GASIFIER HAVING AT LEAST ONE CHARGE TRANSFER ELECTRODE AND METHODS OF USE THEREOF

Gasifiers that may be used for gasifying hydrocarbon-containing materials are disclosed. Methods for use of such gasifiers are also disclosed. In an embodiment, a gasifier includes a gasification reaction vessel having one or more electrodes positioned therein. The one or more electrodes may be used to alter a chemical and/or thermodynamic equilibrium of the gasification reaction. For example, the one or more electrodes may be used to make the oxidation zone more oxidizing and/or to make the reduction zone more reducing such that oxidation and/or reduction reactions are favored. Electrodes in such gasifiers may, for example, be used to alter the mix of products produced by the gasification reaction, to lower the gasification reaction temperature, to enable altering the dimensions of the gasifier (e.g., to make the gasifier smaller) without sacrificing efficiency, and/or to speed up startup and/or shutdown.

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Description
CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 61/753,285 filed on 16 Jan. 2013, the disclosure of which is incorporated herein, in its entirety, from this reference.

BACKGROUND

Gasification is a process that converts organic or fossil based carbonaceous materials into fuel gases (e.g., carbon monoxide, hydrogen, methane, etc.). Depending on the feedstock, additional gases may be generated, such as carbon dioxide and nitrogen. Gasification is achieved by reacting the feed material (e.g., wood, coal, municipal solid waste, recycled tires, refuse derived fuel (“RDF”), and the like) at high temperatures (e.g., >700° C.), without substantially any combustion, with a controlled amount of oxygen and/or steam. The resulting gas mixture is called syngas (from synthesis gas or synthetic gas) or producer gas and is itself a fuel. The power derived from gasification and combustion of the resultant gas is considered to be a source of renewable energy if the gasified compounds were obtained from biomass.

The advantage of gasification is that using the syngas is potentially more efficient than direct combustion of the original fuel because it may be combusted at higher temperatures or even in fuel cells. Syngas may be burned directly in gas engines, used to produce methanol and hydrogen, or converted into liquid fuels. Gasification may also begin with material that would otherwise have been disposed of such as biodegradable waste. In addition, the high-temperature process refines out corrosive ash elements such as chloride and potassium, allowing clean gas production from otherwise problematic fuels. Gasification of fossil fuels is currently widely used on industrial scales to generate electricity.

SUMMARY

Embodiments disclosed herein are related to gasifiers and methods for using such gasifiers for gasifying hydrocarbon-containing materials. The gasifiers disclosed herein include a gasification reaction vessel having one or more electrodes positioned therein. The one or more electrodes may be used to alter the chemical and/or thermodynamic equilibrium of the gasification reaction. For example, the one or more electrodes may be used to make the oxidation zone more oxidizing and/or to make the reduction zone more reducing such that oxidation and/or reduction reactions may be favored. The one or more electrodes in such gasifiers may, for example, also be used to alter the mix of products produced by the gasification reaction, to lower the gasification reaction temperature, to enable altering the dimensions of the gasifier (e.g., to make the gasifier smaller) without sacrificing efficiency, to speed up startup and/or shutdown, or combinations thereof.

In an embodiment, a gasifier is disclosed. The gasifier includes a reaction vessel configured to gasify at least one hydrocarbon-containing feed material. The reaction vessel includes at least one oxidation zone, at least one reduction zone, and at least one electrode that is positioned in the reaction vessel and is operably coupled to an electrical power source. The electrical power source and the at least one electrode may be configured to alter a chemical and/or thermodynamic equilibrium in one or more of the at least one oxidation zone or the at least one reduction zone. For example, the electrical power source and the at least one electrode may be configured to alter the chemical and/or thermodynamic equilibrium by making at least one of the at least one oxidation zone more oxidizing or more reducing or make the at least one reduction zone more reducing or more oxidizing.

In another embodiment, a method of gasifying a hydrocarbon-containing material is disclosed. The method includes providing a gasifier that includes a reaction vessel having at least one oxidation zone, at least one reduction zone, and at least one electrode positioned in the reaction vessel and charging the reaction vessel with a hydrocarbon-containing material and initiating a gasification reaction in the reaction vessel. The method further includes altering a chemical and/or thermodynamic equilibrium within the reaction vessel between the at least one oxidation zone and the at least one reduction zone by establishing at least one of an electrical current or an electrical potential via the at least one electrode. Altering the chemical and/or thermodynamic equilibrium within the reaction vessel may result in at least one of a substantially significant increase in a gasification reaction rate in the reaction vessel or a change in one or more gasification reaction products produced by the gasifier.

In yet another embodiment, a method for producing a gaseous product from a solid hydrocarbon-containing material is disclosed. The method includes providing a gasifier having at least one oxidation zone, at least one reduction zone, at least one electrode positioned in the at least one oxidation zone, and at least one electrode positioned in the at least one reduction zone and charging the reaction vessel with a hydrocarbon-containing material and initiating a gasification reaction in the reaction vessel. In at least a first stage of the gasification reaction, the method further includes altering a chemical and/or thermodynamic equilibrium in one or more redox reactions within the gasifier reaction vessel by at least one of: making the at least one oxidation zone more oxidizing by removing electrons from the at least one oxidation zone via the at least one electrode positioned therein, or making the at least one reduction zone more reducing by adding electrons to the at least one reduction zone via the at least one electrode positioned therein. Finally, the method includes generating a gaseous product that includes hydrogen, carbon monoxide, and methane.

Features from any of the disclosed embodiments may be used in combination with one another, without limitation. In addition, other features and advantages of the present disclosure will become apparent to those of ordinary skill in the art through consideration of the following detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating an updraft gasifier according to an embodiment.

FIG. 2 is a schematic diagram illustrating a downdraft gasifier according to an embodiment.

FIG. 3 is a diagram of an electrode system that may be used to alter the chemical and/or thermodynamic equilibrium in a gasifier according to an embodiment.

FIG. 4A is a schematic diagram showing a portion of a gasifier that includes electrodes positioned and configured to alter the chemical and/or thermodynamic equilibrium in a gasification reaction according to an embodiment.

FIG. 4B is a schematic diagram showing a portion of a gasifier that includes a plurality of rod-shaped electrodes positioned and configured to alter the chemical and/or thermodynamic equilibrium in a gasification reaction according to an embodiment.

FIG. 4C is a schematic diagram showing a portion of a gasifier that includes ring-shaped electrodes positioned and configured to alter the chemical and/or thermodynamic equilibrium in a gasification reaction according to an embodiment.

FIG. 5 is a waveform showing an illustrative waveform for driving the electrodes discussed herein according to an embodiment.

 DETAILED DESCRIPTION

Embodiments disclosed herein are related to gasifiers and methods for using such gasifiers for gasifying hydrocarbon-containing materials. The gasifiers disclosed herein include a gasification reaction vessel having one or more electrodes positioned therein. The one or more electrodes may be used to alter the chemical and/or thermodynamic equilibrium of the gasification reaction. For example, the one or more electrodes may be used to make the oxidation zone more oxidizing and/or to make the reduction zone more reducing such that oxidation and/or reduction reactions are favored. The one or more electrodes in such gasifiers may, for example, be used to alter the mix of reaction products produced by the gasification reaction, to lower the gasification reaction temperature, to enable altering the dimensions of the gasifier (e.g., to make the gasifier smaller) without sacrificing efficiency, to speed up startup and/or shutdown, or combinations thereof.

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Other embodiments may be used and/or other changes may be made without departing from the spirit or scope of the disclosure.

FIGS. 1 and 2 are schematic diagrams illustrating two basic types of gasifiers. FIG. 1 illustrates a schematic diagram of an updraft gasifier 100 and FIG. 2 a schematic diagram of a downdraft gasifier 200. The updraft gasifier 100 includes a reaction vessel 102, a fuel hopper 104 that is positioned at an upper region of the reaction vessel 102 for feeding fuel 106 into the reaction vessel 102. In the updraft gasifier 100, fuel 106 fed in through the fuel hopper 104 slowly sinks downwards by gravity as conversion of fuel conversion proceeds, eventually forming ash 114. The updraft gasifier 100 further includes one or more inlets 108 for feeding a gasification medium (e.g., a blend/mixture of air, steam, and supplemental oxygen) into the reaction vessel. The gasification medium passes through a grate 110 positioned below the fuel hopper 104 and above the inlet 108, and flows up through the fuel bed 106 and out the outlet 112. In an updraft gasifier, the gas flowing out of the outlet 112 includes syngas (e.g., H2, CO, CH4, etc.) in addition to the products of decomposition released by pyrolysis of the fuel and steam released as a result of fuel drying.

The downdraft gasifier 200 is similar to the updraft gasifier 100, except that, as the name suggests, the relative orientations of the inlet and outlet ports are reversed. The downdraft gasifier 200 includes a reaction vessel 202, a fuel hopper 204 that is positioned at an upper region of the reaction vessel 202 for feeding fuel 206 into the reaction vessel 202. As with the updraft gasifier 100, fuel 206 fed in through the fuel hopper 204 slowly sinks downwards by gravity as conversion of fuel conversion proceeds, eventually forming ash 214. The downdraft gasifier 200 includes one or more inlets 208 for feeding a gasification medium (e.g., a blend/mixture of air, steam, and supplemental oxygen) into the reaction vessel 202. The gasification medium passes down through the fuel bed 206 and through a grate 210 and out the outlet 212 positioned below the grate 210. The gas flowing out of the outlet 212 includes syngas (e.g., H2, CO, CH4, etc.). One difference between an updraft gasifier 100 and a downdraft gasifier 200 is that the syngas produced by the downdraft gasifier 200 does not tend to be as contaminated with the products of decomposition released by pyrolysis of the fuel and steam released as a result of fuel drying.

The gasifiers 100 and 200 include a number of distinct reaction zones in their fuel beds 106 and 206. The fuel beds 106 and 206 each include a drying zone 116 and 216 positioned proximate to the hopper 104 and 201, a pyrolysis zone 118 and 218, an oxidation zone 120 and 220 positioned above the grate 110 and 210, and a reduction zone 122 and 222 positioned above the grate 110 and 210.

In the drying zone 116 and 216, the fuel is dried at around 100° C. Typically the resulting steam is mixed into the gas flow and may be involved with subsequent chemical reactions, notably the water-gas reaction if the temperature is sufficiently high enough.

In the pyrolysis zone 118 and 218, the pyrolysis (or devolatilization) process occurs at around 200-300° C. Volatiles are released and char is produced, resulting in significant weight loss for the fuel (e.g., up to about 70% weight loss for coal). The process is dependent on the properties of the carbonaceous material and determines the structure and composition of the char, which will then undergo gasification reactions.

The oxidation zone 120 and 220 and the reduction zone 122 and 222 are where the important reactions of gasification occur. The major difference between combustion and gasification from the point of view of the chemistry involved is that combustion takes place under oxidizing conditions, while gasification occurs under reducing conditions without combustion substantially occurring. In the gasification process, a carbon-based feedstock, in the presence of steam and oxygen at high temperature and moderate pressure, is converted in the reaction vessel to synthesis gas (e.g., a mixture of carbon monoxide and hydrogen), which is generally referred to as syngas. The chemistry of gasification is quite complex and involves many chemical reactions, some of the more important of which occurring in the oxidation zone 120 and 220 and the reduction zone 122 and 222 are:


C+O2→CO2 ΔHr=−393.4 MJ/kmol  (1)


C+½O2→CO ΔHr=−111.4 MJ/kmol  (2)


C+H2O→H2+CO ΔHr=130.5 MJ/kmol  (3)


C+CO22CO ΔHr=170.7 MJ/kmol  (4)


CO+H2OH2+CO2 ΔHr=−40.2 MJ/kmol  (5)


C+2H2→CH4 ΔHr=−74.7 MJ/kmol  (6)

Reactions (1) and (2) are exothermic oxidation reactions and provide most of the energy required by the endothermic gasification reactions (i.e., reactions (3) and (4)). The oxidation reactions occur very rapidly, completely consuming all of the oxygen present in the gasifier, so that most of the gasifier operates under reducing conditions. Reaction (5) is known as the water-gas shift reaction, which in essence converts CO into H2. The water-gas shift reaction alters the H2/CO ratio in the final mixture but does not greatly impact the heating value of the synthesis gas, because the heats of combustion of H2 and CO are, on a molar basis, almost identical. Methane formation, Reaction (6), is favored by high pressures and low temperatures and is, thus, mainly important in lower temperature gasification systems. Methane formation is an exothermic reaction that does not consume oxygen and, therefore, increases the efficiency of gasification and the final heating value of the synthesis gas. Overall, about 70% of the fuel's heating value is associated with the CO and H2 in the gas, but this may be higher depending upon the gasifier type.

Depending on the gasifier technology employed and the operating conditions, significant quantities of H2O, CO2, and CH4 may be present in the synthesis gas, as well as a number of minor and trace components. Under the reducing conditions in the gasifier, most of the fuel's sulfur converts to hydrogen sulfide (H2S), but 3-10% converts to carbonyl sulfide (COS). Fuel-bound nitrogen generally converts to gaseous nitrogen (N2), but some ammonia (NH3) and a small amount of hydrogen cyanide (HCN) are also formed. Most of the chlorine in the fuel is converted to HCl with some chlorine present in the particulate phase. Trace elements, such as mercury and arsenic, are released during gasification and partition among the different phases, such as fly ash, bottom ash, slag, and product gas.

Many other reactions, besides those listed, occur. In the initial stages of gasification, the rising temperature of the feedstock initiates devolatilization of the feedstock and the breaking of weaker chemical bonds to yield tars, oils, phenols, and hydrocarbon gases. These products generally react further to form H2, CO, and CO2. The fixed carbon that remains after devolatilization reacts with oxygen, steam, CO2, and H2.

Embodiments disclosed herein are directed to gasifiers that include at least one electrode that may be used to change the chemical and/or thermodynamic equilibrium of one or more of the chemical reactions in one or more zones in the gasifier during the gasification process such that selected oxidation and/or reduction reactions may be favored. Suitable examples of gasifiers include the types illustrated in FIGS. 1 and 2, or any other suitable type of gasifier, such as fluidized bed reactors, entrained flow gasifiers, plasma gasifiers, free radical gasifiers, or another type known to those having ordinary skill in the art. In an embodiment, the gasifier includes a reaction vessel configured to gasify at least one hydrocarbon-containing feed material. The reaction vessel includes at least one oxidation zone and at least one reduction zone; at least one electrode is positioned in the reaction vessel (e.g., within the at least one oxidation zone and/or the at least one reduction zone). The at least one electrode may be positioned and configured to alter a chemical and/or thermodynamic equilibrium in one or more of the at least one oxidation zone or the at least one reduction zone.

In an embodiment, altering the chemical and/or thermodynamic equilibrium within the reaction vessel (i.e., in the gasification process) may result in a substantial increase in a gasification reaction rate in the reaction vessel. In other embodiments, altering the chemical and/or thermodynamic equilibrium in the reaction vessel may result in a change in one or more gasification reaction products produced by the gasifier. For example, the mix of H2 and CO may be altered by changing the chemical and/or thermodynamic equilibrium to favor production of H2 and CO, and/or, in some embodiments, production of CH4 may be favored. Likewise, altering the chemical and/or thermodynamic equilibrium of one or more of the chemical reactions in the reaction vessel may be used to, for example, reduce startup or shutdown time for a gasification reaction in the reaction vessel.

In an embodiment, the chemical and/or thermodynamic equilibrium within the reaction vessel may be changed by selectively increasing the concentration of electrons in one or more zones of the reaction vessel and/or by selectively reducing the concentration of electrons in one or more zones of the reaction vessel. An embodiment of an electrode system 300 that may be used to change the chemical and/or thermodynamic equilibrium in a gasifier reaction vessel is illustrated in FIG. 3. The electrode system 300 includes a first electrode 310 and a second electrode 320. Electrodes 310 and 320 may be operably coupled to a power supply 330 via electrical connectors 340 and 350. The system may also include a ground 360. The ground may, for example, be electrically connected to the body of the gasifier.

In an embodiment, the electrode system 300 may be configured to alter the chemical and/or thermodynamic equilibrium in a gasification reaction by setting up an electron current within or between selected zones within the reaction vessel. For example, electrons may be produced in oxidation reaction and consumed in reduction reactions. An oxidizing zone may be made more oxidizing (i.e., oxidation reactions may be thermodynamically favored) by removing product electrons from the oxidizing zone. Likewise, a reduction zone may be made more reducing (i.e., reducing reactions may be thermodynamically favored) by adding excess reactant electrons to the reduction zone.

In the illustrated embodiment, the first electrode 310 may be positively charged and the second electrode may be negatively charged. Accordingly, the first electrode may be used to increase the concentration of electrons 305 in a selected zone of the gasifier by, for example, attracting electrons produced in the redox gasification reaction(s) towards the positively charged electrode 310. Likewise, the second electrode 320 may be used to decrease the concentration of electrons 310 in another zone of the gasifier by, for example, repelling electrons produced in the redox gasification reaction(s) from the negatively charged electrode 320. Likewise, electrode 320 may be used to attract a counter current of positively charged species (not shown). In other embodiments, the first and second electrodes 310 and 320 may be charged oppositely to what is illustrated in FIG. 3, or electrodes 310 and 320 may be charged the same (either both positive or both negative). In addition, as will be explained in greater detail below, the power supply 330 may be an alternating power supply that may be configured to switch the polarity of the first and second electrodes 310 and 320 at a selected rate.

In addition to the foregoing, the electrode system 300 may be configured to alter the chemical and/or thermodynamic equilibrium in a gasification reaction by directly injecting electrons into the gasifier. That is, given the right conditions, (e.g., high electrical potential and high temperature (e.g., about 1000° C. or greater)), the negatively charged electrode may be configured to stream electrons into the reaction vessel via a process called thermionic emission.

Referring now to FIG. 4A, a cutaway view of a portion of a gasifier 400a that includes an electrode system is illustrated. The gasifier 400a includes a reaction vessel 402a, a reduction zone 420, and an oxidation zone 422. It should be appreciated, however, that the relative arrangement of the oxidation and reduction zones is illustrated for reference purposes only. Depending on the type of gasifier, the relative arrangement of the oxidation and reduction zones may, for example, be reversed, or the gasifier may have more than one oxidation zone or more than one reduction zone.

The electrode system includes at least a first electrode 430a and a second electrode 440a. The first and second electrodes 430a and 440a are connected to an electrical power supply 450 via connectors 460 and 480, respectively. The electrode system also includes a ground 470, which, in the illustrated embodiment, is connected to the reaction vessel 402a.

As discussed in greater detail above, the at least first and second electrodes 430a and 440a may be used to alter the chemical and/or thermodynamic equilibrium in the reaction vessel 402a by selectively enriching or depleting the population of electrons in one or more portions of the reaction vessel 402a. In an embodiment, the oxidation zone 422 may be made more oxidizing by removing electrons from the oxidation zone 422, and the reduction zone 420 may be made more reducing by adding electrons to the reduction zone 420.

Referring now to FIG. 4B, a cutaway view of a portion of a gasifier 400b that includes an electrode system is illustrated. The gasifier 400b includes a reaction vessel 402b, a reduction zone 420, and an oxidation zone 422. It should be appreciated, however, that the relative arrangement of the oxidation and reduction zones is illustrated for reference purposes only. Depending on the type of gasifier, the relative arrangement of the oxidation and reduction zones may, for example, be reversed, or the gasifier may have more than one oxidation zone or more than one reduction zone.

The electrode system includes at least a first series of rod-shaped electrodes 430b and at least a second series of rod-shaped electrodes 440b. The first and second series of rod-shaped electrodes 430b and 440b are connected to an electrical power supply 450 via connectors 460 and 480, respectively. The electrode system also includes a ground 470, which, in the illustrated embodiment, is connected to the reaction vessel 402b or other grounding feature.

The first and second series of rod-shaped electrodes 430b and 440b may be used to alter the chemical and/or thermodynamic equilibrium in the gasification reaction in the reaction vessel 402b by selectively enriching or depleting the population of electrons in one or more portions of the reaction vessel 402b. In an embodiment, the oxidation zone 422 may be made more oxidizing by using the rod-shaped electrodes 430b to remove electrons from the oxidation zone 422, and the reduction zone 420 may be made more reducing using the rod-shaped electrodes 440b to add electrons to the reduction zone 420. The foregoing assumes that substantially all of the first series of rod-shaped electrodes 430b are charged differently that the second series of rod-shaped electrodes 440b. However, in an embodiment, the charging of the first and second series of rod-shaped electrodes 430b and 440b may be mixed such that, for example, at least some of the first series of rod-shaped electrodes 430b are positively charged and some are negatively charged and, likewise, at least some of the second series of rod-shaped electrodes 440b are positively charged and some are negatively charged. Such an arrangement may, for example, be used to finely tune the oxidation and reduction potentials in the reduction zone 420 and the oxidation zone 422.

Referring now to FIG. 4C, an isometric view of a gasifier 400c that includes an electrode system is illustrated. The gasifier 400c includes a reaction vessel 402c, a reduction zone 420, and an oxidation zone 422. It should be appreciated, however, that the relative arrangement of the oxidation and reduction zones is illustrated for reference purposes only. Depending on the type of gasifier, the relative arrangement of the oxidation and reduction zones may, for example, be reversed, or the gasifier may have more than one oxidation zone or more than one reduction zone.

The electrode system includes at least a pair of spatially separated ring-shaped electrodes 430c and 440c. In the illustrated embodiment, a first ring-shaped electrode 430c is positioned in the oxidation zone 422 and a second ring-shaped electrode 440c is positioned in the reduction zone 420. The spatially separated ring-shaped electrodes 430c and 440c are connected to an electrical power supply 450 via connectors 460 and 480, respectively. The electrode system also includes a ground 470, which, in the illustrated embodiment, is connected to the reaction vessel 402c.

The spatially separated ring-shaped electrodes 430c and 440c may be used to alter the chemical and/or thermodynamic equilibrium in the reaction vessel 402c by selectively enriching or depleting the population of electrons in one or more portions of the reaction vessel 402c. In an embodiment, the oxidation zone 422 may be made more oxidizing by using the ring-shaped electrode 430c to remove electrons from the oxidation zone 422, and the reduction zone 420 may be made more reducing using the rod-shaped electrodes 440c to add electrons to the reduction zone 420.

Because the oxidation zone 422 may be made more oxidizing and the reduction zone 420 may be made more reducing, it may be possible to, for example, make the gasifier 402a, 402b, or 402c smaller and/or to increase throughput without significantly altering or increasing the energy input(s). Likewise, increasing the reactivity in the reduction and oxidation zones 420 and 422 may shorten the startup time for the gasifier 402a, 402b, or 402c and shorten lag period for the production of syngas.

In another embodiment, the oxidation zone 422 may be made less oxidizing by adding electrons to the oxidation zone 422, and/or the reduction zone 420 may be made less reducing by removing electrons from the reduction zone 420. This may, for example, shorten the shutdown time if the gasifier 402a, 402b, or 402c is taken offline for maintenance.

Referring now to FIG. 5, a waveform showing an example of an alternating voltage waveform for driving the electrodes discussed herein is illustrated. Applying a time varying voltage waveform via the power source 330 or 450 generates a time varying electric field in the gasifier 402a, 402b, or 402c that, depending on the shape and period of the waveform, may be effective for fine-tuning the chemical and/or thermodynamic equilibrium in one or more regions of the gasifier 402a, 402b, or 402c. For example, the time varying waveform may generate a time varying electric field effective to repel or attract charged chemical species of different polarity during a gasification reaction. For example, FIG. 3 illustrates that when the electrode 320 is negatively charged by application of a VL voltage over time frame tL, as shown in the time varying voltage waveform 502 shown in FIG. 5, negatively charged species (e.g., electrons) may be produced from the electrode 320. Alternatively, positively charged chemical species (not shown) (e.g., fuel fragments, positively charged ions, etc.) may be electrostatically attracted to the electrode 320 and negatively charged chemical species and electrons 315 are electrostatically repelled from the electrode 320. Likewise, FIG. 3 illustrates that when the electrode 310 is positively charged by application of a VH voltage over time frame tH as shown in the time varying voltage waveform 502 shown in FIG. 5, negatively charged chemical species 305 (e.g., electrons, negatively charged ions, etc.) are electrostatically attracted to the electrode 310 and positively charged chemical species (not shown) are electrostatically repelled from the electrode 310. Thus, over one or more cycles P1 of the time varying voltage waveform 502, the concentration of negatively and positively charged chemical species and electrons introduced and/or generated during the gasification process may be selectively biased in the gasifier 402a, 402b, or 402c.

It should be noted that the time varying voltage waveform 502 shown in FIG. 5 is only one embodiment of a suitable time varying voltage waveform. Other suitable time varying voltage waveforms include a sine waveform, a convoluted waveform function, an arbitrary waveform function, or a pulsed waveform.

In an embodiment, a method of gasifying a hydrocarbon-containing material is disclosed. The method includes providing a gasifier that includes a reaction vessel having at least one oxidation zone, at least one reduction zone, and at least one electrode positioned in the reaction vessel and charging the reaction vessel with a hydrocarbon-containing material and initiating a gasification reaction in the reaction vessel. The method further includes altering a chemical and/or thermodynamic equilibrium within the reaction vessel between the at least one oxidation zone and the at least one reduction zone by establishing at least one of an electrical current or an electrical potential via the at least one electrode. Altering the chemical and/or thermodynamic equilibrium within the reaction vessel may result in at least one of a substantially significant increase in a gasification reaction rate in the reaction vessel or a change in one or more gasification reaction products produced by the gasifier.

In another embodiment, a method for producing a gaseous product from a solid hydrocarbon-containing material is disclosed. The method includes providing a gasifier having at least one oxidation zone, at least one reduction zone, at least one electrode positioned in the at least one oxidation zone, and at least one electrode positioned in the at least one reduction zone and charging the reaction vessel with a hydrocarbon-containing material and initiating a gasification reaction in the reaction vessel. In at least a first stage of the gasification reaction, the method further includes altering a chemical and/or thermodynamic equilibrium in one or more redox reactions within the gasifier reaction vessel by at least one of: making the at least one oxidation zone more oxidizing by removing electrons from the at least one oxidation zone via the at least one electrode positioned therein, or making the at least one reduction zone more reducing by adding electrons to the at least one reduction zone via the at least one electrode positioned therein. Finally, the method includes generating a gaseous product that includes hydrogen, carbon monoxide, and methane.

In an embodiment of the methods described herein, the at least one electrode includes at least one electrode positioned in the at least one oxidation zone and at least one electrode positioned in the reduction zone. The methods further include at least one of: removing electrons from the at least one oxidation zone, or adding electrons into the at least one reduction zone.

In an embodiment of the methods described herein, altering the chemical and/or thermodynamic equilibrium in one or more redox reactions within the gasifier reaction vessel results in at least one of: a substantially significant increase in a gasification reaction rate in the reaction vessel; a reduction in the temperature of the gasification reaction; an efficiency increase in the gasification reaction; or a change in the gaseous product production by the gasifier.

In an embodiment of the methods described herein, the gasification reaction includes a first stage and at least a second stage. In the at least second stage of the gasification reaction, the method further includes at least one of: decreasing the oxidation potential of the at least one oxidation zone by adding electrons to the at least one oxidation zone via the at least one electrode positioned therein; or decreasing the reduction potential of the at least one reduction zone by removing electrons from the at least one reduction zone via the at least one electrode positioned therein. Making the gasifier reaction vessel at least one of less oxidizing or less reducing may, for example, be used to change the mix of products (e.g., increasing CH4 and reducing H and CO) produced from the gasification reaction and/or may be used to speed shutdown of the gasifier if the gasifier needs to be taken offline for repairs or maintenance.

In one embodiment, the methods described herein further include electrically connecting the at least one electrode positioned in the at least one oxidation zone and the at least one electrode positioned in the reduction zone to an alternating power source, and establishing an alternating current between the at least one oxidation zone and the at least one reduction zone.

In an embodiment, the alternating current has a characteristic frequency selected to result in at least one of: a substantially significant increase in a gasification reaction rate in the reaction vessel; a reduction in the temperature of the gasification reaction; an efficiency increase in the gasification reaction; or a change in the gaseous product production by the gasifier.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting.

Claims

1. A gasifier, comprising

a reaction vessel configured to gasify at least one hydrocarbon-containing feed material, wherein the reaction vessel includes at least one oxidation zone and at least one reduction zone;
an electrical power source; and
at least one electrode positioned in the reaction vessel and being operably coupled to the electrical power source;
wherein the electrical power source and the at least one electrode are configured to alter a chemical and/or thermodynamic equilibrium in one or more of the at least one oxidation zone or the at least one reduction zone.

2. The gasifier of claim 1 wherein the electrical power source and the at least one electrode are configured to alter the chemical and/or thermodynamic equilibrium by making at least one of the at least one oxidation zone more oxidizing or more reducing or make the at least one reduction zone more reducing or more oxidizing.

3. The gasifier of claim 1 wherein altering the chemical and/or thermodynamic equilibrium in one or more of the at least one oxidation zone or the at least one reduction zone results in a substantial increase in a gasification reaction rate in the reaction vessel.

4. The gasifier of claim 1 wherein altering the chemical and/or thermodynamic equilibrium in one or more of the at least one oxidation zone or the at least one reduction zone alters one or more gasification reaction products produced by the gasifier.

5. The gasifier of claim 1 wherein the at least one electrode is positioned in the at least one oxidation zone, and the electrical power source and the at least one electrode are configured to make the at least one oxidation zone more oxidizing.

6. The gasifier of claim 5 wherein the at least one electrode positioned in the at least one oxidation zone is configured to remove electrons from the at least one oxidation zone.

7. The gasifier of claim 1 wherein the at least one electrode is positioned in the at least one reduction zone, and the electrical power source and the at least one electrode are configured to make the at least one reduction zone more reducing.

8. The gasifier of claim 7 wherein the at least one electrode positioned in the at least one reduction zone is configured to add electrons to the at least one reduction zone.

9. The gasifier of claim 1 wherein the electrical power source and at least one electrode re configured to cause electrical current flow between the at least one oxidation zone and the at least one reduction zone.

10. The gasifier of claim 1 wherein the at least one electrode includes at least one first electrode positioned in the at least one oxidation zone and at least one second electrode positioned in the reduction zone, wherein the electrical power source and the first and second electrodes are configured to add electrons to the at least one oxidation zone and remove electrons from the at least one reduction zone.

11. The gasifier of claim 1 wherein the at least one electrode includes a first electrode positioned in the at least one oxidation zone and a second electrode positioned in the reduction zone, wherein the first and second electrodes are operably coupled to the electrical power source and configured to establish an alternating electrical current between the at least one oxidation zone and the at least one reduction zone.

12. A method of gasifying a hydrocarbon-containing material, comprising:

providing a gasifier that includes a reaction vessel having at least one oxidation zone, at least one reduction zone, and at least one electrode positioned in the reaction vessel, the at least one electrode being operably coupled to an electrical power source;
charging the reaction vessel with a hydrocarbon-containing material and initiating a gasification reaction in the reaction vessel; and
altering a chemical and/or thermodynamic equilibrium within the reaction vessel between the at least one oxidation zone and the at least one reduction zone by establishing at least one of an electrical current or an electrical potential via the at least one electrode;
wherein altering the chemical and/or thermodynamic equilibrium within the reaction vessel results in at least one of a substantially significant increase in a gasification reaction rate in the reaction vessel or a change in one or more gasification reaction products produced by the gasifier.

13. The method of claim 12 wherein the at least one electrode includes at least one electrode positioned in the at least one oxidation zone and at least one electrode positioned in the reduction zone, the method further comprising at least one of:

removing electrons from the at least one oxidation zone; or
adding electrons into the at least one reduction zone.

14. The method of claim 12, further comprising:

electrically connecting the at least one electrode positioned in the at least one oxidation zone and the at least one electrode positioned in the reduction zone to an electrical power source; and
establishing an alternating current between the at least one oxidation zone and the at least one reduction zone.

15. The method of claim 12, further comprising making the at least one oxidation zone more oxidizing by removing electrons therefrom.

16. The method of claim 12, further comprising increasing the reduction potential of the at least one reduction zone by adding electrons thereto.

17. The method of claim 12 wherein the at least one electrode includes at least one first electrode positioned in the at least one oxidation zone and at least one second electrode positioned in the reduction zone, the method further comprising at least one of:

adding electrons into the at least one oxidation zone; or
removing electrons from the at least one reduction zone.

18. A method for producing a gaseous product from a solid hydrocarbon-containing material, comprising:

providing a gasifier having at least one oxidation zone, at least one reduction zone, at least one electrode positioned in the at least one oxidation zone, and at least one electrode positioned in the at least one reduction zone, the at least one electrode being operably coupled to an electrical power source;
charging the reaction vessel with a hydrocarbon-containing material and initiating a gasification reaction in the reaction vessel;
in at least a first stage of the gasification reaction, altering a chemical and/or thermodynamic equilibrium in one or more redox reactions within the gasifier reaction vessel by at least one of: making the at least one oxidation zone more oxidizing by removing electrons from the at least one oxidation zone via the at least one electrode positioned therein; or making the at least one reduction zone more reducing by adding electrons to the at least one reduction zone via the at least one electrode positioned therein; and
generating a gaseous product that includes hydrogen, carbon monoxide, and methane.

19. The method of claim 18, wherein altering the chemical and/or thermodynamic equilibrium in one or more redox reactions within the gasifier reaction vessel results in at least one of:

a substantially significant increase in a gasification reaction rate in the reaction vessel;
a reduction in the temperature of the gasification reaction;
an efficiency increase in the gasification reaction; or
a change in the gaseous product production by the gasifier.

20. The method of claim 18, in at least a second stage of the gasification reaction, the method further comprising at least one of:

making the at least one oxidation zone less oxidizing by adding electrons to the at least one oxidation zone via the at least one electrode positioned therein; or
making the at least one reduction zone less reducing by removing electrons from the at least one reduction zone via the at least one electrode positioned therein.

21. The method of claim 18, in at least a second stage of the gasification reaction, the method further comprising:

electrically connecting the at least one electrode positioned in the at least one oxidation zone and the at least one electrode positioned in the at least one reduction zone to a power supply; and
establishing an alternating current between the at least one oxidation zone and the at least one reduction zone.

22. The method of claim 21, wherein the alternating current has a characteristic frequency selected to result in at least one of:

a substantially significant increase in a gasification reaction rate in the reaction vessel;
a reduction in the temperature of the gasification reaction;
an efficiency increase in the gasification reaction; or
a change in the gaseous product production by the gasifier.
Patent History
Publication number: 20140196368
Type: Application
Filed: Jan 13, 2014
Publication Date: Jul 17, 2014
Applicant: ClearSign Combustion Corporation (Seattle, WA)
Inventor: Christopher A. Wiklof (Everett, WA)
Application Number: 14/153,665
Classifications
Current U.S. Class: Retort (48/89); 48/197.0FM
International Classification: C10J 3/72 (20060101);