WO2007141350A1 - Procedure and reactor for the reformation of fuels - Google Patents

Procedure and reactor for the reformation of fuels Download PDF

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Publication number
WO2007141350A1
WO2007141350A1 PCT/ES2007/000214 ES2007000214W WO2007141350A1 WO 2007141350 A1 WO2007141350 A1 WO 2007141350A1 ES 2007000214 W ES2007000214 W ES 2007000214W WO 2007141350 A1 WO2007141350 A1 WO 2007141350A1
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Prior art keywords
reforming
reactor
fuels
fuel
barrier discharge
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PCT/ES2007/000214
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Spanish (es)
French (fr)
Inventor
Victor Rico Gaviria
José COTRINO BAUTISTA
Agustín Rodriguez Gonzalez-Elipe
Carmen Lopez Santos
Javier Brey Sanchez
Belén SARMIENTO MARRON
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Hynergreen Technologies, S.A.
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Publication of WO2007141350A1 publication Critical patent/WO2007141350A1/en

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/2406—Generating plasma using dielectric barrier discharges, i.e. with a dielectric interposed between the electrodes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J19/087—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J19/088—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
    • C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
    • C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
    • C01B3/342—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents with the aid of electrical means, electromagnetic or mechanical vibrations, or particle radiations
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/2406—Generating plasma using dielectric barrier discharges, i.e. with a dielectric interposed between the electrodes
    • H05H1/2443—Generating plasma using dielectric barrier discharges, i.e. with a dielectric interposed between the electrodes the plasma fluid flowing through a dielectric tube
    • H05H1/246—Generating plasma using dielectric barrier discharges, i.e. with a dielectric interposed between the electrodes the plasma fluid flowing through a dielectric tube the plasma being activated using external electrodes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B01J2219/0807—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes
    • B01J2219/0824—Details relating to the shape of the electrodes
    • B01J2219/0826—Details relating to the shape of the electrodes essentially linear
    • B01J2219/083—Details relating to the shape of the electrodes essentially linear cylindrical
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0873—Materials to be treated
    • B01J2219/0875—Gas
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0894—Processes carried out in the presence of a plasma
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/02—Processes for making hydrogen or synthesis gas
    • C01B2203/0205—Processes for making hydrogen or synthesis gas containing a reforming step
    • C01B2203/0211—Processes for making hydrogen or synthesis gas containing a reforming step containing a non-catalytic reforming step
    • C01B2203/0216—Processes for making hydrogen or synthesis gas containing a reforming step containing a non-catalytic reforming step containing a non-catalytic steam reforming step
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/02—Processes for making hydrogen or synthesis gas
    • C01B2203/0205—Processes for making hydrogen or synthesis gas containing a reforming step
    • C01B2203/0211—Processes for making hydrogen or synthesis gas containing a reforming step containing a non-catalytic reforming step
    • C01B2203/0222—Processes for making hydrogen or synthesis gas containing a reforming step containing a non-catalytic reforming step containing a non-catalytic carbon dioxide reforming step
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/08—Methods of heating or cooling
    • C01B2203/0805—Methods of heating the process for making hydrogen or synthesis gas
    • C01B2203/0861—Methods of heating the process for making hydrogen or synthesis gas by plasma
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H2245/00—Applications of plasma devices
    • H05H2245/10—Treatment of gases
    • H05H2245/17—Exhaust gases

Definitions

  • the object of the present invention is a process and a reactor for reforming liquid or gaseous fuels and their transformation into H 2 and CO from mixtures thereof with water vapor and / or CO 2 .
  • This procedure is based on the use of cold plasma technology and, in particular, on the use of barrier-type discharges in a cylindrical reactor where the control of the surface roughness of one of the electrodes is a determining factor in the efficiency of the process .
  • the mixtures of the fuel and other gas (CO 2 or H 2 O) are passed through the reactor at room temperature (or heated above 100 0 C in the case of water) to proceed with its activation and conversion into the mixture desired end STATE OF THE TECHNIQUE
  • Another plasma technology widely used to carry out reforming processes with hydrocarbons or alcohols is based on barrier discharge processes, in which the plasma is generated by high-voltage AC discharges (generally between 5 and 30 kV) and frequencies in the kHz range (Eliasson B., IEEE Transactions on Plasma Science, 19, 1063-1077 (1991); Hammer T., Contributions to Plasma Physics, 39, 441-462
  • one of the electrodes of the system is activated by high-voltage AC discharge, while the other is usually grounded (Ulrich Kogelschatz, Dielectric-Barrier Discharges: Their History, Discharge Physics, and Industrial Applications, Plasma Chemistry and Plasma Processing , Volume 23, Number 1, March 2003 pages 1-46).
  • One of the differential characteristics of the process of the invention has to do with how to apply the external voltage.
  • Another characteristic element present in one of the existing patents on DBD reactors, is the use of a porous metal as an active electrode, through whose pores the gas or mixture of gases used circulates.
  • Electrode internal cylinder
  • Electrode exital metallic layer
  • Tube of dielectric material Figure 2. General scheme of the reaction system 1.- Lines of conduction of gases / vapors of entrance and exit heated
  • the present invention relates to a process for reforming gaseous fuels or vaporable liquids, in a plasma barrier discharge reactor comprising the following steps: a) the introduction of a vapor or gas mixture between the fuel and CO2 and / or H2O, in proportions between 1: 1 and 1:10 in the barrier discharge reactor for continuous treatment and at atmospheric pressure. b) adjustment in the reactor of the discharge conditions, particularly the high voltage value and frequency, as well as temperature conditions, c) the activation of the reactor once the conditions in the previous stage have been adjusted.
  • the discharge is performed by supplying a high voltage AC potential between preferably 0.5 and 80 kV, more preferably between 15 and 30 kV and a frequency between preferably 50 Hz and 70 kHz, more preferably between 3 and 15 kHz, applied between the two Barrier discharge reactor electrodes changing polarity alternately, without any of those electrodes being grounded at any time.
  • a fuel / C0 2 mixture is introduced, a proportion between preferably I and 10 is used.
  • a fuel / H 2 mixture is introduced, a proportion preferably between 1 and 10 is also used.
  • the ratio is preferably between 1: 0.5: 0.5 and 1: 5: 5.
  • the flow of the reaction mixture is between 1 and 100 standard cubic centimeters per minute (sccm) depending on the size of the reactor, and the fuels used are preferably hydrocarbons, alcohols, natural gas or mixtures thereof, more preferably commercial fuels in the form of volatile fluids such as gasoline or gas-oil.
  • the products obtained by the reforming process object of the present invention have a hydrocarbon content of less than 1% and a CO + H2 content corresponding to methane conversions of up to 95%.
  • a barrier discharge plasma reactor for reforming fuels comprising the following elements: a) a power supply that supplies a high voltage alternating current, between 0.5 and 80 kV, preferably between 15 and 30 kV, and with a frequency between 50 Hz and 70 kHz, preferably between 3 and 15 kHz; b) a cylindrical steel electrode that incorporates a metal sheet outside and connected to a high voltage power supply; and c) a cylindrical geometry dielectric device placed concentrically outside the cylindrical electrode.
  • the surface of the steel electrode preferably has a surface roughness characterized by rough motifs of size between 1 and 10 ⁇ m and the distance between the cylindrical steel electrode and the dielectric device, corresponding to the discharge zone is between 1 and 10 mm, preferably between 1 and 3 mm.
  • the dielectric device is constructed in quartz, alumina or ceramic and has a thickness between 1 and 10 mm.
  • the reactor has dimensions between 8 and 40 cm long and between 1.5 and 20 era in diameter.
  • the reactor includes control elements the temperature of the reaction zone, which allow regulation between room temperature and 500 0 C.
  • the power supply does not work between one active electrode and another to ground, but instead operates by applying the high voltage alternately between the two electrodes which, in this way, both act as active electrodes.
  • the source of potential built and constituting an inseparable part of the reactor for the realization of the reforming process is an alternating current source with a variable frequency preferably between 50 Hz and 70 kHz, more preferably between 3 and 15 kHz, and which supplies voltages peak to peak preferably between 0.5 and 80 kV, more preferably between 15 and 30 kV.
  • the reactor is integrated into a general reaction system where it is possible to dose controlled quantities of the reagents (Figure 2). Both reagent feed and product outlet tubes can be heated to controlled temperatures above 100 ° C. It is necessary to proceed to this heating in the case of using water and / or liquid fuels that it is necessary to vaporize before feeding the mixture into the reactor.
  • Gas flow control can be done by flow controllers (gases) or liquid flow control systems in the reactor feed tube system.
  • the control of the exhaust gases can be done by means of an analysis system directly connected to the outlet gas tube.
  • the reactor is formed by a steel cylinder, whose external surface in the discharge zone has been subjected to a controlled abrasion process to produce a rough surface of defined characteristics.
  • the cylinder is connected to the source's high voltage supply and a steel feeding tube. To prevent the entire supply pipe system from being electrically activated through this tube, it is electrically isolated from the pipes, coupling a glass tube or other dielectric material in an intermediate zone.
  • the steel cylinder is placed concentric to a tube of a dielectric material (quartz, alumina or any other ceramic) of thickness between 1 and 10 ⁇ un, so that the reaction mixture circulates between the steel cylinder and the ceramic tube.
  • the distance between the two is another one of the Critical process parameters and may vary between 1 and 10 mm.
  • a sheet of metal is placed that acts as the other active electrode in the process.
  • the plasma in the circulation zone of the gas mixture is formed coinciding with the surface of the metal cylinder that has the metal layer wound, and can therefore be varied at will.
  • the entire assembly is surrounded by a small oven to keep the assembly above 100 ° C in case H 2 O and / or liquid fuels are used in the reaction mixture.
  • the entire previous reaction system can be integrated into a protective and insulating housing if deemed necessary.
  • the reactor has characteristic dimensions between 8 and 40 cm long and between 1.5 and 20 cm in diameter.
  • the reactions that can be activated by the developed reactor can be schematized according to:
  • C n H m may indicate a hydrocarbon, mixtures of hydrocarbons, an alcohol or mixtures of alloys and / or hydrocarbons.
  • the refurbishment of the selected fuel (s) can be carried out by changing different process variables, such as the voltage and frequency of the discharge, the reactor temperature, the total flow from the reaction mixture or the ratio between the hydrocarbon / alcohol and the other reagent selected (H 2 O or CO 2 ).
  • process variables such as the voltage and frequency of the discharge, the reactor temperature, the total flow from the reaction mixture or the ratio between the hydrocarbon / alcohol and the other reagent selected (H 2 O or CO 2 ).
  • H 2 O or CO 2 the direct dissociation of the hydrocarbon into C (solid) and H 2 can also be induced.
  • the temperature is also a parameter of great importance that, for values above 120 ° C, influences reducing the reaction yield.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Toxicology (AREA)
  • Combustion & Propulsion (AREA)
  • Inorganic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Electromagnetism (AREA)
  • Fluid Mechanics (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Hydrogen, Water And Hydrids (AREA)

Abstract

The present invention relates to a procedure for the reformation of gaseous or liquid fuels in mixtures with water and/or CO2 in a dielectric barrier discharge (DBD) plasma reactor. It is differentiated from other reformation procedures based on plasma techniques in that the design and characteristics of the reactor are conducive to having virtually the entire process lead to the production of mixtures of carbon monoxide and hydrogen, with virtually no contribution from higher hydrocarbons. This process takes place at low temperatures and has low electrical power consumption requirements. Furthermore, the present invention relates to a barrier discharge plasma reactor for the reformation of fuels comprising a power supply source, a cylindrical electrode and a dielectric device.

Description

TITULOTITLE
PROCEDIMIENTO Y REACTOR PARA EL REFORMADO DE COMBUSTIBLESPROCEDURE AND REACTOR FOR REFORMING FUELS
CAMPO TÉCNICO DE LA INVENCIÓN El sector de aplicación de la presente invención se enmarca, dentro del campo de nuevas tecnologías para el sector energético y el de las tecnologías químicas, en el desarrollo de procedimientos de conversión de combustibles líquidos o gases en hidrógeno y/o de preparación de mezclas "syngas" (mezclas CO más H2) • Una de las aplicaciones potenciales de la tecnología se relaciona con su uso como fuente primaria de hidrógeno para alimentar pilas de combustible u otros procesos de transformación de energía química en mecánica (motores) y/o eléctrica. Otra aplicación seria como generador de "syngas" para fines sintéticos.TECHNICAL FIELD OF THE INVENTION The application sector of the present invention is framed, within the field of new technologies for the energy sector and that of chemical technologies, in the development of procedures for converting liquid fuels or gases into hydrogen and / or of preparation of "syngas" mixtures (CO mixtures plus H 2 ) • One of the potential applications of the technology is related to its use as a primary source of hydrogen to fuel fuel cells or other processes of transformation of chemical energy into mechanics (engines ) and / or electric. Another application would be as a generator of "syngas" for synthetic purposes.
OBJETO DE LA INVENCIÓNOBJECT OF THE INVENTION
El objeto de la presente invención es un procedimiento y un reactor para el reformado de combustibles líquidos o gaseosos y su transformación en H2 y CO a partir de mezclas de los mismos con vapor de agua y/o CO2. Este procedimiento se basa en la utilización de la tecnología de plasmas frios y, en concreto, en la utilización de descargas tipo barrera en un reactor cilindrico donde el control de la rugosidad superficial de uno de los electrodos es un factor determinante de la eficacia del proceso. Las mezclas del combustible y del otro gas (CO2 o H2O) se hacen pasar por el reactor a temperatura ambiente (o calentadas por encima de 100 0C en el caso del agua) para proceder a su activación y conversión en la mezcla final deseada. ESTADO DE LA TÉCNICAThe object of the present invention is a process and a reactor for reforming liquid or gaseous fuels and their transformation into H 2 and CO from mixtures thereof with water vapor and / or CO 2 . This procedure is based on the use of cold plasma technology and, in particular, on the use of barrier-type discharges in a cylindrical reactor where the control of the surface roughness of one of the electrodes is a determining factor in the efficiency of the process . The mixtures of the fuel and other gas (CO 2 or H 2 O) are passed through the reactor at room temperature (or heated above 100 0 C in the case of water) to proceed with its activation and conversion into the mixture desired end STATE OF THE TECHNIQUE
Los métodos de reformado de hidrocarburos más clásicos se basan en el uso de catalizadores y transcurren a temperaturas elevadas (Catalyst for hydrocarbon reforming reaction: United States Patent 6852668) . Más recientemente se ha propuesto el uso de procesos de reformado usando plasmas. Estos métodos tienen como ventajas el que pueden llevarse a cabo a más bajas temperaturas, virtualmente a temperatura ambiente y que requieren tiempos de estabilización muy cortos. Se ha propuesto el uso de diversas fuentes de excitación, incluyéndose entre los más comunes los procesos de reformado usando fuentes de microondas (Maxim Deminsky, Victor Jivotov, Boris Potapkin, and Vladimir Rusanov, Plasma-assisted production of hydrogen from hydrocarbons, Puré Appl. Chem. , VoI. 74, No. 3, pp. 413-418, 2002.) o descargas barreras (DBD) (Kogelschatz U., Plasma Chemistry and Plasma Processing, 18, 375-393 (1998)). En el primer caso, existen procesos que se realizan a presiones por debajo de la atmosférica y otros donde los reactores correspondientes actúan a presión atmosférica. En ambos casos no es infrecuente que, los productos de reacción incluyan hidrocarburos superiores fruto de procesos no controlados de dimerización de hidrocarburos. Otra tecnologia de plasma bastante utilizada para la realización de procesos de reformado con hidrocarburos u alcoholes es la basada en procesos de descarga barrera, en los cuales el plasma se genera mediante descargas AC de alto voltaje (entre 5 y 30 kV generalmente) y frecuencias en el rango de los kHz (Eliasson B., IEEE Transactions on Plasma Science, 19, 1063-1077 (1991); Hammer T., Contributions to Plasma Physics, 39, 441-462The most classical hydrocarbon reforming methods are based on the use of catalysts and run at elevated temperatures (Catalyst for hydrocarbon reforming reaction: United States Patent 6852668). More recently, the use of reforming processes using plasmas has been proposed. These methods have the advantages that they can be carried out at lower temperatures, virtually at room temperature and that require very short stabilization times. The use of various sources of excitation has been proposed, including among the most common the processes of reforming using microwave sources (Maxim Deminsky, Victor Jivotov, Boris Potapkin, and Vladimir Rusanov, Plasma-assisted production of hydrogen from hydrocarbons, Puré Appl. Chem., VoI. 74, No. 3, pp. 413-418, 2002.) or discharge barriers (DBD) (Kogelschatz U., Plasma Chemistry and Plasma Processing, 18, 375-393 (1998)). In the first case, there are processes that are carried out at pressures below atmospheric and others where the corresponding reactors act at atmospheric pressure. In both cases it is not uncommon for the reaction products to include higher hydrocarbons, the result of uncontrolled hydrocarbon dimerization processes. Another plasma technology widely used to carry out reforming processes with hydrocarbons or alcohols is based on barrier discharge processes, in which the plasma is generated by high-voltage AC discharges (generally between 5 and 30 kV) and frequencies in the kHz range (Eliasson B., IEEE Transactions on Plasma Science, 19, 1063-1077 (1991); Hammer T., Contributions to Plasma Physics, 39, 441-462
(1999) ), aunque hay resultados descritos sobre la utilización de 50 Hz de frecuencia (Aghamir Farzin M. ,(1999)), although there are results described on the use of 50 Hz frequency (Aghamir Farzin M.,
Matin Nasser S., Jalili Amir-hossein and Esfarayeni Mohammad-Ali, Methanol Production in AC DielectricMatin Nasser S., Jalili Amir-hossein and Esfarayeni Mohammad-Ali, Methanol Production in AC Dielectric
Barrier Discharge, J. Plasma Fusión Res. Series, VoI. 6Barrier Discharge, J. Plasma Fusion Res. Series, VoI. 6
(2004) 696-698). De nuevo, en este caso, suele ser normal la obtención de mezclas de reacción donde, además de los gases deseados, se encuentren cantidades significativas de hidrocarburos y/o alcoholes superiores. (Shigeru Futamura, Hajime Kabashima, and Hisahiro Einaga, Steam Reforming of Aliphatic Hydrocarbons With Nonthermal Plasma, IEEE Transactions on industry applications, vol . 40, no. 6, November/December 2004) . En la mayoría de todos estos procesos es normal añadir al reactor una mezcla en las proporciones adecuadas del combustible y agua o CO2 (Shigeru Futamura and Gurusamy Annadurai, Plasma Reforming of Aliphatic Hydrocarbons With CO2' IEEE Transactions on industry applications, vol. 41, no. 6, November/December 2005) . Sin embargo, existe una referencia reciente de un proceso donde mediante la utilización de plasmas de descarga barrera se reivindica la posibilidad de proceder a la disociación directa del metano en carbono (sólido) e hidrógeno (David E. Fletcher, United States patent application publication No. US 2004/0148860 Al, Aug. 5, 2004). El reactor utilizado en este caso integra un mecanismo complejo donde un electrodo cónico y estriado a modo de tornillo gira a gran velocidad enfrentado a un cono hueco de material dieléctrico donde se aplica el otro electrodo. Un elemento esencial en el desarrollo de los plasmas de descarga barrera lo constituye el tipo de descarga utilizada y el modo en que ésta se aplica. Generalmente, uno de los electrodos del sistema se activa mediante la descarga de alto voltaje AC, mientras que el otro suele colocarse a tierra (Ulrich Kogelschatz, Dielectric- Barrier Discharges: Their History, Discharge Physics, and Industrial Applications, Plasma Chemistry and Plasma Processing, Volume 23, Number 1, March 2003 pages 1 - 46) . Una de las características diferenciales del procedimiento de la invención tiene que ver con el modo de aplicar el voltaje externo. Otro elemento característico presente en alguna de las patentes existentes sobre reactores DBD, es la utilización de un metal poroso como electrodo activo, a través de cuyos poros circula el gas o mezcla de gases utilizada. Aparentemente una naturaleza singular de las microdescargas producidas en dichos poros (condiciones similares a las denominadas "hollow cathode") puede tener una influencia importante en el control de las características del proceso (Yun Yang, Alternating- Current Glow and Pseudoglow Discharges in Atmospheric Pressure, IEEE Transactions on plasma science, vol . 31, no. 1, February 2003) .(2004) 696-698). Again, in this case, it is usually normal to obtain reaction mixtures where, in addition to the desired gases, significant amounts of hydrocarbons and / or higher alcohols are found. (Shigeru Futamura, Hajime Kabashima, and Hisahiro Einaga, Steam Reforming of Aliphatic Hydrocarbons With Nonthermal Plasma, IEEE Transactions on industry applications, vol. 40, no. 6, November / December 2004). In most of all these processes it is normal to add a mixture in the appropriate proportions of the fuel and water or CO 2 to the reactor (Shigeru Futamura and Gurusamy Annadurai, Plasma Reforming of Aliphatic Hydrocarbons With CO 2 'IEEE Transactions on industry applications, vol. 41 , no.6, November / December 2005). However, there is a recent reference to a process where, through the use of barrier discharge plasmas, the possibility of direct dissociation of methane into carbon (solid) and hydrogen is claimed (David E. Fletcher, United States patent application publication No US 2004/0148860 Al, Aug. 5, 2004). The reactor used in this case integrates a complex mechanism where a screw-shaped conical electrode rotates at high speed in front of a hollow cone of dielectric material where the other electrode is applied. An essential element in the development of barrier discharge plasmas is the type of discharge used and how it is applied. Generally, one of the electrodes of the system is activated by high-voltage AC discharge, while the other is usually grounded (Ulrich Kogelschatz, Dielectric-Barrier Discharges: Their History, Discharge Physics, and Industrial Applications, Plasma Chemistry and Plasma Processing , Volume 23, Number 1, March 2003 pages 1-46). One of the differential characteristics of the process of the invention has to do with how to apply the external voltage. Another characteristic element present in one of the existing patents on DBD reactors, is the use of a porous metal as an active electrode, through whose pores the gas or mixture of gases used circulates. Apparently a unique nature of the micro discharge produced in said pores (conditions similar to the so-called "hollow cathode") can have an important influence on the control of the process characteristics (Yun Yang, Alternating- Current Glow and Pseudoglow Discharges in Atmospheric Pressure, IEEE Transactions on plasma science, vol. 31, no. 1, February 2003).
BREVE DESCRIPCIÓN DE LAS FIGURASBRIEF DESCRIPTION OF THE FIGURES
Figura 1.- Modo de conexión y descripción esquemática de la estructura eléctrica del reactorFigure 1.- Connection mode and schematic description of the electrical structure of the reactor
1. Fuente de potencial1. Potential source
2. Electrodo (cilindro interno) 3. Electrodo (capa metálica externa)2. Electrode (internal cylinder) 3. Electrode (external metallic layer)
4. Tubo de material dieléctrico Figura 2.- Esquema general del sistema de reacción 1.- Líneas de conducción de gases/vapores de entrada y salida calentables4. Tube of dielectric material Figure 2.- General scheme of the reaction system 1.- Lines of conduction of gases / vapors of entrance and exit heated
2.- Reactor de descarga barrera2.- Barrier discharge reactor
3.- Conexión al sistema de control y análisis de gases. Figura 3.- Esguema general del reactor3.- Connection to the gas analysis and control system. Figure 3.- General reactor scheme
1.- Cilindro de acero macizo o tubular con rugosidad superficial controlada en la zona de la descarga.1.- Solid or tubular steel cylinder with controlled surface roughness in the discharge zone.
2.- Conexiones eléctricas de alto voltaje de los electrodos metálicos activos . 3.- zona de aislamiento dieléctrico2.- High voltage electrical connections of the active metal electrodes. 3.- dielectric isolation zone
4.- Flechas indicando el flujo de gases4.- Arrows indicating the flow of gases
5. - Tubo de material dieléctrico5. - Tube of dielectric material
6.- Capa metálica que actúa como electrodo6.- Metal layer that acts as an electrode
7.- Horno de calefacción Figura 4.- Ejemplo sobre la eficacia del proceso expresada en términos de porcentaje de descomposición de7.- Heating furnace Figure 4.- Example of the efficiency of the process expressed in terms of the percentage of decomposition of
CH4 en mezclas equimoleculares de este gas con CO2 en función del flujo de los reactivos.CH 4 in equimolecular mixtures of this gas with CO 2 depending on the flow of the reagents.
DESCRIPCIÓN DETALIADA DE LA INVENCIÓNDETAILED DESCRIPTION OF THE INVENTION
La presente invención se refiere a un procedimiento para el reformado de combustibles gaseosos o líquidos vaporables, en un reactor de plasma de descarga barrera que comprende las siguientes etapas: a) la introducción de una mezcla en forma de vapor o gas entre el combustible y CO2 y/o H2O, en proporciones comprendidas entre 1:1 y 1:10 en el reactor de descarga barrera para su tratamiento en forma continua y a presión atmosférica. b) el ajuste en el reactor de las condiciones de la descarga, particularmente el valor de alto voltaje y de frecuencia, así como las condiciones de temperatura, c) la activación del reactor una vez ajustadas las condiciones en la etapa anterior.The present invention relates to a process for reforming gaseous fuels or vaporable liquids, in a plasma barrier discharge reactor comprising the following steps: a) the introduction of a vapor or gas mixture between the fuel and CO2 and / or H2O, in proportions between 1: 1 and 1:10 in the barrier discharge reactor for continuous treatment and at atmospheric pressure. b) adjustment in the reactor of the discharge conditions, particularly the high voltage value and frequency, as well as temperature conditions, c) the activation of the reactor once the conditions in the previous stage have been adjusted.
La descarga se realiza suministrando un potencial AC de alto voltaje comprendido entre preferentemente 0.5 y 80 kV, más preferentemente entre 15 y 30 kV y de frecuencia comprendida entre preferentemente 50 Hz y 70 kHz, más preferentemente entre 3 y 15 kHz, aplicado entre los dos electrodos del reactor de descarga barrera cambiando la polaridad alternativamente, sin que ninguno de esos electrodos esté en ningún momento conectado a tierra. Cuando se introduce una mezcla combustible/C02 se emplea una proporción comprendida entre preferentemente I y 10. Cuando se introduce una mezcla combustible/H2θ se emplea igualmente una proporción comprendida preferentemente entre 1 y 10. Cuando se introduce una mezcla a tres, combustible/Cθ2/H2θ, la proporción está comprendida preferentemente entre 1:0.5:0.5 y 1:5:5.The discharge is performed by supplying a high voltage AC potential between preferably 0.5 and 80 kV, more preferably between 15 and 30 kV and a frequency between preferably 50 Hz and 70 kHz, more preferably between 3 and 15 kHz, applied between the two Barrier discharge reactor electrodes changing polarity alternately, without any of those electrodes being grounded at any time. When a fuel / C0 2 mixture is introduced, a proportion between preferably I and 10 is used. When a fuel / H 2 mixture is introduced, a proportion preferably between 1 and 10 is also used. When a mixture is introduced to three, fuel / Cθ 2 / H 2 θ, the ratio is preferably between 1: 0.5: 0.5 and 1: 5: 5.
En el caso de que se reformen combustibles líquidos y/o H2O líquida, se incluye una etapa previa de vaporización por calentamiento. Adicionalmente se puede agregar oxígeno a la mezcla del combustible con CO2 y/o H2O, en una proporción comprendida entre 0.1 y 0.3% respecto al combustible. El flujo de la mezcla de reacción está comprendido entre 1 y 100 centímetros cúbicos standard por minuto (sccm) dependiendo del tamaño del reactor, y los combustibles utilizados son preferentemente hidrocarburos, alcoholes, gas natural o mezclas de ellos, más preferentemente combustibles comerciales en forma de fluidos volatilizables tales como gasolinas ó gas-oil. Los productos obtenidos mediante el procedimiento de reformado objeto de la presente invención tienen un contenido en hidrocarburos superiores inferior al 1% y un contenido en CO + H2 correspondientes a conversiones de metano de hasta el 95%.In the event that liquid fuels and / or liquid H 2 O are reformed, a previous stage of vaporization by heating is included. Additionally, oxygen can be added to the fuel mixture with CO 2 and / or H2O, in a proportion between 0.1 and 0.3% with respect to the fuel. The flow of the reaction mixture is between 1 and 100 standard cubic centimeters per minute (sccm) depending on the size of the reactor, and the fuels used are preferably hydrocarbons, alcohols, natural gas or mixtures thereof, more preferably commercial fuels in the form of volatile fluids such as gasoline or gas-oil. The products obtained by the reforming process object of the present invention have a hydrocarbon content of less than 1% and a CO + H2 content corresponding to methane conversions of up to 95%.
Constituye igualmente un objeto de la presente invención, un reactor de plasma de descarga barrera para el reformado de combustibles, que comprende los siguientes elementos : a) una fuente de alimentación que suministra una corriente alterna de alto voltaje, comprendido entre 0,5 y 80 kV, preferentemente entre 15 y 30 kV, y de frecuencia comprendida entre 50 Hz y 70 kHz, preferentemente entre 3 y 15 kHz; b) un electrodo cilindrico de acero que incorpora en su exterior una lámina de metal y conectado a una fuente de alimentación de alto voltaje; y c) un dispositivo dieléctrico de geometría cilindrica colocado en forma concéntrica exteriormente al electrodo cilindrico .It is also an object of the present invention, a barrier discharge plasma reactor for reforming fuels, comprising the following elements: a) a power supply that supplies a high voltage alternating current, between 0.5 and 80 kV, preferably between 15 and 30 kV, and with a frequency between 50 Hz and 70 kHz, preferably between 3 and 15 kHz; b) a cylindrical steel electrode that incorporates a metal sheet outside and connected to a high voltage power supply; and c) a cylindrical geometry dielectric device placed concentrically outside the cylindrical electrode.
La superficie del electrodo de acero presenta preferentemente, una rugosidad superficial caracterizada por motivos rugosos de tamaño comprendido entre 1 y 10 μm y la distancia entre el electrodo cilindrico de acero y el dispositivo dieléctrico, correspondiente a la zona de descarga está comprendida entre 1 y 10 mm, preferentemente entre 1 y 3 mm. En una realización preferente, el dispositivo dieléctrico se construye en cuarzo, alúmina o cerámica y presenta un espesor comprendido entre 1 y 10 mm. Opcionalmente, el reactor presenta unas dimensiones comprendidas entre 8 y 40 cía de largo y entre 1.5 y 20 era de diámetro.The surface of the steel electrode preferably has a surface roughness characterized by rough motifs of size between 1 and 10 μm and the distance between the cylindrical steel electrode and the dielectric device, corresponding to the discharge zone is between 1 and 10 mm, preferably between 1 and 3 mm. In a preferred embodiment, the dielectric device is constructed in quartz, alumina or ceramic and has a thickness between 1 and 10 mm. Optionally, the reactor has dimensions between 8 and 40 cm long and between 1.5 and 20 era in diameter.
En una realización preferida, el reactor incluye elementos de control de la temperatura de la zona de reacción, que permiten su regulación entre la temperatura ambiente y 5000C.In a preferred embodiment, the reactor includes control elements the temperature of the reaction zone, which allow regulation between room temperature and 500 0 C.
En el reactor objeto de la presente invención, la fuente de alimentación no trabaja entre un electrodo activo y otro a tierra, sino que opera aplicando alternativamente el alto voltaje entre los dos electrodos que, de esta manera, actúan ambos como electrodos activos.In the reactor object of the present invention, the power supply does not work between one active electrode and another to ground, but instead operates by applying the high voltage alternately between the two electrodes which, in this way, both act as active electrodes.
Para la realización del proceso de reformado de combustibles mediante plasmas de barrera dieléctrica, se ha construido un reactor basado en este principio que se alimenta eléctricamente con una fuente AC de alto voltaje tal y como se describe esquemáticamente en la Figura 1. En esta figura se pone de manifiesto que, como elemento novedoso respecto a otros reactores DBD previamente utilizados, en el proceso aqui desarrollado ninguno de los dos electrodos se conecta a tierra, sino que se activan sucesivamente y de forma opuesta con voltajes positivos y negativos suministrados por la fuente. La fuente de potencial construida y que constituye una parte indisociable del reactor para la realización del proceso de reformado, es una fuente de corriente alterna con frecuencia variable preferentemente entre 50 Hz y 70 kHz, más preferentemente entre 3 y 15 kHz, y que suministra voltajes pico a pico comprendidos preferentemente entre 0.5 y 80 kV, más preferentemente entre 15 y 30 kV. El reactor se integra en un sistema de reacción general donde es posible dosificar cantidades controladas de los reactivos (Figura 2) . Tanto los tubos de alimentación de reactivos como los de salida de productos se pueden calentar a temperaturas controladas por encima de 100°C. Es necesario proceder a este calentamiento en el caso de utilizar agua y/o combustibles líquidos que sea necesario vaporizar antes de alimentar la mezcla en el reactor. El control del flujo de gases puede hacerse mediante controladores de flujo (gases) o sistemas de control de flujo de líquidos en el sistema de tubos de alimentación del reactor.For the realization of the fuel reforming process by means of dielectric barrier plasmas, a reactor based on this principle has been constructed that is electrically fed with a high-voltage AC source as described schematically in Figure 1. In this figure, shows that, as a novel element with respect to other previously used DBD reactors, in the process developed here neither of the two electrodes are connected to ground, but are activated successively and in the opposite way with positive and negative voltages supplied by the source. The source of potential built and constituting an inseparable part of the reactor for the realization of the reforming process, is an alternating current source with a variable frequency preferably between 50 Hz and 70 kHz, more preferably between 3 and 15 kHz, and which supplies voltages peak to peak preferably between 0.5 and 80 kV, more preferably between 15 and 30 kV. The reactor is integrated into a general reaction system where it is possible to dose controlled quantities of the reagents (Figure 2). Both reagent feed and product outlet tubes can be heated to controlled temperatures above 100 ° C. It is necessary to proceed to this heating in the case of using water and / or liquid fuels that it is necessary to vaporize before feeding the mixture into the reactor. Gas flow control can be done by flow controllers (gases) or liquid flow control systems in the reactor feed tube system.
El control de los gases de salida (composición, etc.) puede hacerse mediante un sistema de análisis directamente conectado al tubo de gases de salida.The control of the exhaust gases (composition, etc.) can be done by means of an analysis system directly connected to the outlet gas tube.
Como puede observarse en el dibujo esquemático de la Figura 3, el reactor está formado por un cilindro de acero, cuya superficie externa en la zona de descarga ha sido sometido a un proceso de abrasión controlada para producir una superficie rugosa de características definidas. El cilindro se conecta a la alimentación de alto voltaje de la fuente y a un tubo de alimentación de acero. Para evitar que a través de este tubo se active eléctricamente todo el sistema de tuberías de alimentación, aquél se aisla eléctricamente de las tuberías, acoplando en una zona intermedia un tubo de vidrio u otro material dieléctrico. El cilindro de acero se coloca concéntrico a un tubo de un material dieléctrico (cuarzo, alúmina o cualquier otra cerámica) de espesor comprendido entre 1 y 10 πun, de manera que la mezcla de reacción circule entre el cilindro de acero y el tubo cerámico. La distancia entre ambos es otro de los parámetros críticos del proceso y puede variar entre 1 y 10 mm. Por la parte exterior del cilindro, se coloca una lámina de metal que actúa como el otro electrodo activo del proceso. El plasma en la zona de circulación de la mezcla de gases, se forma coincidiendo con la superficie del cilindro metálico que tiene arrollada la capa metálica, pudiendo en consecuencia ser variada a voluntad. Todo el conjunto está rodeado por un pequeño horno para mantener el conjunto por encima de 100 °C en caso de que se use H2O y/o combustibles líquidos en la mezcla de reacción.As can be seen in the schematic drawing of Figure 3, the reactor is formed by a steel cylinder, whose external surface in the discharge zone has been subjected to a controlled abrasion process to produce a rough surface of defined characteristics. The cylinder is connected to the source's high voltage supply and a steel feeding tube. To prevent the entire supply pipe system from being electrically activated through this tube, it is electrically isolated from the pipes, coupling a glass tube or other dielectric material in an intermediate zone. The steel cylinder is placed concentric to a tube of a dielectric material (quartz, alumina or any other ceramic) of thickness between 1 and 10 πun, so that the reaction mixture circulates between the steel cylinder and the ceramic tube. The distance between the two is another one of the Critical process parameters and may vary between 1 and 10 mm. On the outside of the cylinder, a sheet of metal is placed that acts as the other active electrode in the process. The plasma in the circulation zone of the gas mixture is formed coinciding with the surface of the metal cylinder that has the metal layer wound, and can therefore be varied at will. The entire assembly is surrounded by a small oven to keep the assembly above 100 ° C in case H 2 O and / or liquid fuels are used in the reaction mixture.
Todo el sistema de reacción anterior se puede integrar en una carcasa de protección y aislamiento si así se considera necesario. El reactor presenta unas dimensiones características comprendidas entre 8 y 40 cm de largo y entre 1,5 y 20 cm de diámetro .The entire previous reaction system can be integrated into a protective and insulating housing if deemed necessary. The reactor has characteristic dimensions between 8 and 40 cm long and between 1.5 and 20 cm in diameter.
Las reacciones que se pueden activar mediante el reactor desarrollado, se pueden esquematizar según:The reactions that can be activated by the developed reactor can be schematized according to:
CnH1n + CO2 -> CO + H2 [1]C n H 1n + CO 2 -> CO + H 2 [1]
CnHm + H2O ^ CO + H2 [2]C n H m + H 2 O ^ CO + H 2 [2]
donde CnHm puede indicar un hidrocarburo, mezclas de hidrocarburos, un alcohol o mezclas de aleñóles y/o hidrocarburos .where C n H m may indicate a hydrocarbon, mixtures of hydrocarbons, an alcohol or mixtures of alloys and / or hydrocarbons.
Con el sistema de reacción anteriormente descrito se puede realizar el reformado del (de los) combustible (s) seleccionado (s) cambiando distintas variables del proceso, como son el voltaje y la frecuencia de la descarga, la temperatura del reactor, el flujo total de la mezcla de reacción o la proporción entre el hidrocarburo/alcohol y el otro reactivo seleccionado (H2O o CO2) . Con el dispositivo se puede también inducir la disociación directa del hidrocarburo en C (sólido) e H2. Aunque experimentos de este tipo han podido realizarse durante periodos de tiempo de hasta 45 min, su ejecución no es recomendable ya que el carbono producido que permanece en el interior de la zona de descarga puede servir de punto de inducción de descargas indeseadas.With the reaction system described above, the refurbishment of the selected fuel (s) can be carried out by changing different process variables, such as the voltage and frequency of the discharge, the reactor temperature, the total flow from the reaction mixture or the ratio between the hydrocarbon / alcohol and the other reagent selected (H 2 O or CO 2 ). With the device, the direct dissociation of the hydrocarbon into C (solid) and H 2 can also be induced. Although experiments of this type have been able to be carried out for periods of up to 45 min, its execution is not recommended since the carbon produced that remains inside the discharge zone can serve as an induction point for unwanted discharges.
EJEMPLO DE REALIZACIÓN DE IA INVENCIÓNEXAMPLE OF REALIZATION OF THE INVENTION
Un ejemplo de aplicación del procedimiento lo constituye el reformado de metano (CH4) , usando CO2 como el otro gas del proceso en un reactor con unas dimensiones de 10 cm de largo y 3 cm de diámetro. Para esta mezcla de reacción se ha medido la eficacia del proceso y se ha verificado que, dependiendo de las condiciones de trabajo y de las características de la fuente, se pueden conseguir conversiones prácticamente totales del metano con la formación de una mezcla de CO e H2 que se puede escribir, de acuerdo a la reacción [1] ajustada estequiométricamente, según:An example of application of the procedure is methane reforming (CH 4 ), using CO 2 as the other process gas in a reactor with dimensions 10 cm long and 3 cm in diameter. For this reaction mixture the efficiency of the process has been measured and it has been verified that, depending on the working conditions and the characteristics of the source, practically total conversions of methane can be achieved with the formation of a mixture of CO and H 2 that can be written, according to the reaction [1] stoichiometrically adjusted, according to:
CH4 + CO2 -» 2CO + 2 H2 [3]CH 4 + CO 2 - »2CO + 2 H 2 [3]
Conviene destacar que como producto de la reacción sólo se detectaron trazas de hidrocarburos superiores, siempre por debajo de un limite superior del 1%. Esta ausencia de hidrocarburos superiores se puede considerar como una de las características más singulares del proceso desarrollado. En el rendimiento de la reacción [3] influyen muchos parámetros como se dijo previamente. Un ejemplo de cómo varía la eficacia de la reacción en función de parámetros del proceso, se presenta en la Figura 4 que representa el tanto por ciento de conversión de metano para una frecuencia y voltaje dados, en función del flujo total de gases a través del reactor. Como es previsible, el porcentaje de conversión varía de modo inversamente proporcional al flujo de gases, tal y como cabe esperar de procesos donde el tiempo de residencia en el reactor debe ser un factor controlador de máxima importancia.It should be noted that as a result of the reaction, only traces of higher hydrocarbons were detected, always below an upper limit of 1%. This absence of higher hydrocarbons can be considered as one of the most unique characteristics of the process developed. Many parameters influence the performance of the reaction [3] as previously stated. A An example of how the efficiency of the reaction varies according to process parameters is presented in Figure 4, which represents the percentage of methane conversion for a given frequency and voltage, as a function of the total gas flow through the reactor . As expected, the conversion rate varies inversely proportional to the gas flow, as can be expected from processes where the residence time in the reactor must be a controlling factor of the utmost importance.
Según los datos de la gráfica representada en la Figura 4, la temperatura es también un parámetro de gran importancia que, para valores por encima de 120° C influye disminuyendo el rendimiento de la reacción.According to the data in the graph represented in Figure 4, the temperature is also a parameter of great importance that, for values above 120 ° C, influences reducing the reaction yield.
El presente ejemplo se introduce a modo ilustrativo del funcionamiento de la presente invención, sin ser en modo alguno, limitativo de su alcance. The present example is introduced by way of illustration of the operation of the present invention, without being in any way limiting its scope.

Claims

REIVINDICACIONES
1.- Procedimiento para el reformado de combustibles gaseosos o líquidos vaporables en un reactor de plasma de descarga barrera caracterizado porque comprende las siguientes etapas: a) introducción de una mezcla en forma de vapor o gas de combustible y, CO2 y/o H2O, en proporciones comprendidas entre 1:1 y 1:10 en un reactor de descarga barrera para su tratamiento en forma continua y a presión atmosférica; b) ajuste en el reactor de las siguientes condiciones de la descarga: el valor de alto voltaje, la frecuencia, y la temperatura; c) activación del reactor una vez ajustadas las condiciones en la etapa anterior; de forma que la descarga se realiza suministrando un potencial AC de alto voltaje aplicado entre los dos electrodos del reactor de descarga barrera cambiando la polaridad alternativamente sin que ninguno de esos electrodos esté en ningún momento conectado a tierra.1.- Procedure for reforming gaseous fuels or vaporable liquids in a barrier plasma discharge reactor characterized in that it comprises the following steps: a) introduction of a mixture in the form of steam or fuel gas and, CO 2 and / or H 2 O, in proportions between 1: 1 and 1:10 in a barrier discharge reactor for continuous treatment at atmospheric pressure; b) adjustment in the reactor of the following discharge conditions: high voltage value, frequency, and temperature; c) activation of the reactor once the conditions in the previous stage have been adjusted; so that the discharge is performed by supplying a high voltage AC potential applied between the two electrodes of the barrier discharge reactor by changing the polarity alternately without any of those electrodes being grounded at any time.
2.- Procedimiento para el reformado de combustibles según la reivindicación 1, caracterizado porque dicho potencial AC de alto voltaje está comprendido entre 0,5 y 80 kV, y su frecuencia está comprendida entre 50 Hz y 70 kHz .2. Method for reforming fuels according to claim 1, characterized in that said high voltage AC potential is between 0.5 and 80 kV, and its frequency is between 50 Hz and 70 kHz.
3.- Procedimiento para el reformado de combustibles según la reivindicación 2, caracterizado porque dicho potencial AC de alto voltaje está comprendido entre 15 y 30 kV y dicha frecuencia está comprendida entre 3 y 15 kHz. 3. Method for reforming fuels according to claim 2, characterized in that said high voltage AC potential is between 15 and 30 kV and said frequency is between 3 and 15 kHz.
4.- Procedimiento para el reformado de combustibles según una de las reivindicaciones 1 a 3, caracterizado porque cuando se introduce una mezcla combustible/C02 se emplea una proporción comprendida entre I y 10.4. Method for reforming fuels according to one of claims 1 to 3, characterized in that when a fuel / C0 2 mixture is introduced, a proportion between I and 10 is used.
5.- Procedimiento para el reformado de combustibles según una de las reivindicaciones 1 a 3, caracterizado porque cuando se introduce una mezcla combustible/E^O se emplea una proporción comprendida entre 1 y 10.5. Method for reforming fuels according to one of claims 1 to 3, characterized in that when a fuel / E ^ O mixture is introduced, a ratio between 1 and 10 is used.
6.- Procedimiento para el reformado de combustibles según una de las reivindicaciones 1 a 3, caracterizado porque cuando se introduce una mezcla combustible/ CO2/H2O, se emplea una proporción comprendida entre 1:0,5:0,5 y 1:5:5.6. Method for reforming fuels according to one of claims 1 to 3, characterized in that when a fuel / CO 2 / H 2 O mixture is introduced, a ratio between 1: 0.5: 0.5 and 1: 5: 5.
7.- Procedimiento para el reformado de combustibles según una de las reivindicaciones 1 a 6, caracterizado porque cuando se reforman combustibles líquidos y/o H2O liquida se incluye una etapa previa de vaporización por calentamiento .7. Method for reforming fuel according to one of claims 1 to 6, characterized in that when liquid fuels are reformed and / or H 2 O liquid includes a prior step of vaporization by heating.
8.- Procedimiento para el reformado de combustibles según una de las reivindicaciones 1 a 7, caracterizado porque adicionalmente se agrega oxigeno a la mezcla del combustible con CO2 y/o H2O, en una proporción comprendida entre 0,1% y 0,3% respecto al combustible.8. Method for reforming fuels according to one of claims 1 to 7, characterized in that additionally oxygen is added to the fuel mixture with CO 2 and / or H 2 O, in a proportion between 0.1% and 0 , 3% compared to fuel.
9.- Procedimiento para el reformado de combustibles según una de las reivindicaciones 1 a 8, caracterizado porque el flujo de la mezcla de reacción está comprendido entre 1 sccm y 100 sccm.9. Method for reforming fuels according to one of claims 1 to 8, characterized in that The flow of the reaction mixture is between 1 sccm and 100 sccm.
10.- Procedimiento para el reformado de combustibles según una de las reivindicaciones 1 a 9, caracterizado porque los combustibles utilizados están seleccionados entre hidrocarburos, alcoholes, gas natural y mezclas de ellos .10. Process for reforming fuels according to one of claims 1 to 9, characterized in that the fuels used are selected from hydrocarbons, alcohols, natural gas and mixtures thereof.
11.- Procedimiento para el reformado de combustibles según la reivindicación 10, caracterizado porque dichos hidrocarburos son combustibles comerciales en forma de fluidos volatilizables .11. Method for reforming fuels according to claim 10, characterized in that said hydrocarbons are commercial fuels in the form of volatile fluids.
12.- Procedimiento para el reformado de combustibles según la reivindicación 11, caracterizado porque dichos combustibles comerciales están seleccionados entre gasolinas ó gas-oil.12. Method for reforming fuels according to claim 11, characterized in that said commercial fuels are selected from gasoline or gas-oil.
13.- Procedimiento para el reformado de combustibles según una de las reivindicaciones 1 a 12, caracterizado porque los productos obtenidos en el reformado tienen un contenido en hidrocarburos superiores, inferior al 1% y un contenido en CO + H2 correspondientes a conversiones de combustible de hasta el 95%.13. Process for reforming fuels according to one of claims 1 to 12, characterized in that the products obtained in the reforming have a higher hydrocarbon content, less than 1% and a CO + H 2 content corresponding to fuel conversions up to 95%.
14.- Reactor de plasma de descarga barrera para el reformado de combustibles que comprende los siguientes elementos: a) una fuente de alimentación que suministra una corriente alterna de alto voltaje, comprendido entre 0,5 y 80 kV; b) un electrodo cilindrico de acero que incorpora en su exterior una lámina de metal, conectado a una fuente de alimentación de alto voltaje, y que presenta una rugosidad superficial con motivos rugosos; c) un dispositivo dieléctrico de geometría cilindrica colocado de forma concéntrica en el exterior del electrodo, de modo que la distancia entre el electrodo cilindrico de acero y el dispositivo dieléctrico, correspondiente a la zona de descarga es de entre 1 y 10 iran.14.- Barrier discharge plasma reactor for fuel reforming comprising the following elements: a) a power supply that supplies a high voltage alternating current, between 0.5 and 80 kV; b) a cylindrical steel electrode that incorporates a sheet of metal on its exterior, connected to a high-voltage power supply, and which has a surface roughness with rough motifs; c) a cylindrical geometry dielectric device placed concentrically outside the electrode, so that the distance between the steel cylindrical electrode and the dielectric device, corresponding to the discharge zone is between 1 and 10 iran.
15.- Reactor de plasma de descarga barrera para el reformado de combustibles según la reivindicación 14, caracterizado porque dicha corriente alterna de alto voltaje posee una frecuencia comprendida entre 50 Hz y 70 kHz.15.- Barrier discharge plasma reactor for reforming fuels according to claim 14, characterized in that said high voltage alternating current has a frequency between 50 Hz and 70 kHz.
16.- Reactor de plasma de descarga barrera para el reformado de combustibles según una de las reivindicaciones 14 o 15, caracterizado porque dichos motivos rugosos del electrodo cilindrico poseen un tamaño comprendido entre 1 y 10 Dm.16.- Barrier discharge plasma reactor for reforming fuels according to one of claims 14 or 15, characterized in that said rough motifs of the cylindrical electrode have a size between 1 and 10 Dm.
17.- Reactor de plasma de descarga barrera para el reformado de combustibles según una de las reivindicaciones 14 a 16, caracterizado porque la fuente de alimentación suministra una corriente alterna con un voltaje de entre 15 y 30 kV, y una frecuencia de entre 3 y 15 kHz.17.- Barrier discharge plasma reactor for reforming fuels according to one of claims 14 to 16, characterized in that the power supply supplies an alternating current with a voltage between 15 and 30 kV, and a frequency between 3 and 15 kHz
18.- Reactor de plasma de descarga barrera para el reformado de combustibles según una de las reivindicaciones 14 a 17, caracterizado porque dicha distancia entre el electrodo y el dispositivo dieléctrico es de entre 1 y 3 mm.18.- Barrier discharge plasma reactor for reforming fuels according to one of the claims 14 to 17, characterized in that said distance between the electrode and the dielectric device is between 1 and 3 mm.
19.- Reactor de plasma de descarga barrera para el reformado de combustibles según una de las reivindicaciones 14 a 18, caracterizado porque el dispositivo dieléctrico se construye en cuarzo, alúmina o cerámica y presenta un espesor comprendido entre 1 y 10 mm.19.- Barrier discharge plasma reactor for reforming fuels according to one of claims 14 to 18, characterized in that the dielectric device is constructed of quartz, alumina or ceramic and has a thickness between 1 and 10 mm.
20.- Reactor de plasma de descarga barrera según una de las reivindicaciones 14 a 19, caracterizado porque dicho reactor presenta unas dimensiones comprendidas entre 8 y 40 cm de largo y entre 1,5 y 20 cm de diámetro.20.- Plasma barrier discharge reactor according to one of claims 14 to 19, characterized in that said reactor has dimensions between 8 and 40 cm long and between 1.5 and 20 cm in diameter.
21.- Reactor de plasma de descarga barrera según una de las reivindicaciones 14 a 20, caracterizado porque posee elementos de control de la temperatura de la zona de reacción que permite regularla entre la temperatura ambiente y 500°C. 21.- Plasma barrier discharge reactor according to one of claims 14 to 20, characterized in that it has temperature control elements of the reaction zone that allows it to be adjusted between room temperature and 500 ° C.
PCT/ES2007/000214 2006-06-01 2007-04-12 Procedure and reactor for the reformation of fuels WO2007141350A1 (en)

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