Abstract:
A method of generating syngas as a primary product from renewable feedstock, fossil fuels, or hazardous waste with the use of a cupola. The cupola operates on inductive heat alone, chemically assisted heat, or plasma assisted heat. Cupola operation is augmented by employing carbon or graphite rods to carry electrical current into the metal bath that is influenced by the inductive element. The method includes the steps of providing a cupola for containing a metal bath; and operating an inductive element to react with the metal bath. A combination of fossil fuel, a hazardous waste, and a hazardous material is supplied to the cupola. A plasma torch operates on the metal bath directly, indirectly, or in a downdraft arrangement. Steam, air, oxygen enriched air, or oxygen are supplied to the metal bath. A pregassifier increases efficiency and a duct fired burner is added to a simple cycle turbine with fossil fuel augmentation.

Description:
RELATIONSHIP TO OTHER APPLICATIONS 
       [0001]    This patent application is a continuation-in-part patent application of PCT/US2012/024726, filed on Feb. 10, 2012, which is based on Provisional Patent Application U.S. Provisional Patent Application Ser. No. 61/526,248 filed Aug. 22, 2011 and claiming the benefit of U.S. Provisional Patent Application Ser. No. 61/463,022 filed on Feb. 10, 2011 and U.S. Provisional Patent Application Ser. No. 61/525,708 filed on Aug. 19, 2011. 
     
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    This invention relates generally to systems for generating heat and power, and more particularly, to an inductive and plasma based system that generates Combined Heat and Power using multiple back up modes of operation. 
       Description of the Related Art 
       [0003]    Combined Heat and Power (hereinafter, “CHP”) systems, as well as plasma based systems, are known. Although these two types of known systems have been combined in simple arrangements, such as internal combustion based systems, there is a need for a system that achieves the benefits and advantages of both such technologies. 
         [0004]    It is, therefore, an object of this invention to provide a system the achieves the benefits of Combined Heat and Power systems, and plasma based systems. 
         [0005]    It is another object of this invention to provide a cost-effective, commercially viable, renewable CHP system. 
       SUMMARY OF THE INVENTION 
       [0006]    The foregoing and other objects are achieved by this invention which provides, a method of producing CHP, the method including the steps of: 
         [0007]    providing a cupola for containing a plasma source.; 
         [0008]    providing an inductive element; 
         [0009]    providing a metal bath in the cupola; and 
         [0010]    delivering a feedstock to the cupola. 
         [0011]    In accordance with a specific illustrative embodiment of the invention, the feedstock is a fossil fuel. In other embodiments, the feedstock is a hazardous waste, and in still further embodiments, the feedstock is a combination of any organic compound, fossil fuel, or hazardous material. 
         [0012]    In one embodiment, there is further provided the step of operating the inductive element to react with the metal bath to generate syngas. Additionally, there is provided the step of supplementing the step of operating an inductive element by the further step of operating a plasma torch. A plasma torch is operated on the metal bath, in one embodiment, selectably directly and indirectly. In some embodiments, the step of operating a plasma torch is performed in a downdraft arrangement, and in yet further embodiments, the step of operating a plasma torch is performed at an angle other than vertical. 
         [0013]    There is provided the further step of supplementing the step of operating an inductive element by performing the further step of injecting steam to enhance the production of syngas. The step of operating an inductive element is supplemented by performing the further step of injecting a selectable one of air, oxygen enriched air, and oxygen. In a further embodiment, there is provided the further step of supplementing the step of operating an inductive element by performing the further step of conducting electrical energy via a conductive rod formed of a selectable one of graphite and carbon into the metal bath. 
         [0014]    In accordance with a further method aspect of the invention, there is provided a method of producing CHP, the method including the steps of: 
         [0015]    providing a cupola for containing a metal bath; and 
         [0016]    operating an inductive element to react with the metal bath to generate syngas. 
         [0017]    In one embodiment of this further method aspect there is provided the step of providing the syngas to a duct fired burner, which may also be termed an “afterburner,” to produce steam. In some embodiments of the invention, the step of providing the syngas to a duct fired burner to produce steam includes the further step of providing natural gas to the duct fired burner. In some such embodiments, the mix of syngas to natural gas delivered to the duct fired burner or simple cycle turbine ranges between 0% to 100%. 
         [0018]    In an advantageous embodiment, there is provided the step of generating steam from the duct fired burner, and there is provided the further step of generating steam from a heat recovery system, the steam from the duct fired burner and the heat recovery system being provided to a steam turbine to make electricity. 
         [0019]    In yet another embodiment of the invention, the mix of syngas to fossil fuel delivered to the duct fired burner or simple cycle turbine ranges between 0% to 100%. 
         [0020]    In a still further method aspect of the invention, there is provided a method of producing CHP, the method including the steps of: 
         [0021]    providing a cupola for containing a metal bath; 
         [0022]    operating an inductive element to react with the metal bath; and 
         [0023]    supplementing the step of operating an inductive element by the further step of operating a plasma torch and a pregassifier. 
         [0024]    In yet another aspect of the invention, there is provided a method of producing CHP, the method including the steps of: 
         [0025]    providing a cupola for containing a metal bath; 
         [0026]    operating an inductive element to react with the metal bath; and 
         [0027]    supplementing the step of operating an inductive element by the further step of propagating a selectable one of plasma and electricity into the metal bath to supplement heating of the cupola by the step of operating an inductive element with a pregassifier and a turbine generator and a heat recovery system (hereinafter, “HRS”). 
         [0028]    In a still further method aspect of the invention, there is provided a method of producing CHP, the method including the steps of: 
         [0029]    providing a cupola for containing a metal bath; 
         [0030]    operating an inductive element to react with the metal bath; and 
         [0031]    supplementing the step of operating an inductive element by the further step of propagating a selectable one of plasma and electricity into the metal bath to supplement heating of the cupola by the step of operating an inductive element with a pregassifier and a turbine generator which is augmented with a duct fired burner before the HRS. 
         [0032]    In a further embodiment the duct fired burner maybe run on 100% syngas or a blend of a fossil fuel and syngas that could range to 100% fossil fuel. The turbine maybe run on 100% syngas or a blend of fossil fuel that may range to 100% fossil fuel. The steam generated by the duct fired burner and HRS is, in some embodiments, sold as thermal power or used to power a second steam turbine in a conventional duct fired burner augmented combined cycle generation system. 
         [0033]    In one embodiment, there is provided the further step of supplementing the step of operating an inductive element by performing the further step of conducting electrical energy via a conductive rod formed of a selectable one of graphite and carbon into the metal bath. 
         [0034]    In a further embodiment, the pregassifier has multiple stages. The first stage of the gassifier is heated by steam and the second stage is heated by higher temperature steam, air, molten salt, or any other high temperature heat transfer medium. 
         [0035]    In accordance with a method aspect of the invention, there is provided a method of producing combined heat and power with the use of inductive furnace technology, and optionally with plasma assisted heat with direct, or indirect applications of energy. Additionally, the method of the present invention optionally employs downdraft assisted plasma energy. In accordance with a specific illustrative embodiment, the method of the present invention produces heat via an inductive heating element by exciting and heating a metal bath in a cupola. The metal bath is used, in some embodiments, to produce syngas alone as a heat source or it is supplemented by a plasma torch system. In some embodiments, the cupola is used to process renewable feedstocks, fossil fuels, or hazardous materials. The heat required to produce syngas is, in some embodiments, supplemented by injection of air, oxygen enriched air, or oxygen into the cupola. The syngas process is also supplemented, in some embodiments, by the injection of steam to the cupola. 
         [0036]    The system is configured in a novel way to yield extremely high overall efficiency. A combination of common production components and a high efficiency system design are incorporated in a novel way to achieve the goal of a low cost CHP system. The feedstock to run the operation in some embodiments, is a renewable fuel such as Municipal Solid Waste (hereinafter, “MSW”), biomass, algae, or fossil fuels. 
         [0037]    The invention utilizes the high temperature syngas produced by the inductive plasma process with a simple cycle turbine operating at its maximum fuel inlet temperature. A duct fired burner is located at the outlet of the turbine and before a HRS. The fuel for the duct fired burner is delivered to the system at the maximum allowable temperature. The high velocities, elevated temperatures, available oxygen, and mixing characteristics at the turbine outlet before the duct fired burner promote high efficiency in the duct fired burner and exceptionally high efficiency in the HRS for steam production. The overall system efficiency in some embodiments of the invention is over twice that of conventional coal steam generators in use today. 
         [0038]    In a further embodiment the duct fired burner maybe run on 100% syngas or a blend of a fossil fuel and syngas that could range to 100% fossil fuel. The turbine maybe run on 100% syngas or a blend of fossil fuel that may range to 100% fossil fuel. The steam generated by the duct fired burner and HRS maybe sold as thermal power or may be used to power a second steam turbine in a conventional duct fired burner augmented combined cycle generation system. 
         [0039]    The novel addition of natural gas in the system also allows for redundancy and scalability in the system. The steam output is be tripled in many cases by the additional injection of natural gas or other fossil fuels to the duct fired burner. In some embodiments of the invention the turbine has its syngas-derived fuel sweetened with the natural gas, if necessary. Finally an advantageous use of pregassifiers is utilized in the system to boost the overall plant efficiency and attain the goal of a cost effective production facility. 
         [0040]    The inventive system also takes incorporates the use of inductive baths with direct acting, indirect acting, and down draft, plasma assist. Additionally, the system of the present invention incorporates a duct fired burner application on the outlet of the simple cycle turbine to improve system efficiency. The steam generated by the duct fired burner and HRS may be sold as thermal power or may be used to power a second steam turbine in a conventional duct fired burner augmented combined cycle generation system. 
         [0041]    In accordance with yet a further method aspect of the invention, there is provided a method of producing combined heat and power, the method including the steps of: 
         [0042]    providing a cupola for containing a metal bath; 
         [0043]    operating an inductive element to react with the metal bath to generate syngas; and 
         [0044]    providing the syngas to a duct fired burner to produce steam. 
         [0045]    In one embodiment of this yet further method aspect, the step of providing the syngas to a duct fired burner to produce steam includes the further step of providing natural gas to the duct fired burner. 
         [0046]    In some embodiments, the steam that is generated from the duct fired burner and the HRS are utilized by a steam turbine to make electricity. 
         [0047]    The mix of syngas to fossil fuel that is delivered to the duct fired burner or to the simple cycle turbine ranges between 0% to 100%. In other embodiments, the mix of syngas to natural gas delivered to the duct fired burner or simple cycle turbine ranges between 0% to 100%. 
     
    
     
       BRIEF DESCRPTION OF THE DRAWING 
         [0048]    Comprehension of the invention is facilitated by reading the following detailed description, in conjunction with the annexed drawing, in which: 
           [0049]      FIG. 1  is a simplified schematic representation of a cupola arrangement constructed in accordance with the invention; 
           [0050]      FIG. 2  is a simplified schematic representation showing in greater detail a lower portion of the cupola of  FIG. 1 ; 
           [0051]      FIG. 3  is a simplified schematic representation showing an indirect application of a plasma torch on an inductive metal bath and the cupola; 
           [0052]      FIG. 4  is a simplified schematic representation showing a second indirect application of a plasma torch disposed at an angle relative to the cupola; and 
           [0053]      FIG. 5  is a simplified schematic representation of a specific illustrative embodiment of a system configured in accordance with the principles of the invention for producing combined heat and power. 
       
    
    
     DETAILED DESCRIPTION 
       [0054]      FIG. 1  is a simplified schematic representation of a cupola arrangement  100  constructed in accordance with the invention. As shown in this figure, a cupola shell  101  is provided with an inlet  104  for introducing a feedstock (not shown) that in some embodiments of the invention is a renewable feedstock, a fossil fuel, or a hazardous waste (not shown). Any combination of the three forms of feedstock can be used in the practice of the invention. There is additionally provided in an outlet port  106  for enabling removal of the generated syngas (not shown). In contrast to conventional inductive furnaces that facilitate a large outlet for metal or alloy production, there is no other outlet for such product. There is an additional small drain  110  for eliminating inorganic slag. 
         [0055]    It is a feature of the present invention that primarily organic compounds are processed to produce syngas. The specific illustrative embodiment of the invention described herein is essentially a bucket arrangement wherein an indirect electrical arc services a non-transfer inductive furnace. This is distinguishable from the conventional use of an inductive furnace, which is to make metals and alloys. 
         [0056]      FIG. 1  further shows cupola arrangement  100  to have a direct acting plasma torch  115 , which in some embodiments of the invention, as will be described below in relation to  FIGS. 3, and 4 , is an indirect acting plasma torch, to assist in the cupola heating process. In other embodiments, plasma torch  115  is a carbon or graphite rod that is used to conduct AC or DC electrical energy into a metal bath  120 . The return path for the electrical energy has been omitted from this figure for the sake of clarity. 
         [0057]    There is provided in this specific illustrative embodiment of the invention a cathode  122  that is coupled electrically to an inductive element  125 . Additionally, inductive element  125  has associated therewith an anode  127 . 
         [0058]    Air, oxygen enriched air, or oxygen are injected into cupola arrangement  100  via an inlet  130  to assist in the generation of heat using chemical energy and steam that is delivered via an inlet  132 . The chemical energy and steam are injected for the further purpose of assisting in the generation of syngas. The process of the present invention can, in some embodiments, be performed in a pyrolysis, or air starved, mode of operation. 
         [0059]      FIG. 2  is a simplified schematic representation showing in greater detail a lower portion of cupola arrangement  100  of  FIG. 1 . Elements of structure that have previously been discussed are similarly designated. Inductive element  125  reacts on metal bath  120 . Metal bath  120  can consist of any metal or alloy such as aluminum for low temperature work or titanium for high temperature work. Metal bath  120  is kept at a constant fill level  134  by operation of slag drain  110  through which a slag product  135  is drained. 
         [0060]      FIG. 3  is a simplified schematic representation showing a cupola arrangement  200 , wherein there is illustrated an indirect application of a plasma torch  115  on an inductive metal bath and the cupola for enhancing the heating process. In this specific illustrative embodiment of the invention, plasma torch  115  has a power capacity of 0.2 MW. Elements of structure that have previously been discussed are similarly designated. As shown in this figure, syngas outlet  106  is lengthened in this specific illustrative embodiment of the invention, and is shown to have vertical and horizontal portions,  106   a  and  106   b , respectively. Indirectly acting plasma torch  115  is, in this embodiment, inserted in the end of vertical section  106   a . In this specific illustrative embodiment of the invention, syngas outlet  106  is refractory-lined and insulated (not shown). 
         [0061]    In the embodiment of  FIG. 3 , there is shown an inlet  107  via which is provided municipal solid waste (MSW) (not specifically designated) as a feedstock. Of course, other types of feedstock, as hereinabove noted, can be used in the practice of the invention. 
         [0062]    The product syngas in this embodiment is forced to exit into vertical section  106   a  where it communicates with the high temperature plume (not specifically designated) and the radiant heat that is issued by plasma torch  115 . The syngas and syngas outlet  106  both are heated by operation of plasma torch  115 . In this specific illustrative embodiment of the invention, the heated horizontal portion  106   b  of syngas outlet  106  is subjected to a heat extraction arrangement that delivers the heat to inlet  107  for the purpose of pre-gasifying the MSW feedstock. The heat extraction arrangement is formed by an impeller  210  that urges a fluid (not shown) along a fluid loop that includes a region  212  where the fluid is heated by communication with heated horizontal portion  106   b  of syngas outlet  106 . The heated fluid then is propagated to a heat exchanger  215  where a portion of the heat therein is transferred to the incoming MSW feedstock that is being delivered at inlet  107 . 
         [0063]    There is additionally shown in this figure a steam inlet  132 , as hereinabove described. However, the steam is shown in this figure to be supplied by a steam supply  220 , and the steam then is conducted to a further heat exchanger  225  where a portion of the heat in the steam is transferred to the incoming MSW feedstock that is being delivered at inlet  107 . Heat exchangers  215  and  225  thereby constitute a pre-gassifier for the MSW feedstock, whereby the production of syngas is enhanced. 
         [0064]      FIG. 4  is a simplified schematic representation of a cupola arrangement  250  showing a second indirect application of a plasma torch that is disposed at an angle relative to the cupola. Elements of structure that have previously been discussed are similarly designated. As shown in this figure, the outlet port  106  is fabricated in part at an angle that in some embodiments is greater than 90° to induce tumbling and mixing in the product syngas (not shown). Thus, in addition to vertical and horizontal portions,  106   a  and  106   b , respectively, there is shown in this specific illustrative embodiment of the invention an angular portion  106   c . Plasma torch  115  is shown to be inserted in angular portion  106   c.    
         [0065]      FIG. 5  is a simplified schematic representation of a specific illustrative embodiment of a system  500  configured in accordance with the principles of the invention for producing combined heat and power. As shown in this figure, a main feed tube  501  serves as an input for feedstock, in the form of Municipal Solid Waste  504  (“MSW”) for fueling the system. Feed tube  501  is preheated in a novel way to increase efficiency with a heat transfer system  502  that is, in the embodiment, operating on waste low pressure steam heat generated from sensible heat that is recovered from the inductive/plasma process taking place in a plasma/inductive chamber  505 . 
         [0066]    In this embodiment, sensible heat is recovered using a syngas quench system  512  that serves to generate waste heat steam  514 . This steam, which is delivered to the pregassifier along steam conduit  507 , is typically below 400° F. A second stage of pregassifier energy is provided to the feedstock to improve system efficiency, at a higher temperature at pregassifier loop  503 . Pregassifier loop  503  extracts heat from syngas  510  by operation of an impeller, such as compressor  508 , which urges a flow of heated fluid (not specifically designated) through the loop. At least a portion of the heated fluid, in this specific illustrative embodiment of the invention, is delivered to plasma/inductive chamber  505  at an input  526 . Plasma/inductive chamber  505  incorporates, in some embodiments, a cupola arrangement (not specifically designated in this figure), as described above. 
         [0067]    This added energy serves to improve overall performance by the use of waste heat recovered from sensible energy on the outlet of the plasma/inductive chamber  505 . In this case the transfer media is typically air or extreme high temperature steam. More exotic heat transfer media like molten salt are used in some embodiments. It is to be understood that the system of the present invention is not limited to two stages of pregassification heat process and transfer, as multiple such gassifier systems are used in the practice of some embodiments, of the invention. 
         [0068]    As noted, MSW  504  is used as a feedstock in this process example. Inductive coil  506  and plasma torch  509  are the primary energy sources or inputs that react with MSW  504  to produce Syngas  510 . Inductive coil  506  reacts against a molten metal bath (not shown) in plasma/inductive chamber  505 . 
         [0069]    A filter  511  and quench system  512  are portions of the emission reduction system. Sorbents (not shown) are injected and used in some embodiments, but have been omitted in this figure for sake of clarity of the drawing. The semi-processed syngas  510  is split out through conduit  513  and fed directly into a duct fired burner  517  at the highest temperature available. The balance of the syngas is fed into a compressor  515  and boosted in pressure to be fed into turbine  516 . Fossil fuel such as natural gas from pipe  523  and  525  may be mixed with the syngas in concentrations from 0 to 100%. Other fossil fuels such as, but not limited to, butane, propane, or diesel may also be used. Air (not specifically designated) enters turbine  516 , and the high temperature, high velocity, and turbulent air at the outlet (not specifically designated) of turbine  516  is boosted to a higher energy state through the added energy of duct fired burner  517 . A heat recovery system (“HRS”)  518  is shown to be in direct communication with the energy-rich outlet gas from the turbine produces steam  521 , which is sold to customers or could be routed to a low turbine (not shown) to produce electricity in a combined cycle configuration (not shown). 
         [0070]    Electrical power  523  is generated at electrical generator  527 , which as shown, receives rotatory mechanical power in this embodiment from turbine  516 . As noted electrical energy may also be generated from an additional steam turbine driven off of steam pipe  521 . Electrical output power  522  from the electrical generator is used to run the process in plasma chamber  505 . Also, electrical output power  523  or the steam turbine generated electrical power driven off of pipe  521  is available for sale to a third party. Natural gas or other fossil fuel gas is boosted into turbine  516  at input  525  to enhance performance and reliability. Natural gas or other fossil fuel energy is boosted into input  523  of duct fired burner  517 . This too enhances overall system performance and reliability. 
         [0071]    This process of the present invention also serves as a system backup if the production of syngas  510  is for any reason stopped or reduced. A second back up boiler  520  functions as a redundant steam generator to expand the production range of the facility and to add another level of redundancy to the steam production. As shown, back-up boiler  520  receives water in this embodiment at an input  530  and issues steam at an output  532 . Back-up boiler  520  is, in some embodiments, operated on syngas, fossil fuel, or a combination of both. In addition, a natural gas source  519  is shown to supply back-up boiler  520  and also serves as a boost to turbine  516  at an input  525 . 
         [0072]    Although the invention has been described in terms of specific embodiments and applications, persons skilled in the art can, in light of this teaching, generate additional embodiments without exceeding the scope or departing from the spirit of the invention described and claimed herein. Accordingly, it is to be understood that the drawing and description in this disclosure are proffered to facilitate comprehension of the invention, and should not be construed to limit the scope thereof.