Abstract:
A method and system for converting low BTU synthesis gas (Syngas), and synthesis gas that has been generated in situ, into a higher BTU product while minimizing the process carbon footprint. Preferably, a plasma gassifier is used to generate the syngas. Sensible heat is recovered and applied to produce electricity. The syngas is water gas shifted to enhance hydrogen production. Gasification is performed in a pyrolysis mode of operation, a nitrogen reduced mode of operation, an oxygen enriched mode of operation, or a coke supplemented mode of operation. The syngas is delivered to a reactor to produce product. The reactor is any of a pellet style reactor, a monolith style reactor, a foam reactor, a ceramic foam reactor, an alumina oxide reactor, and an alpha alumina oxide reactor.

Description:
RELATIONSHIP TO OTHER APPLICATIONS 
       [0001]    This application claims the benefit of the filing date of U.S. Provisional Patent Application Ser. No. 61/270,820, filed Jul. 13, 2009, Conf. No. 8494 (Foreign Filing License Granted); U.S. Provisional Patent Application Ser. No. 61/270.928, filed Jul. 14, 2009, Conf. No. 5021 (Foreign Filing License Granted), each in the name of the same inventor as herein. The disclosures in the identified U.S. Provisional Patent Applications are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates generally to power generation systems, and more particularly, to a method of increasing the BTU content of Syngas, and assuring its consistent component quality, from a syngas generating system. 
         [0004]    2. Description of the Related Art 
         [0005]    In the current energy environment there is ever more desire to use renewable, or carbon neutral energy sources. In the process of using these energy sources many times Synthesis Gas or syngas is produced as a way of transferring chemical energy. For many reasons syngas to date has had a difficult time making its way into production of large scale energy. One of the primary reasons is its energy density. It typically has a heating value from approximately 150 BTU/ft 3  to 400 BTU/ft 3 . When compared to natural gas, or methane at approximately 1000 BTU/ ft 3  the syngas is typically ⅙ to ⅓ the energy density. It also has varying BTU content and composition in most applications that generate syngas. 
         [0006]    These problems for the most part have relegated syngas to only small scale electrical energy production. In most cases production is below 10 MW. In these small scale electrical energy systems typically one or more internal combustion engines are used to drive electric generators. These systems are somewhat tolerant of low and varying fuel BTU content combined with varying compositions that effect combustion. Even with these positive traits the internal combustion engines must be approximately 3 to 6 times the size, quantity, and cost of a similar generator sets that would be optimized for natural gas, or methane. As is obvious the varying fuel content and BTU level of syngas is also a tremendous reliability and operational problem, independent of the power density. 
         [0007]    When turbines are used the same problems are only magnified. The is unfortunate because a modern combined cycle turbine electric generation system is typically one of the most energy efficient methods of producing electricity from a liquid, or gaseous fuel source known today. 
         [0008]    The present invention teaches a way of solving all of the above problems in an energy efficient, and cost effective way. It is well suited to large scale integration. It also produces a minimal to carbon neutral footprint. 
         [0009]    Two scientists, Drs. Circeo and Camacho, have distinguished themselves as pioneers in the field of employing plasma for energy reclamation purposes, and more specifically, in the use of plasma in a unique application referred to as “in situ.” The concept of these two scientists is described in their U.S. Pat. No. 4,067,390. However, this concept has not enjoyed widespread industrial use for a number of reasons. First, with respect to in situ plasma applications, relatively poor energy density is achieved. Also, the chemical composition of the syngas that is produced from the known in situ application varies. Since the in situ sites are usually remote the energy density problem is accentuated by associated energy transportation issues. 
         [0010]    As a result of the foregoing, syngas has not widely been applied to the production of large scale energy, or chemical feedstock use, particularly because its energy density is low. Typically, syngas has a heating value of approximately between 150 BTU/ft 3  to 400 BTU/ft 3 . When compared to natural gas, or methane at approximately 1000 BTU/ft 3  the syngas is typically ⅙ to ⅓ the energy density. It also has varying BTU content and composition in most applications that generate syngas. 
         [0011]    These problems for the most part have relegated syngas to only small scale electrical energy production. In most cases production is below 10 MW. In these small scale electrical energy systems typically one or more internal combustion engines are used to drive electric generators. These systems are tolerant of low and varying fuel BTU content combined with varying compositions that effect combustion. Even with these positive traits the internal combustion engines must be approximately 3 to 6 times the size, quantity, and cost of a similar generator sets that would be optimized for natural gas or methane. It is also evident that the varying fuel content and BTU level of syngas creates a significant reliability and operational problems, independent of the low power density. 
         [0012]    When turbines are used, the foregoing problems are accentuated. This is unfortunate because a modern combined cycle turbine electric generation system is among the most energy efficient methods of producing electricity from a liquid or gaseous fuel source. 
         [0013]    If the syngas is produced to be used for a feedstock in a chemical process the same issues are also detrimental to its success. When compared to the classic feedstock of natural gas for the chemical industry the parallel of issues is obvious. 
         [0014]    This invention teaches a method of solving all of the above problems in an energy efficient, and cost effective way. It is well suited to large scale integration. It also produces a minimal carbon footprint, or is neutral in that regard. 
       SUMMARY OF THE INVENTION 
       [0015]    The foregoing and other objects are achieved by this invention which provides a method that includes the steps of: 
         [0016]    producing syngas in a syngas generating system that employs a gassifier; 
         [0017]    recovering excess heat from the syngas using a heat recovery arrangement; and 
         [0018]    subjecting at least a portion of the syngas to a reaction in a reactor. 
         [0019]    In an advantageous embodiment of the invention, the reactor is a selectable one of a Fisher Tropsh style reactor, a Richardson reactor, a Sabatier reactor. In other embodiments, the reactor produces fuels, and is a selectable one of a methane reactor arrangement, an ethane reactor arrangement, a propane reactor arrangement, a butane reactor arrangement, a cetane reactor arrangement, and a methanol reactor arrangement. 
         [0020]    In a highly advantageous embodiment of the invention, the gassifier is a plasma gassifier. Also, the heat recovery arrangement is a sensible heat recovery arrangement that issues excess heat as steam. The excess heat is applied to make electricity. 
         [0021]    In a further embodiment, the step of recovering excess heat from the syngas comprises the step of recovering low level sensible heat from the syngas. The excess heat is applied to make electricity. 
         [0022]    The syngas is subjected to the further step, in some embodiments, of being cleaned. 
         [0023]    In other embodiments, there is provided the further step of water gas shifting the syngas to enhance hydrogen production. 
         [0024]    In an advantageous embodiment of the invention, there is provided the further step of operating the gassifier in a selectable one of a pyrolysis mode of operation, a nitrogen reduced mode of operation, an oxygen enriched mode of operation, and a coke supplemented mode of operation. 
         [0025]    A product is produced in accordance with the invention by the further step of conducting the syngas to a reactor to produce a product. The reactor is a selectable one of a pellet style reactor, a monolith style reactor, a foam reactor, a ceramic foam reactor, an alumina oxide reactor, and an alpha alumina oxide reactor. Moreover, the reactor is configured in respective embodiments of the invention to be a selectable one of a Sabatier reactor, a Fisher Tropsh reactor, a Methanol reactor, and a Richardson Reactor. Other steps that are applied in the practice of this method aspect of the invention include: 
         [0026]    water gas shifting the syngas to enhance hydrogen production; and 
         [0027]    conducting a product CO 2  from said step of water gas shifting to a selectable one of an algae bioreactor and a pond. 
         [0028]    In the practice of the invention, there is provided the further step of enhancing a concentration of H 2  by using a selectable one of an aqueous solution, a PSA, and a membrane separation system. In such embodiments, the reactor is configured to be a Methanol reactor, and there is provided the further step of condensing and separating a gaseous methanol from the balance of the syngas product. Subsequently, a reactor product or fuel is conducted into an energy converting system. The energy converting system is, in respective embodiments of the invention, a selectable one of an internal combustion engine generator and a combined cycle electricity generating system. 
         [0029]    In accordance with a further method aspect of the invention, there is provided a method of increasing the BTU content and quality of Syngas. This further method aspect includes the steps of: 
         [0030]    producing syngas in an in situ plasma gassifier operated in a pyrolysis mode; and 
         [0031]    recovering heat from the syngas using a heat recovery arrangement. 
         [0032]    In one embodiment, there is provided the further step of subjecting at least a portion of the syngas to a reaction in a reactor. This includes, in some embodiment, the further step of conducting the syngas to a reactor to produce product. In such embodiments, the reactor is a selectable one of a pellet style reactor, a monolith style reactor, a foam reactor, a ceramic foam reactor, an alumina oxide reactor, and an alpha alumina oxide reactor. 
         [0033]    In embodiments of the invention where the reactor is a Methanol reactor, there is provided the further step of condensing and separating a gaseous methanol from the balance of the syngas product. There are additionally provided the steps of: 
         [0034]    separating CO; and 
         [0035]    reprocessing the separated CO through a water gas shift reactor. 
         [0036]    In one embodiment of this further method aspect of the invention, H 2  is used to make a final product. The final product can, in some embodiment, by methanol. 
         [0037]    In another embodiment of the invention, there is provided the further step of operating the gassifier in a selectable one of a pyrolysis mode of operation, a nitrogen reduced mode of operation, an oxygen enriched mode of operation, and a coke supplemented mode of operation. 
         [0038]    In other embodiments, there is provided the further step of conducting the syngas to a reactor to produce a product. The reactor is a selectable one of a pellet style reactor, a monolith style reactor, a foam reactor, a ceramic foam reactor, an alumina oxide reactor, and an alpha alumina oxide reactor. In still further embodiments, the reactor is configured to be a selectable one of a Sabatier reactor, a Fisher Tropsh reactor, a Methanol reactor, and a Richardson Reactor. There are additionally provided in some embodiments the further steps of: 
         [0039]    water gas shifting the syngas to enhance hydrogen production; and 
         [0040]    conducting a product CO 2  from said step of water gas shifting to a selectable one of an algae bioreactor and a pond. 
         [0041]    In some embodiments, there is provided the further step of enhancing a concentration of H 2  by using a selectable one of an aqueous solution, a PSA, and a membrane separation system. 
         [0042]    In some embodiments the reactor is configured to be a Methanol reactor, and there is provided the further step of condensing and separating a gaseous methanol from the balance of the syngas product. 
         [0043]    The reactor product or fuel is conducted into an energy converting system, the energy converting system being a selectable one of an internal combustion engine generator and a combined cycle electricity generating system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0044]    Comprehension of the invention is facilitated by reading the following detailed description, in conjunction with the annexed drawing, in which: 
           [0045]      FIG. 1  is a simplified schematic representation of a syngas BTU enhancement system constructed in accordance with the invention; and 
           [0046]      FIG. 2  is a simplified schematic representation of an in situ syngas generation system in which the syngas BTU content is enhanced in accordance with the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0047]      FIG. 1  is a simplified schematic representation of a syngas BTU enhancement system  10  constructed in accordance with the invention. As shown in this figure, syngas is produced at a plasma gassifier  100 . In the practice of the invention, gassifier  100  is a conventional gasification system, and in a preferred embodiment of the invention, it is a plasma reactor. The feedstock (not shown) for the syngas is, in some embodiments, a fossil fuel such as coal, or a renewable source of energy such as algae, biomass, or Municipal Solid Waste (MSW). 
         [0048]    Although not specifically shown or designated in the figure, the syngas in various embodiments of the invention can be produced by an oxygen deprived system (pyrolysis), an oxygen enriched system, a nitrogen reduced environment, a coke enhanced system, or any other desired gasification process. 
         [0049]    The syngas available at syngas outlet  101  is, in this embodiment, delivered to a sensible heat recovery system  102 . This heat recovery system is optional, but beneficially serves to make the process energy positive, or at least energy neutral, depending on the gasification method that is implemented. Sensible heat at heat outlet  103  is routed in the form of steam, in this embodiment, to turbine  111  that is in mechanical communication with electrical generator  112 . A low temperature heat recovery system  106  also is optional, and its use in the practice of the invention will depend greatly on the gasification process and feedstock (not shown) that is used. 
         [0050]    The syngas at syngas outlet  107  is then conducted to a cleaning stage  108 , which in this embodiment is a cleaning and polishing module. In respective embodiments of the invention, at least three options are available: 
         [0051]    In a first option, syngas in conduit  114  is, in this embodiment, divided in a flow control valve  129 . Part of the flow is delivered to a water gas shift system  115  to produce additional H 2  at outlet  118 . The resulting CO 2  is, in this embodiment, delivered to an algae bioreactor  120 , which may be a pond, where is converted to O 2  at an outlet  121 , and to biomass at a further outlet  122 . The resulting H 2  boosted syngas then enters a reactor  116 , which in respective embodiments of the invention is a pellet, monolith, foam, ceramic foam, alumina oxide foam, or an alpha alumina oxide foam reactor. In the practice of the invention, reactor  116  is any of a Fisher Tropsh style reactor, a Richardson reactor, a Sabatier reactor, or many other styles of reactor arrangements to produce fuels such as methane, ethane, propane, butane, cetane, methanol, and others. 
         [0052]    In addition to the foregoing, there is provided in accordance with the invention a second option wherein syngas in conduit  114  is, in some embodiments, divided through flow control valve  130  into a Pressure Swing Absorption (PSA) system  123 , which in various embodiments of the invention can be configured as a membrane system, an aqueous solution system, or any other conventional form of H 2  separation system. The separated H 2  is then conducted to reactor  116   a.  The fuel produced at outlet  117   a  of reactor  116   a  is then delivered to electrical power generator  127 , which in this embodiment is an internal combustion power system, or to a combined cycle power generator  128 . It is to be understood that the consistent fuel at outlet  117   a  is not limited to the applications herein mentioned, and can be used for many conventional power conversion systems such as steam boilers, etc. 
         [0053]    As a third option, the syngas in conduit  114  is conducted to a reactor  116   b  that in this embodiment of the invention is configured for the production of methanol. The methanol thereby produced is then conducted to a cooler  126  that condenses out liquid methanol at a methanol outlet  117   b  and expels the balance of the un-reacted CO and syngas byproducts at an outlet  125 . CO product  124  (Option  2 ) and  125  (Option  3 ) can be used as a low BTU fuel, or it can be sold for industrial uses. The CO is, in some embodiments, water gas shifted and reprocessed with the additional H 2  produced through reactor  116  for increased methanol production as seen in sub-loop and reactor  115  which then processes the CO 2  in algae bioreactor  120 . 
         [0054]      FIG. 2  is a simplified schematic representation of an in situ syngas generation system  20  in which the syngas BTU content is enhanced in accordance with the invention. Elements of structure that have previously been discussed are similarly designated. As shown in this figure, syngas is produced by an in situ plasma syngas generator  100 . An illustrative known suitable syngas generator is described in U.S. Pat. No. 4,067,390. However, the present invention is not limited to the in situ system described in that patent. Many new concepts such as tent syngas collection systems, and electronic optical feedback systems will undoubtedly enhance in situ productivity. These improvements are also able to benefit from this invention. Unfortunately no matter how efficiently the in situ syngas is recovered with ever better technical approaches, it still has all the fundamental problems described above once it is recovered. The present invention provides a solution to those problems. 
         [0055]    The syngas produced could be from an oxygen deprived system (pyrolysis), an oxygen enriched system, a nitrogen reduced environment, a coke enhanced system, or any other desired gasification process. Syngas is available at outlet  101  of syngas generator  100  and is then, in this embodiment of the invention, supplied to a sensible heat recovery system  102 . Sensible heat recovery system  102  is not required, but will serve to render the process herein described to be energy positive, or at least energy neutral, depending on the gasification method that is implemented. The sensible heat at sensible heat outlet  103  can, in some embodiments of the invention, be used for power generation or process work, illustratively as described above in relation to  FIG. 1 . The quantity of heat recovered will depend greatly on the gasification process, the energy content of the feedstock, and the depth of the shaft (not shown) from which the energy is recovered. In any case the syngas must be cooled before it is supplied to the next stage. 
         [0056]    As shown in  FIG. 2 , cooled syngas  105  is then supplied to a cleaning and polishing module  108 . Cleaned syngas  114  is then provided to at least three system options, as described above. 
         [0057]    Pursuant to a first option, syngas  114  is divided in a flow control valve  129 . Part of the flow is supplied to water gas shift system  115  to produce additional H 2 . The resulting CO 2    119  is then supplied to an algae bioreactor  120 , which in some embodiments of the invention is a pond, to be converted to O 2    121  and biomass  122 . H 2  boosted syngas  118  then enters reactor  116 . In respective embodiments of the invention, reactor  116  is any of a pellet reactor, a monolith reactor, a foam reactor, a ceramic foam reactor, an alumina oxide foam reactor, and an alpha alumina oxide foam reactor. In other embodiments of the invention, reactor  116  is set up as a Fisher Tropsh style reactor, a Richardson reactor, a Sabatier reactor, or any of several other styles of reactor arrangements that produce fuels, such as methane, ethane, propane, butane, cetane, methanol, and others. 
         [0058]    Pursuant to a second option, syngas  114  is divided through flow control valve  130 , and a portion thereof is supplied to a Pressure Swing Absorption (PSA) system  123 . In various embodiments of the invention, PSA system  123 , is any of a membrane system, an aqueous solution system, and any other conventional form of H2 separation arrangement. The separated H 2  is then supplied to a reactor  116   a , which in some embodiments of the invention, is reactor  116   a.  A fuel  117   a  that is produced by reactor  116  (Option  1 ) or reactor  116   a  (Option  2 ) is supplied to electrical power generator  127 , which is an internal combustion power system, or to combined cycle power generator  128 . It is to be understood that the use of fuel  117   a  is not limited to these applications, and is useful for many conventional power conversion systems (not shown) such as steam boilers, or piped, or trucked off-site in any form such as methanol, or natural gas, to be used in any other industrial, or energy application. A particular advantage of this invention is that fuel  117   a  is at this stage characterized by high energy density, and is an easily transported consistent fuel. 
         [0059]    In some embodiments of the invention, there is available a third option wherein reactor  116   b,  which can also be reactor  116 , is used in combination with a cooler  126  to produce liquid methanol, as herein described. The transportation of this methanol energy source is as simple as transporting gasoline or diesel fuel. 
         [0060]    As noted above, syngas  114  is in some embodiments of the invention supplied to reactor  116   b  (or reactor  116 ), which is configured for the production of methanol. The methanol is then delivered to cooler  126 , which condenses out liquid methanol  117   b  and expels the balance of the un-reacted CO and syngas byproducts at an outlet  125 . CO product  124  (from PSA system  123 ) and CO+ product  125  are useful as a low BTU fuel, and can be sold for industrial uses. In some embodiments, the CO is water gas shifted and reprocessed with the additional H 2  produced through reactor  116   b  for increased methanol production as seen in the sub loop of water gas shift system  115 , which then supplies the CO 2  to bioreactor  120  for processing. 
         [0061]    Although the invention has been described in terms of specific embodiments and applications, persons skilled in the art may, in light of this teaching, generate additional embodiments without exceeding the scope or departing from the spirit of the invention 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.