Abstract:
A solution is provided for CO 2  and other green houses gas reduction at the Coal Fired Power Plants (CFPP). The methods and devices disclosed herein provide an inexpensive source of hydrogen and a hydrogen generating system powered by on-site excess heat generated at the CFPP without producing additional CO 2  emission.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application claims priority under 35 U.S.C. §119(e) of the U.S. Provisional Patent Application Ser. No. 61/610,423, filed Mar. 13, 2012 and titled, “USE ON-SITE EXCESS HEAT TO CONVERT CO2 EMISSIONS INTO HYDROCARBONS INCOME AT COAL-FIRED POWER PLANTS,” which is hereby incorporated by reference in its entirety for all purposes. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to the field of energy conversion. More specifically, the present invention relates to carbon dioxide conversion and usage. 
       BACKGROUND OF THE INVENTION 
       [0003]    Conventional industry produces hydrogen using processes known as Steam Reformation, Partial Oxidation (PDX), and Autothermal Reforming (ATR). These processes use natural gas and steam to produce hydrogen. However, since these processes also create CO x  (x=1, 2), the effectiveness and cleanliness of this hydrogen are questionable because the hydrogen producing systems are also carbon emission/generating sources. 
       SUMMARY OF THE INVENTION 
       [0004]    In some embodiments, the present invention provides a solution for CO 2  and other green house gas reduction at the Coal Fired Power Plants (CFPP). The methods and devices disclosed herein provide an inexpensive source of hydrogen and provide a hydrogen producing system powered by on-site excess heat generated at the CFPP without producing additional CO 2  emission. 
         [0005]    In an aspect, a system for producing a hydrocarbon compound comprising a hydrogen producing unit, a furnace producing heat and carbon dioxide, and a hydrocarbon converter, wherein the hydrocarbon converter receives the carbon dioxide from the furnace and receives hydrogen from the hydrogen producing unit. In some embodiments, the furnace comprises a coal fired power plant. In other embodiments, the furnace comprises a coal-combustor. In some other embodiments, the system further comprises a CO 2 -to-methanol converter. In some embodiments, the hydrocarbon converter comprises a methanol-to-gasoline converter. In other embodiments, the hydrocarbon converter receives hydrogen from the hydrogen producing unit. In some other embodiments, the hydrocarbon converter comprises a Fischer-Tropsch processing unit. In some embodiments, the hydrocarbon converter comprises a paraffin producing unit. In some other embodiments, the hydrocarbon converter comprises a naphtha, kerosene, or diesel producing unit. In some embodiments, the furnace receives oxygen from the hydrogen producing unit. In some embodiments, the hydrogen producing unit generates hydrogen. In other embodiments, the heat generates heated water to be supplied to the hydrogen producing unit. In some other embodiments, the hydrogen producing unit comprises an aluminum compound based catalytic system. In some embodiments, the aluminum compound based catalytic system comprises aluminium compound, copper compound, and silver compound. In other embodiments, the aluminum compound based catalytic system comprises aluminium hydroxide, copper hydroxide, and silver hydroxide. 
         [0006]    In another aspect, a method of producing a hydrocarbon compound comprising generating hydrogen and oxygen using an aluminum based catalyst and heat generated at a power plant and converting CO 2  generated at the power plant to a hydrocarbon compound. In some embodiments, the aluminum based catalyst comprises aluminium hydroxide, copper hydroxide, and silver hydroxide. In other embodiments, the hydrocarbon compound comprises gasoline. In some other embodiments, the hydrocarbon compound comprises paraffin. In some embodiments, the hydrocarbon compound comprises naphtha, kerosene, or diesel. In other embodiments, the hydrocarbon compound comprises methanol. In some other embodiments, the hydrogen and the oxygen are generated at a hydrogen generating chamber. 
         [0007]    In another aspect, a method of mitigating carbon dioxide production comprising generating hydrogen using an aluminium based catalyst at a hydrogen producing unit, combining the hydrogen and substantial all of carbon dioxide generated at a furnace of a power plant, and converting the carbon dioxide to a hydrocarbon compound. In some embodiments, the method further comprises a methanol converter, such that the hydrogen and the carbon dioxide are combined to produce methanol. In other embodiments, the methanol is converted to gasoline at a methanol-to-gasoline converter. In some other embodiments, the methanol-to-gasoline converter receives hydrogen generated at the hydrogen producing unit. In some embodiments, the hydrogen producing unit generates oxygen. In other embodiments, the hydrogen producing unit receives a heated water from a furnace. 
         [0008]    Other features and advantages of the present invention will become apparent after reviewing the detailed description of the embodiments set forth below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Embodiments will now be described by way of examples, with reference to the accompanying drawings which are meant to be exemplary and not limiting. For all figures mentioned herein, like numbered elements refer to like elements throughout. 
           [0010]      FIG. 1  illustrates a coal fired power plant for converting carbon dioxide to gasoline in accordance with some embodiments of the present invention. 
           [0011]      FIG. 2  illustrates a coal combustor plant for converting carbon dioxide to gasoline in accordance with some embodiments of the present invention. 
           [0012]      FIG. 3  illustrates a coal fired power plant for converting carbon dioxide to paraffin in accordance with some embodiments of the present invention. 
           [0013]      FIG. 4  is a flow chart illustrating a method of generating hydrocarbon compounds using waste heat. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0014]    Reference will now be made in detail to the embodiments of the method and apparatus of the invention, examples of which are illustrated in the accompanying drawings. While the invention is described in conjunction with the embodiments below, it is understood that they are not intended to limit the invention to these embodiments and examples. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which are included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to more fully illustrate the present invention. However, it is apparent to one of ordinary skill in the art having the benefit of this disclosure that the present invention is able to be practiced without these specific details. In other instances, well-known methods and procedures, components and processes have not been described in detail so as not to unnecessarily obscure aspects of the present invention. It is, of course, appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer&#39;s specific goals, such as compliance with application and business related constraints, and that these specific goals are vary from one implementation to another and from one developer to another. Moreover, it is appreciated that such a development effort can be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art having the benefit of this disclosure. 
         [0015]    About two thirds of the coal energy consumed at the CFPP is lost to the environment in the form of heat. The present invention provides methods and devices to utilize this wasted energy and convert unwanted carbon dioxide to hydrocarbon commodities with a modest capital expense in added Carbon Capture and Utilization (CCU) infrastructure. The hydrocarbon commodities include methanol, ethanol, gasoline, and diesel. The present invention uses waste heat from the CFPP to generate hydrogen and oxygen, which are used to generate hydrocarbons. 
         [0016]      FIG. 1  illustrates a coal fired power plant  100  for converting carbon dioxide to gasoline in accordance with some embodiments of the present invention. The plant  100  comprises a hydrogen production unit  102 , a methanol-to-gasoline converter (MTG converter)  104 , a CO 2 -to-methanol converter  106 , and a furnace  108 . The furnace  108  is able to be a CFPP, which comprises a coal furnace  108 A, a chamber area for flue gas  108 B, and turbine and condenser  108 C for generating electricity. The hydrogen production unit  102  receives water from the water feedstock  110  and generate hydrogen and oxygen via catalytic reactions in the hydrogen production unit  102 . The reactants, reaction conditions, and the catalysts for the catalytic reactions are described below. Hydrogen  103  that is generated at the hydrogen generation unit  102  is supplied to the CO 2 -to-methanol converter  106  and the MTG converter  104 . Oxygen  112  that is generated at the hydrogen generation unit  102  is supplied to the furnace  108  and the MTG converter  104 . The oxygen  112  that is provided to the furnace  108  facilitates the full oxygenation of COx, which is subsequently supplied to the CO 2 -to-methanol converter  106  via a CO 2  scrubber  114  as a CO 2  source. The CO 2 -to-methanol converter  106  generate about 10% of ethane  116  to be used at the furnace  108  and about 90% of methanol  118  that is supplied to the MTG  104 . Hot water  120  from the furnace  108  is supplied to the hydrogen production unit  102  as a heat source. By using the waste heat from the furnace  108  as an energy source to produce hydrogen and oxygen at the hydrogen production unit  102 , significant amount of energy is able to be saved. The hot water  120  that is used to heat up the hydrogen production unit  102  becomes cold water  122  and  124 , which are used to cool the heat exchanger  126  at the furnace  108 . 
         [0017]    At the MTG  104 , a ZSM-5 zeolite is used to convert methanol, hydrogen, and oxygen to become gasoline. In some embodiments, the methanol-to-gasoline process is able to be a typical methanol-to-gasoline process, such as Mobil® methanol-to-gasoline process. Similarly at the CO 2 -to-methanol converter  106 , typical carbon dioxide to methanol conversion methods are able to be used, such as Haldor-Topsoe. 
         [0018]      FIG. 2  illustrates a coal combustor plant  200  for converting carbon dioxide to gasoline in accordance with some embodiments of the present invention. The coal combustor plant  200  comprises a hydrogen production unit  202 , a methanol-to-gasoline converter (MTG converter)  204 , a CO 2 -to-methanol converter  206 , and a furnace  208 . The furnace  208  is able to be a coal-combustor-to-gasoline (CCTG) system, which comprises a coal furnace  208 A and a flue gas chamber  208 B. In some embodiments, no electricity is produced at the plant  200  but the plant  200  is able to be operated as a high efficiency GTL (gas-to-liquid) plant utilizing more than 80% of the heat generated to produce liquid fuels. The hydrogen production unit  202  receives water from the water feedstock  210  and generates hydrogen and oxygen via catalytic reactions in the hydrogen production unit  202 . The reactants, reaction conditions, and the catalysts for the catalytic reactions are described below. Hydrogen  203  generated at the hydrogen generation unit  202  is supplied to the CO 2 -to-methanol converter  206  and the MTG converter  204 . Oxygen  212  that is generated at the hydrogen generation unit  202  is supplied to the furnace  208  and the MTG converter  204 . The oxygen  212  that is provided to the furnace  208  facilitates the full oxygenation of COx, which is subsequently supplied to the CO 2 -to-methanol converter  206  via a CO 2  scrubber  214  as a CO 2  source. SO 2  and NO 2  from the furnace  208  are supplied to a NO 2  and SO 2  converter  228  via a NO 2  and SO 2  scrubber  215 . The NO 2  and SO 2  is able to be further converted into H 2 SO 4  and N 2  at the NO 2  and SO 2  converter  228 . The CO 2 -to-methanol converter  106  generates about 10%-30% of ethane  216  that is used at the furnace  208  and about 70%-90% of methanol  218  that is supplied to the MTG  204 . Hot water  220  from the furnace  208  is supplied to the hydrogen production unit  202  as a heat source. By using the waste heat from the furnace  208  as an energy source to produce hydrogen and oxygen at the hydrogen production unit  202 , significant amount of energy is able to be saved. The hot water  220  that is used to heat up the hydrogen production unit  202  becomes cold water  222  and  224 , which are used to cool the heat exchanger  226  at the furnace  208 . 
         [0019]      FIG. 3  illustrates a coal fired power plant  300  for converting carbon dioxide to paraffin in accordance with some embodiments of the present invention. The plant  300  comprises a hydrogen production unit  302 , a Fischer-Tropsch chamber  304 , a CO 2 -to-methanol converter  306 , a hydro-treating chamber  310 , and a furnace  308 . The furnace  308  is able to be a CFPP, which comprises a coal furnace  308 A, a chamber area for flue gas  308 B, and turbine and condenser  308 C for generating electricity. The hydrogen production unit  302  receives water from the water feedstock  314  and generates hydrogen and oxygen via catalytic reactions in the hydrogen production unit  302 . The reactants, reaction conditions, and the catalysts for the catalytic reactions are described below. Hydrogen  303  that is generated at the hydrogen generation unit  302  is supplied to the CO 2 -to-methanol converter  306  and the Fischer-Tropsch chamber  304 . Oxygen  313  that is generated at the hydrogen generation unit  302  is supplied to the furnace  308 . The oxygen  313  that is provided to the furnace  308  to facilitate the full oxygenation of COx, which is subsequently supplied to the CO 2 -to-methanol converter  306  via a CO 2  scrubber  312  as a CO 2  source. The CO 2 -to-methanol converter  306  generates about 30% of methane  320  to be used at the furnace  308 . Hot water  316  from the furnace  308  is supplied to the hydrogen production unit  302  as a heat source. By using the waste heat from the furnace  308  as an energy source to produce hydrogen and oxygen at the hydrogen production unit  302 , a significant amount of energy is able to be saved. The hot water  316  that is used to heat up the hydrogen production unit  102  becomes cold water  318 , which is used to cool the heat exchanger  326  at the furnace  308 . At the Fischer-Tropsch chamber  304 , paraffin that is produced is sent to the hydro-treating chamber  310 , such that the paraffin is able to be converted to naphtha, kerosene and diesel. 
         [0020]      FIG. 4  is a flow chart illustrating a method  400  of generating hydrocarbon compounds using waste heat. The method  400  is able to begin at Step  402 . At Step  404 , a hydrogen producing unit is prepared. The hydrogen producing unit contains an aluminum based catalytic system, which is described below. At Step  406 , hydrogen and oxygen are produced using waste heat that is generated at a furnace. In some embodiments, the furnace comprises a Coal Fired Power Plant (CFPP), A Coal-Combustor-to-Gasoline (CCTG) Plant, or a methanol producing plant. A person of ordinary skill in the art will appreciate that any plant that generates excess heat is within the scope of the present invention, such as a nuclear power plant. At Step  408 , hydrogen and oxygen produced with carbon dioxide are supplied to a hydrocarbon converter. At Step  410 , carbon dioxide is converted to hydrocarbon compounds. The method stops at Step  412 . 
         [0021]    In the following, catalysts that are used in the hydrogen producing unit, such as the hydrogen production unit  102 ,  202 , and  302  at  FIGS. 1-3 , are described in accordance with some embodiments of the present invention. 
       Example 1 
       [0022]    The apparatus includes a main reactor, a photochemical/oxidizer reactor, and a thermal converter. The main reactor contains graphite and stainless steel parallel plates as electrodes, reactants, or catalysts. The photochemical/oxidizer reactor contains a light source, such as light, sunlight receiver, solar water heater, or other proper lights or heaters. 
         [0023]    The conditions and procedures of performing the reactions are described in detail below. The experiment begins from catalyst preparation. In the catalyst preparation procedure, water, salts, and the starting metals including substrates of Al, Cu, and Ag are placed into a catalyst preparation vessel. Next, the starting materials are prepared by using the REDOX reaction, which is described in the following paragraph. Subsequently, the product of the catalysts preparation reaction is transferred to the main reactor. The main reactor comprises water, which is able to be prepared from tap water, distilled water, deionized water, or sea water. The salts are added to bring the salinity to 1.5% by weight using NaCl. 
         [0024]    In the REDOX reactions, an electrical voltage is applied to the electrodes. The negative charge is connected to graphite electrodes and positive charge is connected to copper, silver, and aluminum substrates. The reactions are started by applying 1.6 volts of electricity or to the point where the Al substrate begins to liberate gas. The reactions are running for 30-40 minutes or until a clear gel suspension or heavy, white, frothy supernatant is developed. The solution is stirred occasionally until the supernatant completely dissolves into solution and forms a gelatinous suspension. 
         [0025]    Following the catalysts preparation is the pre-generation reaction. In the pre-generation reaction, the anode in the main reactor (the stainless steel electrode) is conditioned. In some embodiments, the temperature of the reaction is set in the range from 80° F. to 130° F. The negative charge of applied electricity is connected to the stainless steel electrode and the positive charge is connected to the graphite electrode. Before applying electric voltage, the Cu, Al, and Ag metals are taken out of the solution. Next, 0.5 Volts of electricity is applied. After the current is stabilized, then voltage is added in the increments of 0.1 volts until the voltage is roughly 0.7 volts or until H 2  gas is produced at the stainless steel substrate. In some embodiments, it is observed that the pH value of the solution increases quickly during the pre-generation reaction. Following the pre-generation reaction, the generation reaction is performed. In the generation reactions, the voltage is increased by 0.05 volt increments, such as 0.805V, 0.810V, and 0.815V. The voltage is continuously added to roughly 0.825 volts or until the maximum amount of the gas is generated. During this phase, hydrogen gas is produced at the stainless steel substrate. Then the voltage is reduced by 0.05 volts to find where the gas production falls off. 
         [0026]    The hydrogen gas in the above setup is produced from the stainless steel electrode. It is observed that during the reaction, the pH value slowly increases. After the reaction, the pH of the solution decreases to about 6.5. 
         [0027]    In some embodiments, the reaction begins with 0.22 g of Al, 0.11 g of copper and 0.17 g of silver metals, and five liters of gas is produced by using this renewable catalytic system. A person of ordinary skill in the art appreciates that an equal ratio/similar ratio scaling up to any level, such as for pilot plant or full industrial production plant, is within the scope of the present invention. 
         [0028]    After the above reactions, the hydrogen generating substance is depleted, so the solution in the main reactor contains the depleted hydrogen generating substance and hydroxides bonded hydroxide shuttles. The solution is transferred from the main reactor to the oxidizer reactor for oxygen reaction to revive the hydroxide bonded hydroxide shuttles and hydrogen generating substance. The oxidizer reactor takes the frothy white supernatant from the main reactor and converts it to a gelatinous suspension. The gelatinous suspension contains the reactivated hydrogen generating substance, and the solution containing the gelatinous suspension is then transferred back to the main reactor. The oxidizer reactor is able to be a heat exchanger, photochemical reactor, or the thermal converter. The oxidizer reactor goes on when the pH value of the reacting solution goes up. 
       Example 2 
       [0029]    The apparatus comprises a preparation reactor, a main reactor, a photochemical/oxidizer reactor, and a thermal converter. The reaction begins from preparing a solution containing Al metal 250 mg, Cu metal 250 mg, Ag metal 250 mg, a graphite electrode and 1 liter of water having 1.5% NaCl 510 by weight. A negative voltage −2.5V is applied to the graphite electrode and a first positive voltage 1.7V is applied to the Al metal for 15 minutes. Next, the first positive voltage that is applied to the Al metal is stopped, and a second positive voltage 1.4V is applied to the Cu metal for 10 minutes while the negative voltage −2.5V is concurrently applied to the graphite electrode. Next, the second positive voltage to the Cu metal is stopped, and a third positive voltage 1.0V is applied to the Ag metal for 5 minutes with the negative voltage still applied to the graphite electrode. The temperature of the solution is maintained at 88° F. In some embodiments, the procedures that are described above include the procedures of ionizing the metals into the solution. In some embodiments, the procedures are catalysts preparation. 
         [0030]    Next, the solution is transferred into a main reaction vessel. The main reaction vessel comprises aluminium compound, copper compound, silver compound, sodium compound, and chloride compound. The term “compound” comprises all ligand states of the metal. For example, the aluminium compound include Al 3+ or Al(OH)   x , where the x represents the coordinated ligand numbers of the aluminium ion. In some embodiments, a voltage between 0.4V to 0.9V is applied to the cathode of the electrodes. In alternative embodiments, a voltage 0.85V is applied to the cathode of the electrodes. In other embodiments, a voltage not exceeding 0.9V is applied to the cathode of the electrodes, because it is found that hydrogen production is reduced in some experiments when a voltage exceeding 0.9V is applied. In some embodiments, the applied voltage of the anode is at 0V compared with the standard hydrogen electrode. In alternative embodiments, the anode of the electrodes is the reference electrode, which has a 0V. In some embodiments, the voltage is applied in a way that a negative charge is applied on the stainless electrode and a positive charge is applied at the graphite electrode. An electric hydrolysis reaction begins to occur when sufficient voltage is applied, and hydrogen gas is generated at the stainless electrode when the applied voltage is applied on the stainless electrode and the graphite electrode. After 30 minutes or when the amount of hydrogen gas production begins to decrease, the solution is transferred through the heater and passing through the LED lights for a photolysis reaction. Oxygen gas is collected at the outlet during the photolysis reaction. The solution is transferred back to the main reaction vessel for hydrogen production. 
         [0031]    In some embodiments, a controlling system is connected to all components of the setup, including the catalysts preparation vessel, the main reaction vessel, the valves, the heater, the LED lights, and all electrodes. In some embodiments, the controlling system comprises computers, which are able to automate the control of each of the components of the setup. Accordingly, the controlling system is able to automate the whole electric hydrolysis process when predetermined conditions have been attended. For example, the controlling system is able to automatically initiate the reaction by applying a voltage to the preparation vessel at a trigger of a predetermined condition when hydrogen gas is needed. The controlling system is able to automatically stop the ionization process of the metals when a pre-set condition has been reached. For example, a pre-set pH value or applied voltage. Similarly, the controlling system is able to automatically transfer the solution among the various chambers or vessels by controlling the pump and the valves. 
         [0032]    By having the controlling system, the setup is able to be controlled remotely. For example, the setup is able to be controlled by a website, through internet, telephone, or PDA. In some embodiments, the processes of the setup can be all automated at the occurring of the predetermined conditions, such as a preset timer. 
         [0033]    Above are some embodiments of the catalytic hydrogen/oxygen producing systems of the present invention. U.S. patent application Ser. No. 12/706,639, filed Feb. 16, 2010, and entitled “Method and Apparatus for Efficient On-demand Production of H 2  And O 2  From Water Using Waste Heat and Environmentally Safe Metals”, which claims priority from U.S. Provisional Patent Application Ser. No. 61/154,282, filed Feb. 20, 2009 and entitled “Method and Apparatus for Efficient On-demand Production of H 2  And O 2  From Water Using Environmentally Safe Metals”, which are all hereby incorporated herein by reference in their entirety for all purposes. Further, U.S. patent application Ser. No. 13/366,216, filed Feb. 3, 2012 and entitled “Stability Control of a Hydrogen Generating System and Method,” which is hereby incorporated herein by reference in its entirety for all purposes. 
         [0034]    To utilize the on-site excess heat at a power plant, the excess heat heats up water to be transported to the hydrogen producing unit as an energy source to increase a hydrogen and oxygen producing rate. 
         [0035]    In operation, the hydrogen production unit produces hydrogen and oxygen, which are supplied to CO 2 -to-methanol converter, the methanol-to-gasoline converter, and/or the hydrocarbon compound converter, such that carbon dioxide are able to be converted to hydrocarbons. 
         [0036]    The present invention has been described in terms of specific embodiments incorporating details to facilitate the understanding of principles of construction and operation of the invention. Such reference herein to specific embodiments and details thereof is not intended to limit the scope of the claims appended hereto. It will be readily apparent to one skilled in the art that other various modifications may be made in the embodiment chosen for illustration without departing from the spirit and scope of the invention as defined by the claims.