METHOD FOR THE PRODUCTION OF HYDROGEN AND APPLICATIONS OF THE SAME
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for the production of hydrogen gas. More particularly, the present invention relates to a method for the production of hydrogen gas by vapor reduction wherein the vapqr contacts the fused metal to form a metal oxide and a gas stream containing hydrogen. The metal oxide can thus be reduced back to the metal for more production of hydrogen gas. Hydrogen gas can be used for the generation of errigy and in various chemical processes, such as the treatment of coal and the production of ammonium.
2. Description of the Related Art Hydrogen (H2) is a special and practical valuable chemical that is critical for a number of industrial processes including ammonium and oil refining. In addition, hydrogen can be converted directly into electricity in energy cells in coefficients that approach 80 percent. Water is a unique derivative of the conversion of hydrogen n energetic cells, and toxic emissions are eliminated. For these reasons, hydrogen is widely considered the fuel of the future. It is known that hydrogen gas can be produced from various different feed tanks such as natural gas, bipumase or water using different techniques such as reforming, gasification or electrolysis. The most common methods are steam methane reformation (RMV), carbon gasification, steam reduction, biomass gasification and pyrolysis, and electrolysis. It is believed that steam methane formation is the commercially viable and most economical process currently available. In the RMV process, methane (CH4) reacts with steam (H2O) to form a gas stream that includes hydrogen and carbon monoxide (CO). The feed tank is typically natural gas and the cost of natural gas represents a significant part of the total production cost. At least two main difficulties are associated with the RMV method. One difficulty is the dependence on the cost of hydrogen production on the natural gas price. The price of natural gas is highly volatile due to the supply / demand interests, which are projected to persist in the future. Secondly, the hydrogen produced by RMV is co-mixed with a significant amount of carbon oxides that can only be removed, partially by washing or oscillating absorption under pressure, both are costly, the carbon oxides that remain in the RMV hydrogen they are harmful to the catalysts used in energy cells and in the production of ammonium (NH3) from hydrogenated. The production of hydrogen for coffee processing is another established commercial technology, but only economically competitive when natural gas is expensive to a prohibitive degree. In the gasification process of. carbon, oxygen (02) and carbon are used in the coal gasifier to produce a hydrogen-containing gas, and hydrogen of high purity can be extracted from the synthesis gas by a water-gas exchange reaction followed by the removal of the dioxide. of carbon (C02) by washing or oscillating absorption of resistance. Impurities, such as acid gases, must also be separated from hydrogen. Hydrogen can also be formed by the gasification of other hydrocarbons such as residual oil. The vapor reduction method uses the oxidation of a metal to distill the vapor oxygen (i.e., vapor reduction), thereby forming the hydrogen gas. This reaction is illustrated by Equation 1. xMe + yH20? exOy + yH2 (1) To complete the cycle in a two-stage vapor reduction process, the metal oxide must be reduced back to the metal using a reducing agent. For example, carbon monoxide (CO) has an oxygen affinity that is similar to the oxygen affinity of hydrogen and are equal at about 812 ° C. At temperatures above approximately 812 ° C, CO has a higher affinity for oxygen than hydrogen has. Thus, if the CO has an oxygen affinity greater than the oxygen affinity of the metal in equilibrium, the CO will reduce the oxide of Equation 1 back to the metal. MexOy + yCO? xMe + yC02 (2) Generally established, the function of metal / metal oxide torque is to transfer the oxygen from the vapor to the reducing gas (CO) without allowing the hydrogen / hydrogen from the hydrogen production stage to contact the carbon monoxide / carbon dioxide of the metal oxide reduction stage. Metal and metal oxide are not consumed by the overall process. The oxygen partial pressure (p02) refers to the ease with which the metal can be oxidized (for example, by steam) and the oxide can be reduced (for example, by CO). A related mathematical expression is pH20 / pH2l which is proportional to the partial pressure of oxygen. Also, an equivalent and inversely related quantity is the hydrogen fraction, expressed as: pH2 (3) (pH2 + pH20) Certain metals react strongly with water, releasing hydrogen. Examples of such metals include: lithium (Li), sodium (Na), potassium (K), rubidip (b), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca) ), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al), silicon (30, phosphorus (P), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn) , yttrium (Y), zirconium (Zr), niobium (Nb), lanthanum (La), hafnium (Hf), tantalum (Ta) and gallium (Ga) The partial pressure of oxygen in equilibrium with these metals and their oxides together It is extremely low: once the oxides are formed, they can not be effectively reduced back to the metal by carbon monoxide, Conversely, there is another group of metals that produce insignificant amounts of hydrogen when they react with water. include: nickel (Ni), copper (Cu), ruthenium (Ru), rhodium (Rh), palladium (Pd), plate (Ag), cadmium (Cd), rhenium (Re), osmium (Os), iridium (Ir ), platinum (Pt), ord (Au), mercury (Hg), lead (Pb), bismuth (Bi), selenium (Se) and tellurium ( Te). The partial pressure of oxygen in 99%? these metals and their oxides together is completely high. Therefore * the oxides can be easily reduced by carbon monoxide. Between the two preceding groups of metals are other metals characterized by an oxygen affinity which is strictly the same as the affinity of hydrogen qxygenation. In this intermediate group of metals $ e are included: germarium (Ge), iron (Fe), zinc (Zn), tungsten (W), molybdenum (Mo), indip (in), tin (Sn >);, cobalt (Co) and antimony (Sb). These are elements that easily produce hydrogen vapor where the resulting oxide can be reduced by carbon monoxide. That is to say, these metals have an affinity of pxi &ene in such a way that their equilibrium pH20 pH2 is sufficiently low to be practical for the production of hydrogen, still the metallic oxide is easily reduced by carbano to normal pyrometallurgical temperatures (for example , approximately 1200 ° C). These metals are referred to herein as reactive metals, it being understood that both the metal can be oxidized by vapor and the metal oxide can be reduced by carbon monoxide. The oxidation process of steam reduction / iron oxidation was the main industrial method for making hydrogen during the 19th and early 20th centuries. At elevated temperatures, iron distills the oxygen from the water, leaving pure hydrogen.
3Fe + 4H20? Fe304 + 4H2 (4) Excess water is required to maximize hydrogenation of a given amount of iron. After the hydrogen is produced, the excess water is condensed leaving a vapor of uncontaminated hydrogen gas. The reaction products of the steam reduction / iron oxidation process are pure hydrogen and zinc sulphide (FeO) and / or magnetite (Fe304). To regenerate the metal, the carbon monoxide carbon captures the oxygen of the iron oxide, forming iron metal and carbon monoxide or carbon dioxide (O2). In the early years of hydrogen production, these two stages were taken to different locations. The main cost components for producing hydrogen by this method included the cost of the iron used minus the value received for the iron oxide produced and the production cost of the excess steam required to drive the reaction (a function of temperature). This cost was reduced by the benefits derived from recovering the excess steam energy. There are numerous examples in the prior art of the preceding method. The U.S. Patent No. 1, 345,905 by Abbott describes the production of steam hydrogen iron oxidation using multiple reactors. In a configuration of four reactors, one reactor is used for iron oxidation (hydrogen production), two are used for the reduction of iron oxide and the fourth is used to preheat the reactors. The gas flows can be switched between the reactors for the continuous production of hydrogen.
U.S. Patent No. 4,343,624 by Belke et al., Discloses a 3-step hydrogen production method and apparatus utilizing vapor reduction as the hydrogen source. In a first step, a low BTU gas containing hydrogen and carbon monoxide is formed from a feed tank such as coal. The steam and iron react) so in a third stage to form hydrogen gas and magnetite. It is disclosed that the magnetite can be returned to the second stage for use in the reduction reaction, such as by continuously returning the magnetite to the second stage reactor by means of an impedance conduit. At least one of the steps takes place in a rotary fluidized bed reactor. The U.S. Patent No. 4,555,249 by Leas describes a unit that fractionates the gas containing a reactive powder, such as a mixture of iron, having a significant weight difference between the reduced form and the oxidized form. The unit includes two parg zones containing the reactive powder, an oxidation zone and a reduction zone, where the hydrogen gas is extracted from the oxidation zone. As the reactive powder is converted from the oxidized to the reduced form, the weight of the powder increases and the change in weight is used to transfer the reduced powder into the oxidation zone while moving the oxidized powder to the reduction zone. . The article "H2 from BioSyngasia Iron Reduction and Oxidation", by Straus et al. , describes a method for the production of hydrogen from biosingas. The biosingas, that includes H2, CO, H2Q, and C02 with indications of N2 and CH4 is used to reduce the magnetite to iron. The iron is cooled like this and fed to a hydrogen gas generator where the iron is contacted with the vapor to form the hydrogen by steam reduction. The iron oxide is cooled in this way and returned to the metal oxide reduction reactor for reaction with biosipgas. The disadvantages give | Steam reduction process using iron include that the reaction of solid iron with steam produces an oxide cap, which inhibits the additional vapor from reacting with iron below the oxide layer and therefore the reaction rate is limited by the speed of gas diffusion through the oxide layer. Also, the reaction rate is dependent on the surface area of the iron available for the reaction. Nevertheless, the high surface area, is equated with small particle size, and small particles are expensive to process. In addition, there are difficulties associated with the reduction of iron oxide. A method for reducing iron oxide includes the melting of the oxide and therefore carries the disadvantage of high temperature due to the high melting point of iron (1538 ° C). In another method, the iron oxide is reduced to the metal in the solid state by carbon and / or reducing gas. However, this last process is inefficient and kinetically difficult. Excluding the reduction in the solid state, for each ton of hydrogen produced, a minimum of 20.8 tons of iron and 28.7 tons of magnetite must be physically moved from one reactor (metal oxidation) to another (metal reduction). Other metals besides iron have been used for vapor reduction processes. The U.S. Patent No. 1, 050,902 by Acker describes the use of tin or zinc in a vapor reduction process to form hydrogen and the regeneration of the metal by reduction of the metal oxide with carbon. The U.S. Patent No, 3,821, 362 by Spacil illustrates the use of Sn / Sn02 to form hydrogen. The molten flaw is atomized and contacted with steam to form Sn02 and hydrogen gas. The Sn02 is thus contacted with a producing gas produced from H2, N2 and CO, which is formed by contacting the powdered coal with air. Sh02 is reduced to liquid tin, which is transferred back to the first reactor. Urt similar method for the production of hydrogen is illustrated in the patent of E-U- No. 3,979,505 by Seitzer. The Patents of E.U. Nos. 4,310,503 and 4,216,199 by Erickson describe a comprehensive investigation of the potential of tin to act as the vehicle of oxygen from steam to carbon dioxide. An extension of this work is also reported in "Hydrogen from Coal via Tin Redox" by Erickson, prepared by the Office of Inventions Related to Energy, Department of E.U. of Energy (February 1981). Erickson reports that hydrogen production obtainable from a given amount of carbonaceous reducing composition can be increased by using a multi-stage process where the successive stages are adjusted in order to increase pH2 / pH20 in equilibrium for the oxidation reaction of metal put steam . Among the substances used as intermediates (ie, metal / metal oxide motors), pure solids such as iron, zinc sulfate (FeO), tungsten dioxide such as tin and indium were found; and liquid liquids such as tin, indium, gemanium, zinc, and iron, where dissolved means that the intermediate occurs less than the unit activity. The effect of using a dissolved liquid is that the oxygen partial pressure is mined (ie, the hydrogen fraction becomes red) and less hydrogen is produced. Erickson describes that suitable solvents for liquid djsueltós be selected from one or more non-reactive metals having a high oxygen partial pressure, for example, copper, lead and -híquel. It is also described that tin, a reactive metal, can serve as a solvent for indium. When hydrogen is formed by using tin in a vapor reduction process, the first reaction is: Sn + 2H20 - * · SnO? + 2H2Ó (5) To ensure reasonable kinetics for the above reaction, a temperature of approximately 900 ° C is required, and tin is a liquid at that temperature (Tm-232 ° C). At such temperatures, thermodynamics dictates that a large excess of steam is required in order for the reaction to proceed. The need for a large excess of steam creates a number of problems. The heat must be recovered for the process to be economical, including the evaporation of the water to form the steam. Technically, most of this heat recovery is possible, although doing so requires additional capital. Also, a large excess of steam must physically contact the tin, such as by bubbling through the liquid tin. Practically, such a procedure is possible only if the steam and the reactor are operated under considerable pressure and, generally, the manufacturers operating at very high pressures are completely expensive. For example, the production of one ton of hydrogen requires the reaction of &.94 tons of steam with 29.4 tons of tin (stoichiometric calculations). Addition- ally, the production of one ton of hydrogen at 900 ° C requires 35.7 tons of steam to satisfy the thermodynamic requirement. If this requirement total steam (44.6 tons) passes through the stoichiometric amount of tin at atmospheric pressure, the vapor velocity through space that could otherwise be occupied by the tin must be in I exceed 100 meters per second. This produces a nominal residence time of less than 1/100 of a second. Even if the system pressure rises to 100 atmospheres, only 0.85 seconds are available for the reaction to approach equilibrium. A quantity of tin in excess of the stoichiometric requirement can be used, and the effect of a higher weight (larger volume) of tin is to increase the nominal residence time. However, this method of increasing the nominal residence time is expensive, due to the increased size of the tin-vapor reactor and increased inventory of tin required. In this way, the need remains for a method to produce hydrogen that is technically productive and economically viable. Both steam / tin and steam / iron processes are technically feasible. However, none of them met the economic viability requirement. The steam / iron process is not satisfactory because: (1) the production of hydrogen is controlled diffusion; (2) the cost of moving the metal is high; and (3) the difficulty (cost) of reducing iron is high. Steam / tin processing fails the economic viability requirement due to low kinetics at low temperatures (below about 800 ° C) and poor thermodynamics at higher temperatures. The consequence of thermodynamics little is the requirement that large quantities are processed through the fused metal, which increases impaired and the cost of the process, because of these and other factors, the present inventors are not aware of a commercial facility that is practice the method of steam reduction, instead of the high demand for hydrogen gas.
BRIEF DESCRIPTION OF THE INVENTION According to one embodiment of the present invention, a method is provided for the production of a gas stream containing hydrogen. The method includes the steps of generating steam and contacting the vapor with a mixture of fused metal having at most about 20 weight percent dissolved iron in a metal diluent, wherein at least a part of the iron is oxidized into a metal oxide. and at least a part of the vapor is reduced to form a gas stream containing hydrogen. Preferably, the metal diluent is tin. By contacting the vapor with the iron that dissolves in μ? metal diluent, the problems associated with the kinetic and thermodynamic limitations inherent in the previous vapor reduction methods are reduced. According to another embodiment, there is provided a method for the production of a hydrogen-containing gas wherein the steam is generated and contacted with a mixture of metal fused at a temperature of at least about 100 ° C. The fused metal mixture includes a reactive metal dissolved in a metal diluent wherein the reactive metal is oxidized and the vapor is reduced to form hydrogen. The use of temperatures of at least about 100 ° C for the mixture of fused metal allows the production of hydrogen to drop favorable kinetic and thermodynamic conditions. according to another embodiment, a method is provided for the production of a gas stream containing hydrogen which includes the steps of generating steam, contacting the vapor with a mixture of metal fused in a reactor, wherein the particles containing Reactive metal is dispersed in the fused metal mixture. The particles containing reactive metal visually provide additional reactive metal to the fused metal mixture as the reactive metal is oxidized by the vapor. According to another embodiment, there is provided a method for the production of a gas stream containing hydrogen which includes the steps of contacting the vapor with a mixture of metal fused in a reactor, the mixture of fused metal including a reactive metal dissolved in a metal diluent. The reactive metal is oxidized in a metal oxide by the vapor. The metal oxide is thus reduced back to the reactive metal inside the reactor. The hydrogen-containing gas stream produced according to the foregoing can be used in a variety of processes and is particularly suited to the treatment of carbon-producing substances such as coal or waste and the processing of chemicals such as amphene.
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a binary phase diagram for a tin-iron metal mixture that is useful in accordance with the present invention. Figure 2 illustrates the rate of hydrogen production as a function of iron content in the reactor according to one embodiment of the present invention. Figure 3 illustrates the rate of hydrogen production as a function of iron content and reaction temperature according to one embodiment of the present invention. Figure 4 illustrates a reactor operating in reactor reduction mode according to an embodiment of the present invention. Figure 5 illustrates a reactor that operates in a metal oxide reduction mode according to one embodiment of the present invention. Figure 6 illustrates a process flow for the production of continuous hydrogen according to the present invention. Figure 7 illustrates a process flow for the treatment of coal or other organic containing feedstock according to the present invention. Figure 8 illustrates a process flow for ammonium production according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION According to the present invention, the hydrogen gas (H2) is formed by contacting the steam 4H2Q) with a fused metal mixture including at least a first reactive metal that dissolves at least partially at least? ?? metal diluent. The metal diluent can also be reacted with steamIt is, by definition, less reactive with the vapor than with the reactive metal. In this manner, the oxygen in the vapor preferably reacts with the reactive metal to oxidize the reactive metal to a metal oxide and reduce a portion of the vapor to form a stream of hydrogen-containing gas that will also include excess vapor. In a preferred embodiment, the production of hydrogen continues until the concentration of the reactive metal dissolved in the molten metal mixture is reduced to a minimum concentration dictated by economy, at which point the steam injection is terminated. Thus, a reducing agent is introduced into the reactor under conditions of intense mixing, such as by using a spear submerged in the upper part. Under these conditions, the metal oxide is chemically reduced back to the reactive metal, which is re-dissolved in the fused metal mixture. By changing the flow of steam and reducing agent between two or more reactors, hydrogen can be produced substantially continuously. The method of the present invention provides significant advantages! on the steam reduction methods of the prior art. To start the production of hydrogen, the steam is contacted with a mixture of fused metal including at least one third reactive metal and at least one first diluting metal. Reactive metal is, by definition, more reactive with steam than dilute metal. The reactive metal preferably has an oxygenate affinity that is similar to the oxygen affinity of hydrogen and reacts with the vapor to form a metal oxide. For example, the reactive metal can be selected from germanium (Ge), iron (Fe), zinc (Zn), tungsten (W), molybdenum (Mo), indium (In), tin (Sn), cobalt (Co) and antimony (Sb) The melted metal mixture may include one or more reactive metals. The reactive metal should preferably: (1) be soluble in the metal (s) diluent (s); (2) have a very low vapor pressure at oxidation / reduction temperature (s); and (3) producing one or more oxides when they react with steam which also has a very low vapor pressure at oxidation / reduction temperature (s). A particularly preferred reactive metal according to the present invention is iron and according to one embodiment, the reactive metal in the fused metal mixture consists essentially of iron. The reactive metal dissolves at least partially within a second metal, or mixture of metals. The metal in which the reactive metal is dissolved is referred to herein as the metal diluent. The metal diluent can also be reactive with steam, in which case it can be selected from the group of reactive metals described above, with the proviso that the metal diluent is less reactive than the reactive metal. Alternatively, the diluting metal can be selected from metals where the oxygen partial pressure (p02) in equilibrium with the metal and oxide together is relatively high. These include nickel (Ni), copper (Cu), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), Cadmium (Cd), rhenium (Re), osmium (Os), iridium (Ir ), platinum (Pt), prayed (Au), mercury (ftg), lead (Pb), bismuth (Bi), selenium (Se) and tellurium (Te). More than one metal diluent can be used in the fused metal mixture. The metal diluent should not be a metal in which the partial pressure of oxygen in equilibrium with the metal and the metal oxide together is extremely low. Preferably, the metal diluent should: (1) combine with the reactive metal to be liquid in the temperature range of 400 ° C to 1300 ° C; (2) have a very low vapor pressure over this temperature range; and (3) have the ability to maintain the reactive metal in solution. According to a preferred embodiment of the present invention, the metal diluent is tin and in one embodiment, the metal diluent consists essentially of tin. However, the fused metal mixture can also include additional divalent metals, particularly copper and nickel. A particularly preferred fused metal mixture for vapor reduction according to the present invention includes iron as the reactive metal and tin as dilute metal e4. Iron has a high solubility in tin fused at elevated temperatures and the melting temperature of the mixture is substantially lower than the melting temperature of pure iron (1538 ° C). Although tin is also reactive with steam, it is less reactive than iron. Due to thermodynamics, vapor reduction reactions to form hydrogen gas require an excess of steam above the stoichiometric requirement. The total steam requirement the proportion of vapor mass required for hydrogen produced) for iron is much lower than for tin at all temperatures and it will preferably oxidize in the fused metal mixture. While not wishing to be bound by any theory, it is believed that some of the reactive tin is oxidized to tin oxide, but is immediately reduced back to tin: 2H20 + Sn? Sn02 + 2H20 (6) Sn02 + 2Fe? 2FeO + Sn (7), Net: 2H20 + Fe - FeO + 2H2 (8) The thermodynamic vapor requirement for tin at © 60 ° C is approximately equal to the thermodynamic steam requirement for iron at 1200 ° C. However, the production of hydrogen using tin ate a reactive metal at 66 (it is not practical since kinetic fds (ie, the reaction rate) are very scarce and therefore, longer residence times are required ( that is, the time that the steam finds contact with the tin.) At 1200 ° C, the kinetics for both iron and tin are excellent, but the vapor requirement for tin is much greater than that for In accordance with the present invention, the residence time that the vapor is in contact with the reactive metal is increased by the use of a metal diluent.For purposes of illustration, a coring of the thermodynamic vapor requirement and the times of normal residence at a temperature of 1200 ° C and various pressures for a dissolved iron form of the present invention (50 wt.% tin ore) as compared to pure tin is illustrated in Tables 1 and 2. Table 1 illustrates the total steam required to produce one ton of hydrogen at 1200 ° C. Table 1
Table 2 illustrates the normal residence times of the steam at a production rate of 4.43 tons of hydrogen per hour. Table 2
It is evident from the data in Table 1 and Table 2 that pure tin systems substantially require. more steam to produce hydrogen than the iron die systems according to the present invention. Table 2 shows that the nominal residence time available for the tin to react with the vapor is considerably less than the nominal residential time available for iron dissolved in tin to react with the vapor. The nominal or nominal residence time is the time available for the steam (process reagent) to pass through the space occupied by the amount of reactive metal used. In Table 2, the fused volume is the amount of metal required by this step in the rate of hydrogen production of 4,439 tons of hydrogen per hour. During this time, ideally, hydrogen will be produced in an amount corresponding to the thermodynamic ratio pH2 / pH20. An amount of reactive metal greater than the stoichiometric amount can be used to increase the nominal residence time, but, the consequence is that it increases the reactor size and the cost. The increased pressure also increases the residence time available between the steam and the reactive metal, however, this also helps the cost. Thus, a significant advantage of using a reactive metal dissolved in a diluent metal according to the present invention, is that the residence time of the vapor within the reactor is increased with respect to the mass of the reactive metal. That is, a given mass of iron will occupy a first volume as pure iron, but the same iron mass will be distributed about twice the volume if the iron is in a mixture of 50 weight percent with a diluting metal such as est. Fig. 1 illustrates a phase diagram for iron and tin adapted from Hari Kumar, K.C., et al .; Calphad, 20, 2, 139-149 (1996). It can be seen from Figure 1 that an effect of adding the iron (the reactive metal) to tin (the metal diluent) is substantially lower than the melting temperature of the iron. The liquid of the metal mixture is reduced from 153 ° C (pure iron) to about 1334 ° C to a fused composition of about 48.7 percent in tin peigno and 51.3 percent by weight of iron. According to one embodiment, it is preferred that the metal mixture be maintained at a temperature above the liquid line AC of Figure 1 (e.g., above 134 ° C). However, a metal-vapor reaction temperature that is too high, significantly helps the operation bostos. For the fully fused tin / iron system illustrated in Figure 1, the melting should be maintained at a temperature above the liquid temperature of about 1 134PC, more preferably at a temperature of at least about 1200 ° C. For the purpose of reasonable economy, the temperature ho should be greater than about 1500 ° C and more preferably not more than about 14Q0 ° C. A particularly preferred temperature range for the fully fused tin / iron mixture is about 12 ° C to 13 ° C ° G. At 200200 * C, approximately 50 weight percent of Iron dissolves in tin with sufficient super heating and the mixture remains in the fused state as the iron is oxidized. Also, the reaction between vapor and liquid iron dissolved in tin to form pure hydrogen at 1200 ° C is also quite vigorous and Ips reaction kinetypes are excellent. In addition, the thermodynamics for the steam / iron system at 1200 ° C are relatively good, requiring an excess of only about 12.2 tons of steam to produce each ton of hydrogen (1.37 moles of steam per mole of hydrogen). According to this modality, it is preferred that the metal mixture initially include at least about 3 weight percent iron in the fused metal mixture, most preferably at least about 10 weight percent iron, even more preferably at least about 20 weight percent. by weight of iron and even more preferably at least about 50 weight percent of Iron in the fused metal mixture. In addition, the amount of iron in the fused metal mixture preferably does not exceed about 86 weight percent and more preferably should not exceed about 80 weight percent. The balance of the metal mixture in a preferred embodiment consists essentially of tin. Accordingly, the amount of tin in the system is preferably not greater than about 97 weight percent, more preferably not more than about 90 weight percent, and even more preferably not greater than about 80 weight percent. weight. The blend of melted metal preferably includes at least about 15 weight percent tin and more preferably at least 0.05 weight percent. less about 20 weight percent tin. Although the present invention requires the presence of a mixture of fused metal, according to one embodiment, insoluble phases such as in the form of particles can be dispersed within the fused metal mixture. This installation of a mixture of fused metal and insoluble phase is called a mixture. According to one embodiment, the vapor is contacted with a mixture including a mixture of fumed metal and a second solid phase, wherein the second solid phase includes particles containing fused metal and is adapted to supply additional reactive metal to the mixture of metal fused. For example, the mixture could include iron-rich metallic particles within the iron / tin melt that is saturated with iron. As the steam reduction process proceeds, the dissolved iron is removed from the molten metal mixture by oxidation of the iron and the additional iron from the iron-rich particles dissolves in the fused metal to keep the metal part fused from the iron. the mixture saturated with iron. Referring to the phase diagram in Figure 1, the composition within the two-phase region defined by point A (83.3% by weight of Fe at 1 134 ° C), point B (84% by weight of Fe to 1 134X ), point C (12% by weight of F & amp;; at 895 ° C) and point D (3% in Fe peao at 895 ° C) includes an iron / tin melt with approximately 3% 9? It receives 84% by weight of total iron, corj a part of the iron as metallic particles rich in iron in the fusion. At a given temperature between approximately 895 ° C and approximately 1334 ° C, as the iron is removed from the fused metal due to the oxidation of iron, the additional solid iron from the iron-rich particles will dissolve, maintaining it in such a way the iron level in the melt in volume saturation until the solid iron is consumed. This replacement of iron that is lost in oxidation by iron that originates from the iron-rich particles maintains the activity of atfa iron, which, in turn, maximizes the production of hydrogen. For example, at a temperature of about 950 ° C and about 50% by weight of total iron, the fused metal mixture will include about 4% by weight of iron dissolved in the system. As the dissolved iron is oxidized, the additional iron metal of the iron-rich particles will dissolve to maintain 4% by weight of iron dissolved in the melt. Therefore, the activity of iron remains undisturbed as a consequence of the dissolution of the iron-rich particles. Thus, according to this embodiment, the mixture, comprised of the mixture of fused metal and the iron-containing particles, is maintained at a temperature below the liquid temperature of 1134 ° C and is at least about 895 ° G. , more preferably from about 900 ° C to about 1134 ° C. An advantage of such a method is that the activity of the iron remains constant and in fact close to one, and therefore, the speed of hydrogen production remains constant and is maximized throughout the vapor reduction process. The desired effect of the constant activity of the reactivated metal could also be observed if the process were carried out within the region of the rupture opening of Figure 1; however, iron activity could be somewhat less than one. A thermodynamic relationship exists between the partial pressure of hydrogen in the gas discharge, the reaction temperature and the weight percent of iron in the fused metal composition. The thermodynamic quantity, referred to as the iron "activity", varies as a function of iron concentration and strongly influences the proportion of hydrogen to water in the gas discharge. Oxygen production is maximized by operating within the phase regions that establish a high-wire activity over a wide range of composition through the use of a second phase in equilibrium with the reaction phase. This applies to both the liquid-liquid region, above the AC line in Figure 1, as well as to the solid-liquid region, below the AC line and to the right of the AB line. However, the present invention or excludes the operation in the liquid phase rich in iron. Figure 2 illustrates the relationship between the level of hydrogen in the gas discharge as a function of iron content in the fused metal mixture. Figure 2 was calculated based on the thermodynamics of the reaction at 1225 ° C. It is evident that the production rate of hydrogen is rapidly reduced as the iron content drips from 20 weight percent to 10 weight percent. Figure 3 illustrates the production of hydrogen as a function of temperature axis and iron content. At levels below about 20 weight percent iron and temperatures above about 1134 ° C, the production capacity for hydrogen is uneven since: (1) pH2pH20 leaks significantly; and (2) only short periods of time are available before the gas flows (i.e., metal oxide and vapor reducing agent) have to be changed.
From this maze, the steam is contacted with the mixture of fused rrietal to generate hydrogen and convert the reactive metal into metallic oxide. The steam is contacted with the metal mixture fused in a manner that promotes good mixing and contact with the fused metal mixture. For example, the pin may be contacted with the metal mixture fused by injection through a submerged lance on the top or through a porous ceramic diffuser placed at the bottom of a reactor. Preferred reactor systems in this regard are discussed below. The temperature of the reactant can be controlled to maintain a substantially constant temperature by controlling the incoming vapor temperature and amount and / or by adding oxygen to the reactor. The steam reduction reactor can be maintained at high pressure if necessary for the appropriate residence time in the reactor, as discussed above. For example, it may be desirable to maintain an ejected pressure, such as at least about 15.3 atmospheres (225 psi). Also a slightly elevated pressure may be beneficial to provide a stream of hydrogen gas with sufficient pressure for transmission (for example, a line pressure of approximately 200 psi). However, the significantly increased pressure aids the capital post and therefore, the pressure in the steam reduction reel is preferably not greater than about 600 psi and more preferably not greater than about 225 psi. According to the present invention, a slag cap is maintained on the fused metal mixture. A slag layer provides a number of advantages, including preventing iron oxide from leaving the reactor. The temperature in the vapor reduction reactor should be sufficient to maintain a slag layer that forms over the metal mixture in the fused state over a range of compositions.As the reactive metal is oxidized, a reduction will occur in the concentration of the reactive metal in the metal mixture and the metal mixture should remain fused as the reactive metal is oxidized, and the range of compositions for the fused metal discussed above with respect to FIG. Preferred slag required to ensure slag fluidity and reactivity, a prevention spray can be adjusted, as necessary, for a given temperature, for example, streams can be added to the reactor to adjust the slag properties. indicated by the liquid surface of Si02, FeO, CaO, MgO, Na20 and K2p, however, sulfur and other cations can be incorporated in this after slag to ensure satisfactory slag chemistry. The metal oxide (e.g., zinc sulfate and / or magnetite) that is generated by the vapor reduction can advantageously be trapped (dissolved or suspended) in the scoria layer inside the reactor. At the preferred temperatures, the iron oxide is incorporated into the slag, which is lighter than the metal mixture. Therefore, as the dissolved iron is consumed from the fused metal mixture, the iron oxide rises through the fused metal and contributes to the slag layer on top of the fused metal. An advantage of this embodiment of the present invention is that the oxide formed in the reaction of the reactive metal with the vapor has a density that is less than the density of the fused metal mixture, by which the oxide rises in the layer give scum Preferably, the metal oxide is at least about 10 percent less dense than the mixture of metal fused. This also allows the metal to sink from the slag layer to the mixture of r) fused in the reduction of the metal oxide. As discussed above, this accumulation of iron oxide in the slag may require the addition of a flow such as Si02., FeO, CaO, gO, Na20, KzO or mixtures thereof to keep the slag in the preferred condition with respect to viscosity, reactivity, foaming, and the like. The fused metal mixture should be contained within a suitable reactor in order to maintain the appropriate reagent conditions. In addition, the reagents should be provided in a manner conducive to good mixing and high contact surface area. The high temperature reactors suitable for establishing t >They are used in the chemical, and especially metallurgical, industries. A preferred reactor system according to the present invention uses a lance submerged in the upper part to inject the vapor into the fused metal. Such reactors have been used in the commercial production of tin tin ore (cassiterite). Examples of reactors that use a submerged lance on the top to inject the reagents are described in the U.S. Patent. No. 3,905,807 by Floyd, US Patent. No. 4,251, 271 by Floyd, U.S. Patent No. 5,251, 879 by Floyd, U.S. Patent. No. 5,282,881 by Bajdock ef al. , Patent of E.U. No. 5,308,043 by Floyd ef al. and US Patent. No, 6,066,771 by Floyd ef al. Each of these US Patents it is incorporated herein by reference in its entirety. Such reactors are capable of injecting reagents (e.g., vapor) into the fused metal ¾ extremely high speeds, about ach 1, thereby promoting good mixing of reactive IQS. A reactor incorporating a lance for steam injection is illustrated in Figure 4. The reactor 400 includes refractory side walls 402 which are adapted to contain the mixture of fused metal 404. The heating means (Vio illustrated) can be provided, if it is necessary, to maintain the temperature inside the reactor 400. A submerged lance at the top 408 is placed through the upper wall of the reactor 41 2 and is adapted to inject the vapor into the metal mixture 404 at a high speed. Preferably, the submerged lance at the top 408 terminates and injects steam below the surface of the slag layer 406 and close to the interface of the fused metal mixture 404 and the slag layer 406. As the steam is irithoduced through the lance 408, the iron of the metal mixture 404 oxidizes the iron oxide. The iron oxide rises and accumulates in a slag layer 40 ^ 6. A gas product 41 including the hydrogen gas co-mixed with the vapor is withdrawn from the outlet port 41 0, after which the overhead steam can be condensed to form a stream of substantially pure hydrogen gas. The steam reduction process is continued until the rate of hydrogen production is reduced to a sufficiently low level. Thereafter, a reducing agent is introduced into the reactor containing the mixture of fused metal and the slag to reduce the iron oxide back to the metal. The point at which the vapor reduction process is completed and the metal oxide reduction process begins, can be easily determined based on economic considerations. That is, at the same point, the rate of production of hydrogen in the steam reduction reactor will be reduced to a point which is economically advantageous to complete the steam reduction and begin the metal oxide metal regeneration. At this stage of regeneration, which can be observed as reductive cleaning of the slag, the iron oxide in the slag is reduced and returned to the melt as iron. This is achieved by decreasing the oxidation potential of the system by introducing a reducing agent into the reactor. The reducing agent decreases the oxidation potential of the system thereby driving the iron back into the melt. The reducing agent can be carbon monoxide, carbon and / or other carbon source. According to a preferred embodiment, the oxidation potential of the system is reduced by injecting particulate carbon, hydrocarbon or hydrocarbon liquor into the slag with a gas containing oxygen under conditions of intense mixing. The particulate or hydrocarbon carbon may include coke, coal or other organic material. A liquid hydrocarbon, such as # 6 or another oil can also be used. Waste materials such as waste tires can also be used. Waste tires can advantageously supply additional iron to the reactor to be made from incidental loss of iron. A spear is preferred in the upper part to introduce the air or other oxygen-containing gas into the reactor in a way that ensures good pumping. Before the injection of urta composition re, ducting, the reactor can be purged, such as steam, to remould any hydrogen from the reactor. After the reductive cleaning of the slag is complete, the reactor can again be purged, with air or steam, for the purpose of removing any carbon that can be dissolved in the iron and / or for the purpose of removing any of the other carbon atoms. A vessel that may already be a fusion or Escariá, which would otherwise contaminate the hydrogen produced when the vapor is re-introduced into the reactor. In a preferred embodiment according to the present invention, a reducing agent derived from a carbon source such as carbon and a <source; and oxygen, as air or oxygen-enriched air, is injected into the mixture of fused metal and scouting potato. The carbon can be injected through the lance submerged in the upper cone with the aerator or it can be added separately. One advantage is to use coal as the source of reducing agent, because, compared to oil and gas, it is both abundant and relatively cheap. Coal can also supply iron to the reactor to be processed by the iron that is lost during processing. Waste tires and other waste materials can also supply some iron. The metal oxide reduction process is continued until a sufficient amount of iron metal has been re-dissolved in the fused metal mixture. Preferably, the reaction conditions when operating in the manner to reduce the metal oxide to metal are substantially identical to; the conditions during steam reduction. That is, it is preferred that the temperature and pressure of the metal oxide reduction reactor be same or very similar to the temperature and pressure of the steam reduction reactor. In this way, the temperature is at least preferably above the liquid (for example, about 130 ° C for the tin / iron system) and more preferably is at least about 1200 ° C. Preferably, the temperature does not exceed about 1400 ° C and more preferably does not exceed about 1300 ° C. In a particularly preferred embodiment, the temperature is at approximately 1200 ° C in both reactors and the pressure is slightly above the atmospheric pressure in the vapor reduction reactor and slightly below the atmospheric pressure in the reduction reactor of the reactor. metallic oxide Referring now to Figure 5, a reactor 500 operating in a metal oxide reduction mode is illustrated. Preferably, the reactor is physically identical to the steam reduction reactor illustrated in Figure 4, and includes insulated side walls 502. The metal mixture 504 initially includes predominantly tin, although some iron will still be present. The slag layer 506 includes the iron oxide that was formed during the vapor reduction process described above. The carbon 514, such as in the carbon form, can be injected through the lance 508 which is placed through the upper wall of the reactor 51 along with an oxygen source such as oxygen enriched air. Alternatively, the carbon can be added to the reactor separately and the source of gaseous oxygen can be injected through the lance. Under the reducing conditions maintained in the metal oxide reduction reactor by the addition of carbon and oxygen, the iron oxide is reduced back to the iron, which then re-dissolves into the 504.50 mixture of fused metal. 516 such as carbon dioxide and nitrogen can be removed through the exit port 510. In the metal oxide reduction stage, the ash formed from coal will also be incorporated into the slag. The slag, which can be pzozolian when CaO is added as a stream, can periodically or continuously be extracted, cemented and can be used as a replacement for Portland cement. Alternatively, the slag can be partially granulated by rapid cooling with water. The granulated slag can be drained well and placed to be discarded. Impurities in the coal (eg, sulfur, chlorine and fluorine) which are con tinned during combustion in gaseous species (such as sulfur dioxide, hydrogen chloride and hydrogen fluoride) can be removed by wet washing. Alternatively, the sulfur can be converted to ammonium sulfate, which is useful as a fertilizer compound, and the remaining impurities reacted to make them solid so that they can be directed to waste. The carbon dioxide and nitrogen from the air and fuel are the only gaseous effluents from the metal oxide reduction process. Controlling the oxidation potential of the slag controls the amount of iron oxide in the slag that is reduced to iron which is subsequently reported in the melt during the reduction of metal oxide. This can be achieved by controlling the relative amount of carbide (or other carbonaceous carbon) and oxygen that is injected into the slag system. Some of the iron oxide will dissolve in the slag, the amount determined, by the chemistry of slag. Another part of the iron oxide may be present in the esoteric state as particulate solids if the oxide is saturated in iron oxide. According to the preceding, it is apparent that two or more reactors can be operated in parallel for the production of hydrogen in a continuous manner. As iron is removed from the metal mixture by melting it in the steam reduction reactor, and as the iron oxide is reduced to metal in the metal oxide reduction reactor, its functions can be reversed by changing the flows towards in and out of the reactors. Although the functionality of the reactors is reversed, there is no movement of metal or metal oxide in or out of the reactors. This has a favorable and significant impact on the cost. The reactors can use a single top submerged lance for steam injection or the injection of carbon and oxygen to form carbon monoxide. Alternatively, a reactor with two larizas (one for the steam and one for the carbon / oxyne) can be used. Additional ports for steam injection may also be provided, such as on the sides of the reactor. A working diagram illustrating the continuous generation of hydrogen using two reactors according to the present invention, is illustrated in Figure 6. The hydrogen generation process employs two reactors
602 and 604 wherein one of the reactors operates in the vapor reduction mode while the other operates in the metal oxide reduction mode. As illustrated in Figure 6, reactor 602 is operating in steam reduction mode and generates hydrogen and reactor 604 is operating in metal oxide reduction mode. The steam is provided by heating the water in recovery boilers 602 and 610. Before heating in the boilers, the water must undergo 612 purification, such as using reverse osmosis and de-ionization to remove contaminants that may affect the operation. of) boiler or introduce impurities in the hydrogen product gas. The steam was produced in the boilers and is provided for the reactor 602 at a superheated temperature which is sufficient to maintain the isothermal conditions within the steam reduction reactor 602 at the operating temperature, for example, about 1200 ° C. The steam is injected into the reactor 02 through a lance submerged in the upper 608. The lance submerged in the upper part provides good mixing and a high contact surface area between the steam and the fused straw metal mixture promote the reaction of steam reduction / oxidation of metal. Reactor 602 is sealed to prevent the discharge of hydrogen and steam from the reactor. Also, the reactor can be placed under modest pressure to provide a sufficient contact time for the steam and to supply the hydrogen under pressure. Other materials can be added to the reactor if necessary. For example, flows 614 can be added to control the properties of the slag layer that is formed above the fused metal mixture as the vapor reduction reaction oxidizes the metal. Possible flows include Si02l FeO, CaO, MgO, Na2Q or K20. Additionally, other materials such as tin compounds, cassiterite ore or other materials such as iron or mineral compounds can be added to be processed by loss of metal values. Give acidosp to a particularly preferred modality, e | Cassiterite mineral (Sn02) is injected into the reactor to work for tin losses. A gas containing hydrogen that includes hydrogen and excess steam is removed from the reactor 602. The hydrogen-containing gas can be passed through the recovery boiler 606 to provide heat for additional steam, thereby conserving the heat values. The gas in the hydrogen-containing gas stream may also include some contaminants, such as tin oxide sub-oxide (son), hydrous tin sub-oxide (Sn02h2), and slag-entrained particulate Ips (frozen) They are volatilized or come out of the fused metal and slag bath, and such contaminants can be removed in a bag filter chamber 616. For example, volatile tin compounds can condense from the gas stream and, along with the particulate slag, Captured either in the recovery boiler or in the bag filter chamber. After being captured, these materials can be granulated 618 and optionally provided to any reactor 602 operating in vapor reduction mode or reactor 604 which operates in the metal oxide reduction mode for recovery of the metal alloys and control of the slag chemistry After removal of the contaminants, if any, the hydrogen gas stream is treated in a condenser 620 and / or cooler (not shown) to condense the excess vapor from the hydrogen gas stream and form a stream of hydrogen gas. hydrogen gas of high purity 622. The condensed water of the hydrogen gas stream can be recycled for the production of added steam Simultaneously, the metal oxides are reduced in the reactor 604. The metal oxides are reduced by a reducing agent such as CO, which can be formed by injecting carbon 624 (or other carbonaceous material) and oxygen 626 through a submerged lance at the top 628. As with reactor 602, the submerged lance at the top 628 provides good mixing and contact surface area between the reagents. The oxygen-containing gas should also be injected using a submerged lance on the top or similar device. It is possible to add the particulate carbon to reactor 604 by another means, such as simply dripping the carbon in the reactor. The ash-forming minerals that are typically part of the coal (or other carbonaceous material) used together with the oxygen produce the reduction of the reactive metal oxides, contribute to the slag layer inside the 604 reactor. When the 624 carbon is used and exists Suitable calcium oxide (CaO) in the slag, the slag cap can be a pozzolanic derivative for sale. As with reactor 602, other materials such as fluxes can be injected into reactor 604, for example, to control the slag properties such as slag fluidity or the tendency to froth. The gas discharge from the metal oxide reduction reactor 604 may include carbon dioxide, nitrogen and some air pollutants. carpon such as sulfur. The heat of the gas discharge can be retained in the recovery boiler 610 where it is already generated. The gas stream can thus be treated in a bore chamber 630 to remove particulate contaminants. The remaining gases can be treated in a limestone scrubber 632 to form environmentally benign combustion shaft gases and sulfur gypsum that originates from the coal. Alternatively, the sulfur can be treated with anhydrous ammonium to form ammonium sulfate, a compound useful for fertilizing the soil. In this way, as the iron is consumed from the metal mixture fused in the steam reduction reactor 6p2, and as the iron oxide is reduced to metal in the metal oxide reduction reactor 604, its functions can reversed by changing flows in and out of reactors. Before changing Ips gas flows, reactors can be purged to remove residual gases and contaminants, if any. According to the foregoing, hydrogen gas can be produced in a substantially continuous manner. The hydrogen gas that is produced according to the present invention can preferably have a high purity. Preferably, the gas stream includes at least about 30 volume percent of hydrogen with the remainder composed mainly of water in the vapor form. Preferably, the purity of the hydrogen is greater than about 99% or more preferably greater than about 99.9% after the removal of the wastewater in a condenser. An advantage of the present invention is that the hydrogen gas requires the separation of another species of gas such as carbon monoxide and carbon dioxide as is the case for the hydrogenation produced either by methane vapor reformation or by gasification. coal, whose? two methods cover the volume of hydrogen currently produced. In the event that the carbon species (eg, CO) are present in the current of g $ s due to the dissolved carbon in the fused mixture, the gas can be extracted and burned at the fuel value until the purity of the gas. hydrogen reaches a sufficient level. That is, any dissolved carbon will preferentially react with the vapor to form CO before large amounts of hydrogen are produced by oxidation of the reactive metal. In addition, the method and apparatus of the present invention allow the production of high volumes of pure hydrogen gas at a low cost. The hydrogen gas has a fuel value of about 51.6-23 BTU / lb and is useful as a com- pound of a flue gas. Hydrogen can also be used for hydrogenation processes and semiconductor fabrication. In addition, hydrogen is used directly as a fuel ép an energetic cell, such as the proton exchange membrane energy cell (PEMFC). One aspect of the present invention relates to the treatment of coal to produce carbon energy value while minimizing the discharge into the atmosphere of harmful derivatives which are typically aspic with the conversion of carbon to energy. The method allows the extraction of the available energy content of the coal in the form of a medium BTU gas while reducing the atmospheric discharge of the harmful derivatives. Coal exists in relative abundance in the United States and several other regions, including third world regions with underdeveloped energy production infrastructure. One of the problems associated with the use of coal is that coal must typically be cleaned or purged of its mineral content, including sulfur.; however, there is usually an additional need to wash the post-combustion gas to meet environmental standards. An advantage of the present invention is that the coal feed tank may include low grade coal including high sulfur carbon and other low grade carbons. Such low grade carbons are readily available and available at low cost. As used herein, the term "low grade carbon" refers to carbon having a sulfur content in excess of 2 weight percent and an ash content in excess of about 10 weight percent. Generally, the method of the present invention includes providing the carbon feed tank to a hydrogenation unit and contacting the coal feed tank with a treatment gas including H2 produced according to the foregoing. The hydrocarbons in the coal that are volatile will react with the hydrogen to form methane (CH4). The exhaust gases from the hydrogenation unit may be washed, if necessary, to produce a high, clean BTU gas product. A part of this gas product can be burned in a combined cycle generator that takes advantage of the thermal to electrical conversion efficiency of the generator. Another part of the gas product can be blended in a conventional boiler with the non-volatile Carbon that is formed in the hydrogenation unit. The carbon will be essentially free of sulfur because the hydrogen gas treatment is a strong desulfurizing agent. In one embodiment, another part of the carb that is produced in the hydrogenation unit can be recycled back to the metal oxide reduction stage where the metal oxide is reduced back to the reactive metal. In this way, carbon is advantageously divided into volatile (locked with hydrogen) and fixed carboho (reacted with oxygen). Referring now to Figure 7, coal 702, optionally with other organic, is first transported to a pre-heater 704 where the temperature of the coal rises. The heated coal is thus transported to a hydrogenation unit 706 where the carbpn is contacted with hydrogen gas 705 which has been formed according to the method described above. The hydrogenation unit 706 may be a fluidized bed reactor or another reactor that is suitable for the treatment of particulate carbon. The unit is preferably operated at ambient or near ambient pressure, such as a pressure of no more than about 5 psi. A cost expense of the present invention is that the hydrogenation unit 706 is not operated at a high pressure substance J. The grossly elevated pressures produce additional methane, a gas with a very high BTU content. However, for the purpose of converting coal into clean energy, it is more cost effective to produce carbon monoxide from combustible gases and hydrogen from coke, a residue of the hydrogenation stage. The gases derived from the reaction between the coke and the steam (CO &H >) are combined with the methane from the hydrogenation to produce a medium valuable BTU gas. The reaction in the hydrogenation unit 706 is preferably carried out at a temperature of at least about 70 ° C and preferably not more than about 1100 ° C, such as from about 80 ° C to about 900 ° C. The reaction that occurs in the hydrogenation unit is exothermic and therefore, the need for external heat addition is minimal. Coal is a complex mixture of chemical compounds that are mainly organic compounds. While coal is predominantly a hydrocarbon, impurities such as sulfur and nitrogen are trapped in the carbon. These impurities, released as the coal burns, lead to the formation of sulfuric acid and nitric acid if they are released into the atmosphere and must be flushed from the gas discharge at a typical coal-based power plant. furtherWhen carbon is burned, carbon combines with the oxygen in the atmosphere and forms a well-known greenhouse gas that traps the heat of the earth. According to the present invention, when the coal 702 is treated in the hydrogenation unit 7O6 with the hydrogen treatment gas 705, e! Coal does not burn. Actually, it is heated to remove the volatile components in it carbon. These volatile components advantageously form a high product BTU comprised in their. majority of methane. The residue of the volatiles removal is purified by the action of hydrogen, including the removal of sulfur and nitrogen, and the resulting purified carbon (ie, coke 707) can: (a) be combusted in a conventional methane boiler and without excessive formation of harmful derivatives; (b) converted to carbon monoxide and hydrogen, the gases of which are added to the methane in the hydrogenation reactor 706 to produce an average BTU gas for combustion; (c) activated by oxygen and steam to form an activated carbon 716; or d) some combination of the aritériorés. The gas stream containing methane that is produced by the hydrogenation reaction can & passed through a recovery boiler 708 to preserve the heat value of the gas stream. Thereafter, upa limestone, lime or ammonium launder 710 can be used to remove contaminants from the gas stream containing methane such as sulfur, thereby producing a gas containing methane of high purity 71 ?. The sulfur in the coal will form hydrogen sulfide (H2S) that can be washed out of the methane gas stream. It is advantageous to wash the methane gas stream before combustion, if any, since combustion creates a higher volume gas stream. The methane gas can be combusted at the site to generate electricity, or it can be treated to remove CO (if any) and proportions to end users as a pipeline gas. In addition, a part of CH4 can be cycled back to the other unit operations to provide heat in process. For example, a portion of the CH4 can be diverted to the super steam heater 714. The hydrogenation treatment advantageously removes the impurities in the coal 702 to form a clean coke product 707. The coke 707 product can be treated in an activation / oxidation unit. 71 d if necessary, to form: (a) activated carbon cleaned 716, (b) a clean coke, (c) a mixed gas comprised of hydrogen and carbon monoxide or (d) some combination of the preceding. According to one embodiment of the present invention, a part of the coke 707 can be cycled back to the metal oxide reduction reactor (Figure 5) for the reduction of the metal oxide. The carbon will become CO and the ash will be incorporated into the slag that can be extracted periodically. The remaining coke from the hydrogenation unit 706 can be burned in a conventional methane boiler for the production of additional energy. In addition, a part of the hydrogen gas 705 that is produced by the steam reduction can be diverted from the hydrogenation unit 706 and used directly as a fuel source, either alone or in combination with the methane gas. For example, hydrogen can be ignited directly in a boiler, internal combustion engine d energy cell. As discussed above, the primary feed reservoir to the hydrogenated unit of the present invention can be a low grade carbon as well as a high grade carbon. In fact, the low grade coal feed tank can be advantageous since they are generally available at a low GOSÍO. In one embodiment, the coal feed tank is a low grade carbon having at least 1 weight percent sulfur, more preferably at least about 2 weight percent sulfur. The coal can be pre-treated such as to grind the coal and remove the moisture. For example, it is desirable to grind the carbon to reduce the maximum particle size to no more than about 1 mm. When the feed tank is crushed coal, the hydrogenation process results in a finely divided and highly purified carbon product. The hydrogenation treatment according to the present invention converts the volatiles (for example, hydrocarbons) in the coal to methane. Preferably, at least about 90 weight percent, more preferably at least about 95 weight percent and still more preferably at least about 99 weight percent of the volatile matter is converted to methane. As discussed above, coal often includes contaminants, including sulfur-free levels. The method of the present invention advantageously and simultaneously distills the contaminants from the volatile matter fraction of the carbon as well as the residual oxide. Sulfur, for example, reacts with hydrogen gas and forms hydrogen sulfide, which can be easily removed from the waste stream. In addition, the method of the present invention allows for the production of enology of the coal feed tank while significantly less carbon dioxide is produced per kilowatt-hdra of energy produced than what is typically produced in a conventional coal-fired power plant. . This lower ratio of carbon dioxide to kilowatt-hours of electricity produced is increased because the method of the present invention converts carbon, a solid fuel, into a gaseous fuel B † U medium. The thermal to electrical efficiency (expressed as a percentage) for a solid fuel varies? ß the low 20s to the low 30s while for a fuel, the conversion from thermal to electric is 55 to 60 percent. The reduction in the emission of carbon dioxide is an important environmental factor and helps to value the method more. As discussed above, the carbon that was produced in the hydrogenation unit can be an activated carbon. Activated carbon is an amorphous form of carbon characterized by the high absorption of various gases, vapors and colloidal solids,. The internal surface area. The activated carbon exceeds several hundred m2 / gram and the density is not greater than about 0.85 g / cm3. The activated carbon has a high value and can be used for the purification of water and air, waste treatment, removal of mercury (Hg) and SOx from flue gases and the like. In this way, the hydrogenation process when applied to the coal provides a gas stream of high BTU value as well as a valuable derivative. In addition to coal, other hydrocarbon-producing feed tanks can be treated in the same way to produce a valuable product gas that includes methane (CH4). The feed tank is supplied to a hydrogenation unit where large volumes of a gas composition including H2 are contacted at an elevated temperature such that a part of the feed tank is converted to CH4. One advantage of the present invention is that the feed tank can be virtually any hydrocarbon-producing feed tank, including those that are available at a net cost that is still negative or very low. In one embodiment, the feed tank is municipal waste. Municipal waste can include normal commercial and household waste, hazardous waste, animal waste, sewer sludge, automobile crusher waste (DTA), waste rubber tires and the like. Municipal waste is commonly available at a net negative cost since municipalities will typically pay a "rolling" tax for the removal and destruction of the waste. According to the United States Environmental Protection Agency, the United States generated 220 million tons of municipal waste in 1998. The amount of waste per person has steadily increased from 2.7 pounds per person per day in 1960 to 3.7 pounds per person. per day in 1980 and approximately 4.5 pounds per person per day in 1998. The components of municipal waste (before recycling) in the United States in 1998 according to the EPA are listed in Table 3. Table 3. Average Municipal Waste Composition
When the feed tank is municipal waste, the feed tank can be treated and separated if necessary. For example, magnetic metals such as iron and steel can be easily removed and sold for waste. Optionally, cellulose-based materials (eg, paper and wood) can also be removed from the feed bin to reduce the level of oxygen compounds in the feed bin. For example, air separation can be used to separate its relatively dry, lightweight fraction from the waste that includes, for example, paper and cardboard, size and wood trim. The remaining material, which includes food waste, plastics, rubber, leather, non-ferrous metals and vidriq, can be separated by hydraulic classification. Non-ferrous metals and glass can be recycled off-site. . As discussed above, the term municipal solid waste can include not only general and residential commercial waste, but also specific waste such as automobile crusher waste (DTA) or "paper fluff". DTA, essentially the non-metal components of a recycled car, is a heterogeneous mixture of plastics, glass, rubber, fiber, non-recovered metal and dirt. The plastic content of DTA is typically 20 percent in weight and increases as the amount of plastic used in car building increases. The DTA is currently filled by land and legislation has been proposed in some regions to classify the DTA as a harmful waste, which dramatically increases the cost of distribution. In this way, the conversion of DTA to a useful product gas could allow significant ecological and environmental savings. Municipal waste, such as coal, can be divided into volatile and fixed carbon by the application of heat. The chemical composition of the conducted volatiles from municipal waste can be represented generically as CHX. In this way, the reaction that occurs when the waste is contacted with large volume of hydrogen gas in the hydrogenated unit can be written as; 0.5 (4-x) H2 + CHX? CH4 (9) Advantageously, a large volume of combustible gas is produced from the waste and according to the method of the present invention. Approximately 48,550 cubic feet of gas amounting to approximately 19.9 million BTUs can be generated from 1 ton of municipal waste. The gas is comprised of approximately 82 percent carbon monoxide, 16 percent methane, and 2 percent hydrogen, and has approximately 4 0 BTU per cubic foot. According to another embodiment, the feed tank can be a hydrocarbon producing substance such as crude oil, asphaltic areha or a similar substance. Crude oil is a mixture of liquid hydrocarbons. It is extracted from the earth's crust to be used as fuel and various petroleum products. Because the crude oil is a mixture of amplified constituent variants and proportions, the physical properties vary widely and several crude oils have a very low value due to the contaminants in the oil. The present invention advantageously allows the treatment of such low grade crude oils to produce a useful gas product. Asphaltic sand, also called bituminous sand, is a deposit of partially consolidated sandstone or sandstone that saturates with highly viscous asphalt. Oil recovered from asphalt sands is commonly referred to as synthetic crude and is a potentially significant form of fossil fuel. However, recovery of the oil from the asphalt sand is difficult and expensive. The present invention advantageously allows the production of a useful product gas of asphaltic sand of another form of low value. It will also be appreciated that a combination of two or more of the above-described components can be used as the reservoir of alirpentation. For example, a separate municipal waste stream can be complemented with pulverized coal. Yet another aspect of the present invention is directed to the production of ammonium using hydrogen gas and nitrogen gas as reagents. One of the important aspects of the method according to the present invention is the on-site processing of large quantities of H2 at a relatively low cost. It is believed that one of the major obstacles to the methods described in the prior art for the production of ammonium is the need for high volumes of hydrogen gas and the high cost associated with hydrogen gas. According to the present invention, high volumes of hydrogen gas can be generated economically in place. In accordance with the present invention, nitrogen and hydrogen are combined in an H2: H2 molar ratio of about 3: 1 in order to maximize the production of ammonium (NH3). In a typical ammonium production method, a gas including hydrogen and nitrogen is comprised at about 200 atmospheres pressure and is passed over a metal catalyst at a temperature of from about 380 ° C to about 450 ° C. A method for producing ammonium that incorporates the preceding hydrogen and methods for the production of nitrogen gas; is illustrated in Figure 8. For the production of hydrogen, water 801 is propounded to urra caldera 802 and steam is supplied to one of the reactants 810 or 812. Hydrogen gas thus passes to a condenser 820 to remove the water and it thus supplies an ammonium synthesis cycle 848. Simultaneously, air 800 is supplied to an oxidation reactor $ 11 to distill oxygen from the air, so as to provide nitrogen gas stream 825. In the embodiment illustrated in Figure 6, reactor 811 is the metal oxidation reactor while reactor 813 is the metal oxide reduction reactor. Advantageously, a single reactor can be used to provide reduction gas for both hydrogenation production operations and nitrogen production. In this manner, the hydrogen gas 824 and the nitrogen gas 825 are supplied in an ammonium synthesis cycle 648. The ammonium synthesis cycle preferably operates at elevated pressure, such as up to about 200 atmospheres. In addition, the ammonium synthesis cycle 848 operates at an elevated temperature and can catalyze a catalyst. L, to production of ammonium hydrogen and nitrogen is used in: Patent of E.U. Nd. , 600 (571 by McCarroll et al., U.S. Patent No. 4,298,588 by Pinto, and U.S. Patent No. 4,088,740 by Gaines.) Each of the above U.S. Patents is incorporated herein by reference in its entirety. The resulting ammonium can be used in a number of applications, for example, ammonium can be converted to urea for use in fertilizers.Ammonium can also be used to reduce NOx emissions from laé coal-fired power plants and -for The preparation of various ammonium-containing compounds While various embodiments of the present invention have been described in detail, it is apparent that modifications and adaptations of those embodiments will occur to those skilled in the art. and adaptations are within the spirit and scope of the present invention.