can be delivered as process steam to a process steam distribution system, schematically depicted by a dashed line 194, that services the processing facility 100. For example, as depicted by arrows directed inwardly from the process steam distribution system 194, each of the receiving module 110, the rendering module 112, the fats processing module 114, and the carbohydrates processing module 116 can be connected to and receive process steam from the process steam distribution system 194. In certain embodiments, the process steam can be used to heat portions of the various processing modules. In some embodiments, the process steam can be used to drive mechanical equipment, such as, for example, centrifuges and compressors, and can reduce the overall electricity consumption of the processing facility 100. Portions of the processing facility 100 in addition to or other than those listed above can receive process steam via the process steam distribution system 194 as needed or desired
As previously mentioned, the water treatment module 123 can receive condensate 163 from the carbohydrates processing module 116 and/or clean graywater 174 from the anaerobic digestion module 118. In some embodiments, the water treatment module 123 can receive fresh water from an outside water source, as depicted at block 196, such as a well, a municipal water supply, or any other suitable water source. The water treatment module 123 can be configured to purify the water received therein to yield clean water 197 suitable for use as boiler water and/or as clean process water.
The clean water 197 can be delivered to a water distribution system, schematically depicted by a dashed line 198, that services the processing facility 100. The water distribution system 198 can be connected directly to the fresh water source 196, and the clean water 197 can be used to supplement or replace water delivered from the source 196. As depicted by arrows directed inwardly from the water distribution system 198, each of the fats processing module 114, the carbohydrates processing module 116, and the steam processing module 122 can be connected to and receive clean water 197 from the water distribution system 198. Additional or other portions of the processing facility 100 can receive clean water 197 via the water distribution system 198, such as, for example, the water treatment module 123 itself, the receiving module 110, and/or the rendering module 112, as needed or desired.
Embodiments of the processing facility 100 and components thereof will now be described in greater detail. With reference to
The mixed MSW 202 can comprise food waste interspersed with other solid waste materials, and can be transported from residential, commercial, and industrial food processors, warehouses, and/or other points of origination in a conventional manner, or in any manner that hereafter becomes conventional. The mixed MSW 202 can be delivered to the tipping floor module 212 and separated using techniques presently known in the art or any techniques which become available hereafter.
The mixed MSW 202 can be sorted into at least four separate feedstock streams. For example, depending on its fats and carbohydrates content, the mixed MSW 202 can be directed into one or more of the above-threshold fats feedstock 142, the above-threshold fats/carbohydrates feedstock 144, the above-threshold carbohydrates feedstock 146, and the below-threshold fats/carbohydrates feedstock 148. As previously mentioned, the above-threshold fats feedstock 142 and the above-threshold fats/carbohydrates feedstock 144 can be delivered to the rendering module 112 to remove fats therefrom, and the defatted feedstock 158 can be delivered to the carbohydrates processing module 116 depending on its carbohydrates content (see
In certain embodiments, it can be undesirable to introduce fats into the carbohydrates processing module 116, and in such cases, the above-threshold carbohydrates feedstock 146 that is delivered directly to the carbohydrates processing module 116 can be substantially free of fats content. In other embodiments, the above-threshold carbohydrates feedstock 146 can include fats, as discussed further below with respect to
Portions of the mixed MSW 202 that comprise food waste having fats content above a fats threshold value can be directed into the stream of above-threshold fats feedstock 142 or the above-threshold fats/carbohydrates feedstock 144, depending on the carbohydrates content of the MSW. If the fats content is at or below the fats threshold value, the portions of mixed MSW 202 can be directed into the stream of below-threshold fats/carbohydrates feedstock 148.
The fats threshold value can be a dynamic or variable value that is selected or otherwise determined based on one or more factors, which can include the desired inputs for and/or the desired outputs from the processing facility 100, and which can vary depending on logistical, efficiency, economic, commercial, and/or regulatory considerations. For example, if bio-diesel is in higher demand than electricity, the fats threshold value can be set relatively low such that more food waste is processed through both the rendering module 112 and the fats processing module 114 to obtain a greater amount of bio-diesel 166, and such that fewer fats are delivered directly to the fluidized bed combustion module 120 for conversion to electricity. Similarly, if electricity is in higher demand than bio-diesel, the fats threshold value can be set relatively high such that less food waste is processed through the rendering module 112 and the fats processing module 114 and such that more fats are combusted in the fluidized bed combustion module 120.
A minimum fats threshold value can be dependent on the efficiency of the rendering module 112. For example, if the rendering module 112 is unable to efficiently separate fats from feedstock having a fat content of less than about 3% fats by weight, the minimum fats threshold value may be set somewhat higher than 3% fats by weight to a level at which a usable amount of fats is separated from the feedstock via the rendering module 112. For example, the minimum fats threshold value may be set at about 5% fats by weight. The fats threshold value at which the processing facility 100 actually operates may be scaled upwardly from the minimum threshold value depending on such factors as the costs associated with operating the rendering module 112, the costs of commodities used in operating the fats processing module 114 (e.g., methanol), the opportunity costs lost by consuming electricity generated via the steam processing module 122 or water purified via the water treatment module 123 to operate the fats processing module 114, and/or the selling price of bio-diesel or glycerin. For example, if the minimum fats threshold value is about 5% fats by weight, the actual fats threshold at which the processing facility 100 operates in various embodiments can be no less than about 5%, no less than about 10%, no less than about 15%, no less than about 20%, or no less than about 25% fats by weight, depending on factors such as those just described. Moreover, the operational fats threshold value can be adjusted as one or more of these factors changes.
In some cases, the fats threshold value may be set relatively high, or simply may not be used, to permit faster processing of the mixed MSW 202 through the receiving module 110. For example, the operational fats threshold value can effectively be set at 100% such that all of the mixed MSW 202 that contains fats is directed to the below-threshold fats/carbohydrate feedstock 148, thereby eliminating the amount of sorting to which the MSW 202 is subjected, which can speed up the processing of the mixed MSW 202. Stated otherwise, in some embodiments, the mixed MSW 202 is not sorted based on fats content such that substantially all fats contained in the mixed MSW are passed to the fluidized bed combustion module 120 as fuel. For example, the operational fats threshold value may effectively be set at 100% if many trucks filled with mixed MSW 202 are lined up and waiting for access to the tipping floor sub-module 212, or in the case of a emergency in which generation of as much electricity as possible is desired.
Portions of the mixed MSW 202 that comprise food waste having both fats content above the fats threshold value and a carbohydrates content above a carbohydrates threshold value can be directed into the above-threshold fats/carbohydrates feedstock 154. Like the fats threshold value, the carbohydrates threshold value can be dynamically changing value that is selected or otherwise determined based on a variety of factors, such as those mentioned with respect to the fats threshold value. For example, if ethanol is in higher demand than electricity, the carbohydrates threshold value can be set relatively low such that more food waste is processed through the carbohydrates processing module 116 to obtain a greater amount of ethanol, and such that the amount of carbohydrates burned in the fluidized bed combustion module 120 is reduced. In various embodiments, a minimum carbohydrates threshold value can be a carbohydrates content of about 10% carbohydrates by weight, and an operational carbohydrates threshold value can vary so as to no less than about 10%, no less than about 15%, no less than about 20%, no less than about 25%, or no less than about 30% carbohydrates by weight based on factors such as those described above with respect to the fats threshold value.
In some embodiments, the carbohydrates threshold is applied to the defatted feedstock 158 (see
Portions of the mixed MSW 202 that comprise food waste having a small or insignificant fats content and a carbohydrates content above the carbohydrates threshold value can be directed into the stream of high carbohydrates feedstock 156. As discussed below with respect to
In some cases, the carbohydrates threshold value may be set relatively high to permit faster processing of the mixed MSW 202 through the receiving module 110. For example, the carbohydrates threshold value can effectively be set at 100% such that all of the mixed MSW 202 is directed to the below-threshold fats/carbohydrates feedstock 148, thereby eliminating the amount of sorting to which the MSW 202 is subjected, which can speed up the processing of the mixed MSW 202. Stated otherwise, in some embodiments, the mixed MSW 202 is not sorted based on carbohydrates content such that substantially all carbohydrates contained in the mixed MSW are passed to the fluidized bed combustion module 120 as fuel.
Food waste having a fats content below the fats threshold value and a carbohydrates content below the carbohydrates threshold value can be directed into the stream of low fats/low carbohydrates feedstock 158.
With continued reference to
In some embodiments, as depicted at block 220, supplemental feedstock material can be separated from the mixed MSW 202 and directed to the fluidized bed combustion module 120 for use as fuel. The supplemental feedstock 220 can include organic materials such as, for example, yard waste, farm waste, and paper. The supplemental feedstock 220 can be used as a supplemental fuel source when feedstock derived from food waste runs low or contains a relatively small energy content (e.g., has a low BTU content).
With continued reference to
As with the mixed MSW 202 described above, the segregated waste 204 can be separated into one or more of the feedstock categories that are based on the fats content and the carbohydrates content of the food waste within the feedstock (e.g., feedstocks 142, 144, 146, and 148). Similarly, recyclable materials 150, undesirable combustion materials 218, and/or supplemental feedstock 220 can be sorted from the segregated waste 204, as described above.
With continued reference to
Depackaging various types of packaged food waste 206 can yield one or more revenue streams for the processing facility 100 that are separate from the bio-energy products harvested from the food waste. For example, some or all of the packaging removed from the packaged food waste 206 can be recycled. Additionally, in some governmental jurisdications, excise taxes that previously have been levied on cases, kegs, bottles, or cans of beer, wine, or other spirits can be rebated for destroying the food items.
As with other sources of the food waste stream 130 described above, the depackaged food waste can be separated into one or more of the feedstock categories that are based on fats and carbohydrates content of the food waste within the feedstock (e.g., feedstocks 142, 144, 146, and 148). Similarly, undesirable combustion materials 218 and/or supplemental feedstock 220 can be sorted from the packaging materials, as described above.
With continued reference to
In some instances, the liquid food waste 208 can be delivered from the liquid food waste receiving sub-module 216 directly to the rendering module 112 or the carbohydrates processing module 116 (see
In further instances, the liquid food waste 208 may have a fats content or a carbohydrates content that is below a fats or carbohydrates threshold value. In certain of such instances, the liquid food waste 208 can be delivered directly to the anaerobic digestion module 118.
As shown in
With reference again to
In certain embodiments, the fats processing module 114 can comprise any of a variety of fats processing systems known in the art, or any other suitable fats processing systems that may yet be devised. For example, in some embodiments, the fats processing system 114 comprises a bio-diesel plant configured to produce fuel-grade bio-diesel from fats removed from foods. The fats processing system 114 can comprise a glycerin recovery unit. The fats processing system 114 can include pretreatment, process equipment, storage, and load out sub-modules.
In certain embodiments, the carbohydrates processing module 116 can comprise any of a variety of carbohydrates processing systems known in the art, or any other suitable carbohydrates processing systems that may yet be devised. For example, in some embodiments, the carbohydrates processing system 116 comprises an ethanol plant configured to produce fuel-grade ethanol from feedstock having a high carbohydrates content via fermentation and distillation. The carbohydrates processing module 116 can include cook, fermentation, distillation, dehydration, evaporation, storage, and load out sub-modules.
In some embodiments, the carbohydrates processing module 116 is highly efficient with respect to water usage. For example, in various embodiments, a majority of, or even substantially all of, the water in which carbohydrates are fermented by the carbohydrates processing module 116 is obtained from the food waste stream 130 (e.g., from liquid food waste 208 shown in
In some embodiments, the carbohydrates processing module 116 can include a chiller that uses a refrigerant, which can also reduce the water consumption of the carbohydrates processing module. The carbohydrates processing module 116 can thus be significantly more efficient with respect to water usage than other ethanol plants, such as those that evaporate high volumes of water as blowdown water in cooling towers. Process steam generated by the steam processing module 122 can be used to operate the chiller (e.g., pumps and/or compressors), and can reduce electricity consumption of the carbohydrates processing module 116.
In certain embodiments, the carbohydrates processing module 116 can function substantially without discharging water outside of the processing facility 100. For example, rather than discharging excess thin stillage to a water treatment plant outside of the processing facility 100, or to tankers for transport outside of the processing facility 100 for use as fertilizer, the carbohydrates processing module 116 can deliver the excess thin stillage to the anaerobic digestion module 118.
In some instances, rather than processing some or all of the process wastewater 162 from the carbohydrates processing module 116 via the anaerobic digestion module 118 and/or the water treatment module 123, the process wastewater 162 can be mixed with feedstock to form a slurry and delivered to the fluidized bed combustion module 120. In many instances, it can be desirable to deliver wastewater having a high salts content to the fluidized bed combustion module 120 in this manner. The salts can be included in the ash 180 produced by the fluidized bed combustion module 120.
As previously mentioned, the anaerobic digestion module 118 can produce bio-gas 178, sludge 176, and clean graywater 174 from the process wastewater it receives. Substantially all of the bio-gas 178, which generally comprises primarily methane and carbon dioxide, can be combusted in the fluidized bed combustion module 120. Combustion of methane, which is recognized as a potent greenhouse gas, and other bio-gases in this manner can prevent the release of greenhouse gases into the atmosphere.
The sludge 176 can be partially dewatered and sold as fertilizer. The sludge 176 can also be used as fuel for the fluidized bed combustion module 120. For example, in some embodiments, the sludge 176 produced by the anaerobic combustion module 120 can be dewatered to comprise between about 15% and about 20% solids by weight. The sludge 176 can then be mixed with other feedstock having a higher solids concentration such that the overall solids concentration of the sludge mixture is increased to a suitable level for combustion in the fluidized bed combustion module. In other embodiments, the sludge can be at least partially dewatered prior to delivery to the fluidized bed combustion module 120.
The clean graywater 174 produced by the anaerobic combustion module 120 can be delivered to the water treatment module 123 to remove organics, salts and other dissolved solids, and other materials that may be undesirable (e.g., for water that is to be used in a boiler). In some embodiments, the clean graywater 174 can be delivered to the carbohydrates processing module 116 without further processing.
The fluidized bed combustion module 120 can comprise a fluidized bed combustion chamber configured to operate at high temperatures and to combust materials that come into contact with a fluidized bed of heated material. For example, the fluidized bed can comprise fluidized silica that is heated to a temperature such that it is particularly suited to reduce or eliminate the amount of nitrous oxide produce during combustion. In various embodiments, the fluidized bed combustion module 120 can combust materials having a solids concentration by weight of at least about 20% or at least about 30% depending on the energy content present in the feedstock.
In many embodiments, the fluidized bed combustion module 120 can be substantially self-sustaining once operational. For example, in some embodiments, sources of energy from outside of the processing facility are used to initialize the fluidized bed combustion module 120. Such outside sources can include one or more of natural gas and electricity. Once the fluidized bed combustion module 120 is sufficiently hot to combust feedstock introduced therein, it can be run substantially continuously on only the feedstock delivered to it from the food waste stream 130. For example, once operational, the fluidized bed combustion module 120 can continue to operate without receiving natural gas or electricity from the external grid 190 as inputs.
Different feedstock materials are comprised of different energy content, thus the feed rate and selection of materials delivered to the fluidized bed combustion module 120 can be adjusted to maintain substantially continuous operation of the combustion module 120. Different feedstock materials can be blended to achieve a mixture that contains a relatively uniform energy content and that can maintain relatively consistent and continuous operation of the fluidized bed combustion module 120.
As an example, in some cases, bio-gas 178 can be delivered to the fluidized bed combustion module 120 as a supplement to other feedstock material having a higher energy content, but which is delivered to the combustion module 120 in small amounts. The bio-gas 178 can be introduced to the fluidized bed combustion module 120 to compensate for lower delivery rates of other feedstock materials to the fluidized bed combustion module 120.
Operation of the fluidized bed combustion module 120 can be substantially undisruptive to the environment. For example, the fluidized bed combustion module 120 can be clean-burning, which may result from limitation of the feedstock delivered thereto to organic materials. The fluidized bed combustion module 120 can produce substantially only heat as a coproduct and stack exhaust and ash as byproducts. The stack exhaust can primarily comprise, or can consist essentially of, water and carbon dioxide. The fluidized bed combustion module 120 can be configured to burn off volatile organic compounds. As previously discussed, the receiving module 110 can be configured to remove undesirable materials from the feedstock delivered to the combustion module 120 that otherwise would produce noxious exhaust gases or contaminate the ash. Additionally, in many embodiments, the feedstock introduced to combustion module 120 can be primarily organic material such that operation of the combustion module 120 is substantially carbon neutral, or stated otherwise, substantially does not provide a net increase in greenhouse gases. For example, carbon dioxide generated in the combustion of agricultural plants and animal products, which may be released in the stack exhaust 181, is generally regarded as “greenhouse neutral.”
In some embodiments, one or more processing modules can be vented to the fluidized bed combustion module 120. For example, in some embodiments, air from the receiving module 110, the fats processing module 114, the carbohydrates processing module 116, and/or the anaerobic digestion module 118 can be vented to the fluidized bed combustion module 120. Bacteria and other odor sources within the air can thus be burned off. Additionally, resultant sulfur and nitrogen compounds can beneficially fall out into the ash 180.
The steam processing module 122 can comprise a boiler, a steam turbine, a generator, and a pollution control system. As is known in the art, the steam processing module 122 can utilize a boiler to create high-pressure steam from the heat produced by the fluidized bed combustion module 122. In some embodiments, the high-pressure steam drives the steam turbine and is stepped down to low pressure steam. A generator can generate electricity from the activated steam turbine.
The water treatment module 123 can be configured to purify water via sand filtration, membrane filtration, and/or reverse osmosis. Numerous other suitable water-processing techniques are also possible.
In some embodiments, no water, or very little water, is delivered to the water treatment module 123 from the outside fresh water source 196. The water treatment module 123 thus can aid in the substantially self-sufficiency of the processing facility 100 with respect to water usage. In some embodiments, the processing facility 100 can be balanced to be a net producer of clean water 197 such that excess clean water 197 can be sold or otherwise delivered outside of the processing facility 100. For example, in some embodiments, water derived from the food waste stream 130 can be delivered to the anaerobic digestion module 118, which can process the water into clean graywater 174 that is delivered to the water treatment module 123 for further processing into clean water 197 suitable for boiler water or process water.
As previously mentioned, in some embodiments, it can be advantageous to process substantially all process wastewater produced within the processing facility 100 via the anaerobic digestion module 118 and/or the water treatment module 123. The processing facility 100 can operate substantially without discharging any wastewater outside of the processing facility 100. In other embodiments, it may be more profitable to discharge, rather than re-use, the wastewater. In certain of such embodiments, the wastewater can be treated by the anaerobic digestion module 118 and then directed to outside water disposal or additional water treatment systems.
As previously mentioned, the processing facility 100 can be operated in a highly-efficient and substantially self-sustaining manner. The production capacities of each processing module can be matched to the size and content of the inputs thereto (e.g., the food waste stream 130) such that the processing facility 100 can maintain substantially continuous and profitable operation. Moreover, the processing facility 100 can be adapted or adjusted based on the desired outputs therefrom, such as the amounts of products (e.g., bio-diesel, glycerin, ethanol, electricity, low-pressure steam, water, ash), coproducts (fats, bio-gas, sludge), or byproducts (e.g., stack exhaust). Balance can also be achieved among the processing modules with respect to the respective inputs (e.g., feedstock, electricity, process steam, process water) and outputs (e.g., altered feedstock or coproducts) of each module.
In some embodiments, a balance among the various processing modules of the processing facility 100 can be substantially static. For example, the size and content of the food waste stream 130 can be substantially consistent and predictable such that operation of the processing modules is also consistent or follows a regular pattern.
In other embodiments, achieving balance among the constituent processing modules so as to maintain substantially continuous operation of the processing facility 100 can be achieved dynamically. For example, the size and composition of the food waste stream 130 may vary significantly over time. As the food waste stream 130 varies, the processing facility 100 can adapt by delivering the food waste stream 130 to the appropriate processing modules, each of which can yield suitable feedstock for the fluidized bed combustion module 120. For example, the fats processing module 114 can produce defatted feedstock 172 having a high energy content, and the anaerobic digestion module 118 can produce bio-gas 178 having a relatively low energy content. The processing facility 100 can be sufficiently adaptable to maintain substantially continuous operation of the fluidized bed combustion module 120, despite variations that may arise in the food waste stream 130. For example, if only small amounts of high energy feedstock is available, combustion of the high energy feedstock can be supplemented with biogas. Similarly, plant-based yard waste, agricultural waste, and/or paper waste can be used to supplement feedstock derived from the food-waste stream.
As previously discussed, dynamic balancing can also be achieved by varying the fats threshold and/or the carbohydrates threshold to thereby adjust the relative amounts of bio-diesel, ethanol, and/or electricity being produced by the processing facility 100. The processing facility 100 can be dynamically balanced to increase a net output of bio-diesel, glycerin, ethanol, ash, electricity, low-pressure steam, and/or clean-water. Similarly, the processing facility can be dynamically balanced to curtail the production of bio-diesel, glycerin, ethanol, ash, electricity, low-pressure steam, clean-water, and/or stack exhaust.
In further embodiments, the relative sizes and capacities of the various processing modules of the processing facility 100 can be tailored to a known set of inputs or outputs. For example, in some geographic regions (e.g., tropical islands), the food waste stream 130 may predominantly comprise food wastes from the production of sugar, molasses, or rum that have a high carbohydrate content. The processing facility 100 thus can have a relatively larger carbohydrates processing module 116 to allow for greater amounts of ethanol production. In some geographic regions, it may be desirable to generate electricity, minimize water consumption, and/or curtail stack exhaust emissions, and the balance of the processing facility 100 can be adjusted accordingly.
As previously discussed, the processing facility 100 can be substantially electrically self-sustaining such that electricity derived from a food waste stream 130 is substantially sufficient to maintain operation of the processing facility once the fluidized bed combustion module 120 is operational. Additionally, use of process steam to drive motors, compressors, and other equipment of the processing modules can reduce the electricity consumption of the processing facility 100 and thereby increase its net electricity production. Similarly, the processing facility 100 can also be balanced and substantially self-sufficient with respect to process water consumption and/or process steam production and use, or can be a net producer of process water and/or process steam.
The processing facility 100 can be operated profitably due to a variety of factors. For example, landfills often consider food products as undesirable and, and often restrict or prohibit disposing of food product in the landfill, or may charge higher tariffs for such disposal. This can especially be true for large quantities of food waste, such as for food that is dated, spoiled, recalled, contaminated, or damaged. By accepting as feedstock food waste that is generally undesirable and often difficult and expensive to dispose of, or even prohibited from disposal in certain landfills, the processing facility 100 can utilize food waste in lieu of commoditized feedstock commonly used to produce bio-fuels, such as soybeans or corn, and can eliminate the commercial or commodity risks associated therewith.
In some embodiments, the processing facility 100 can be located at or near a landfill site to enable the ready interception of food waste that is already destined for the landfill. The food waste thus can be delivered to the processing facility 100 at little to no additional transportation cost to a waste carrier. In some embodiments, the processing facility 100 charges a smaller fee for access to a tipping floor of the processing facility 100 than would be charged to permit tipping of the food waste at a landfill.
MSW carriers often provide the services of collection, transportation, and tipping at published rates, which can generally be stable over long time periods, and may even be are mandated by local governments and regulatory agencies. Agreements reached between an MSW carrier and its customers under such long-term tariff rates can ensure both the future supply of feedstock for the processing facility 100 and the future costs (if any) for the feedstock.
Any or all of the foregoing factors can contribute to a profitable processing facility 100. For example, by eliminating the use of commodity feedstock and the commercial or commodity risks associated therewith, by being self-sufficient with respect to process energy, and/or by limiting water requirements, the processing facility 100 can be substantially financially isolated from fluctuations in various commodities markets. Additionally, the processing facility can produce multiple and diversified income streams. Examples of income streams can include sales of ethanol, bio-diesel, glycerin, and electricity, which can be primary sources of income in some embodiments. In further embodiments, secondary sources of income can include sales of fertilizer or construction ash, sales of recyclables, de-packaging disposal fees, MSW tipping fees, waste water and liquid food waste disposal fees, and, in some cases, government “green” energy credits and tax incentives, such as “carbon credits” that are currently available in some governmental jurisdictions.
In various embodiments, the processing facility 100 can provide one or more additional benefits. For example, with respect to landfills, the processing facility 100 can extend the life of the landfills; reduce odors, diseases, putrid organics, vermin, and insects; reduce bio-hazard and water pollution sources; and reduce the risk of fires. The processing facility 100 can have a low impact on water supplies, such as may result from utilizing the high water content present in waste foods, by efficient use of excess process steam for both heating and cooling, by recycling water via the anaerobic digestion module, and by operation of a dedicated water treatment module. The destruction of spoiled, recalled, or damaged food products can also eliminate the so-called “cradle-to-grave” risk that can be associated with such products. Further, the processing facility 100 can be balanced so as to meet or exceed any environmental regulations imposed on the processing facility 100 by one or more governmental bodies.
In addition to the foregoing environmental benefits, the outputs of the processing facility 100 can be substantially undisruptive to the environment. For example, the stack exhaust from the processing facility 100 can meet or exceed environmental regulations, the ash can be clean and free of heavy metals, and the bio-fuels can be clean-burning and substantially carbon-neutral.
In further embodiments, the fats processing module 314 can be configured to produce biodiesel and glycerin from the fats 156. Based on such factors as the commodity price of materials used in the manufacture of biodiesel and glycerin (e.g., methanol and caustic) and/or the selling price of biodiesel or glycerin, the processing module 314 can be configured to produce either the oil 169 or biodiesel and glycerin, depending on which is more profitable.
The processing facility 300 can further include a carbohydrates processing module 316, such as the carbohydrates processing module 116, which is configured to separate fats 165 from an above-threshold carbohydrates feedstock 146. For example, in some cases, the above-threshold carbohydrates feedstock 146 can comprise a fats content by weight that is less than a given fats threshold value at which the processing facility 300 is operating. Processing the above-threshold carbohydrates feedstock 146 via the carbohydrates processing module 316 significantly, or substantially completely, reduces the carbohydrates content of the feedstock 146 such that the distiller coproducts 164 (see
Without further elaboration, it is believed that one skilled in the art can use the preceding description to utilize the present disclosure to its fullest extent. The examples and embodiments disclosed herein are to be construed as merely illustrative and not a limitation to the scope of the present disclosure in any way. It will be apparent to those having skill in the art that changes may be made to the details of the above-described embodiments without departing from the underlying principles of the disclosure described herein.
Additionally, any suitable combination of the features of one or more embodiments is possible. For example, one or more of the fats processing module 314 and the carbohydrates processing module 316 of the processing facility 300 can replace the corresponding fats processing module 114 and/or carbohydrates processing module 116 of the processing facility 100. Similar substitutions can be made with some or all of the respective components of the processing facilities 100, 300, 400, 500, 600. Where like or similar components are disclosed in multiple embodiments, the description of those components with respect to one embodiment can apply to the other embodiments as well. Various modifications and improvements of the embodiments specifically disclosed in the description above are within the scope of the disclosure and appended claims.
This application claims the benefit of U.S. Provisional Application No. 61/099,838, which was filed on Sep. 24, 2008, and of which the entire contents are hereby incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 61099838 | Sep 2008 | US |
