Patent Application
20080171243
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. § 119 from an application for REACTION VESSEL AND REACTION DEVICE earlier filed in the Korean Intellectual Property Office on the 12 Jan. 2007 and there duly assigned Serial No. 10-2007-0004001.
1. Field of the Invention
The present invention relates to a reaction vessel for a fuel cell, and more particular to a reaction vessel capable of obtaining reaction temperature promptly at the time of initial operation and a reaction device to form reforming device for the fuel cell using the same.
2. Description of the Related Art
A fuel cell is a power generation system used to generate electric energy by electro-chemically reacting hydrogen and oxygen. According to the types of electrolyte used, fuel cells can be categorized into a phosphoric acid fuel cell, a molten carbonate fuel cell, a solid oxide fuel cell, a polymer electrolyte membrane fuel cell, and an alkaline fuel cell, etc. These respective fuel cell types are basically operated on the same principle, but are different in the type of used fuels, catalyst, and electrolytes, etc., as well as operating temperatures. Among the various types of the fuel cells, the polymer electrolyte membrane fuel cell (PEMFC) has several advantages over other fuel cells, including a remarkably high output, low operating temperature, and rapid starting and response. The PEMFC is widely applicable to a mobile power source, such as portable electronic equipment or a transportable power source, such as a power source for automobiles, as well as a distributed power source, such as a stationary power plant used in a house and a public building, etc.
In an electrochemical oxidation reaction generated in an anode electrode of a fuel cell, hydrogen has the best reactivity. And hydrogen is most suitable for fuel of the fuel cell since it generates water and does not discharge a pollutant after reaction with oxygen. However, hydrogen hardly exists in a natural condition, and therefore it may be obtained by reforming other materials. For example, hydrogen may be obtained by reforming a hydro-carbonaceous fuel such as gasoline, diesel, methanol, ethanol, natural gas etc. Further, hydrogen may be easily obtained from a fuel product such as a butane can etc., which are commercially available. Accordingly, if the butane can is used as a fuel supply source of the fuel cell, there is the advantage of supplying fuel by using inner pressure of the butane can.
In order to generate hydrogen from the hydro-carbonaceous fuel, a reformer is provided. The reformer may include a reforming reactor, a water gas shift unit, and a preferential oxidation unit to improve reforming efficiency. The reforming reactor may include a steam reforming reactor and an autothermal reactor.
The each reactor requires a different reaction temperature range depending on a catalyst installed therein. For example, a reaction temperature range of a steam reforming (SR) reaction is different depending on the kind of reforming raw material. If the catalyst is for a hydro-carbonaceous fuel such as butane etc., the reaction temperature range is about 600° C. to 900° C., and if the catalyst is for a methanol fuel, the reaction temperature is about 250° C. to 400° C. Reaction temperature range of a water gas shift (WGS) reaction, which is one of processes to remove carbon monoxide, is about 200° C. to 350° C., and reaction temperature range of a preferential CO oxidation (PROX) reaction is about 100° C. to 250° C. As mentioned above, the temperature required for the reforming reactor is the highest, and the temperature required for the preferential oxidation unit is the lowest. The temperature required for the water gas shift unit is in a range between the temperature for the reforming reactor and the temperature for the preferential oxidation unit.
In order to maintain the reaction temperature of each device, an electric heater is used as a heating device. Further each device can be implemented by a device which burns hydrocarbon fuel by firing it, or burns some of the hydrocarbon fuels by using a catalyst.
In order to maintain heat of reaction, an oxidation reaction unit for heating, which oxidizes some of hydrocarbon fuels by using a catalyst, may be provided separately. The oxidation reaction unit for heating has a catalyst to promote the oxidation reaction therein, and the oxidation reaction unit generates carbon dioxide and steam with a large amount of heat as a result of the oxidation reaction of the hydrocarbon fuel.
The steam reforming reactor reconstitutes steam and hydrocarbon fuel (hereinafter, referred to as butane) to hydrogen molecules and carbon dioxide by resolving them at high temperature atmosphere. The following Reaction Formula 1 indicates the above mentioned process of the steam reforming reactor. Because a hydrogen molecule in high energy state is generated from a water molecule in low energy state, it is an endothermic reaction, but it has the advantage of generating a large amount of hydrogen.
C4H10+8H2O4CO2+13H2 Reaction Formula 1
The autothermal reforming reactor reconstitutes butane gas and steam to hydrogen molecules and carbon monoxide by reacting butane with oxygen in the air at about the steam reforming reaction temperature. The autothermal reforming reactor generates hydrogen molecules from water molecules like the steam reforming reactor, but it is an exothermic reaction by oxidation of carbon. The Reaction Formula 2 indicates the process of the autothermal reforming reactor.
C4H10+4O24CO2+5H2 Reaction formula 2
In the steam reforming reaction or the autothermal reforming reaction, theoretically, only carbon dioxide is generated, but practically, a large amount of carbon monoxide is also generated by imperfect combustion. In order to reduce the amount of carbon monoxide, the water gas shift unit performs combustion by reaction between carbon monoxide and steam, and generates hydrogen molecules from water molecules. The Reaction Formula 3 indicates the process of the water gas shift unit.
CO+H2OCO2+H2O Reaction Formula 3
As another device to reduce the amount of carbon monoxide, the preferential CO oxidation unit performs perfect combustion by reaction between carbon monoxide and oxygen in the air. The Reaction Formula 4 indicates the reaction process of the preferential CO oxidation unit.
CO+1/2O2CO2 Reaction Formula 4
Reforming efficiency of the reformer plays an important role in the total efficiency of the fuel cell system. Therefore, it is necessary to rapidly heat each reactor of the reformer, in which chemical reaction is performed, to appropriate temperature required for chemical reaction of the reactor. The reactors include a reforming reactor, a water gas shift unit, and a preferential CO oxidation unit. Also, the each reactor may have a structure to maximize a contact area between gas and a reaction catalyst to promote each chemical reaction at the appropriate high temperature.
Meanwhile, a reactor, which does not have a separate heating means such as an oxidation reactor for heating, may need a means to increase temperature up to reaction temperature at the time of initial operation, in which a reaction can occur by activating an oxidation reaction catalyst installed therein. However, in the case of providing a separate electric heating means, the costs of manufacturing the reactor may increase.
The present invention is proposed to solve the above mentioned problems. One of objectives is to provide a device capable of obtaining reaction temperature that is necessary for the reaction between gas and a catalyst at the time of initial operation.
Another objective of the present invention is to provide a reaction vessel and a reaction device capable of having a device for obtaining the initial reaction temperature at relatively low cost.
In one embodiment of the present invention, a reaction vessel to perform a chemical reaction is provided. The reaction vessel comprises a monolithic chain having a first end and a second end, and having a plurality of passages through which a material passes to perform the chemical reaction. The passages are formed in a direction that is not parallel to a path connecting the first end to the second end. The monolith chain includes an insulating film extending from the first end to the second end, and a conductive film extending from the first end to the second end. Specifically, the reaction vessel includes a monolithic chain that may have a first side, a second side facing the first side, a top side, and a bottom side facing the top side. The monolithic chain includes a first wall formed along the first side, a second wall formed along the second side, and a layer of pleats interposed between the first wall and the second wall. The passages are defined by pleats of the layer of pleats, and the passages are formed to have openings on each of the top side and the bottom side. At least one of the first wall and the second wall is the insulating film.
The reaction vessel may further include a first connection terminal formed on the first end of the monolithic chain to be connected to a power supplier, and a second connection terminal formed on the second end of the monolithic chain to be connected to the power supplier.
A catalyst required for the chemical reaction is formed on each of the pleats of the layer of pleats. The layer of pleats may be made of a metal. The layer of pleats also can be made of a heating metal material.
The chemical reaction may be an oxidation reaction, and the catalyst is a material such as PdAl2O3, NiO, CuO, CeO2 and Al2O3, Pu, Pd and Pt, or combinations thereof.
A ratio of a total area of the openings formed on the top side of the monolithic chain to a total area of the top side of the monolithic chain is about 40% to 95%. The density of openings formed on the top side of the monolithic chain is about 200 cpi to 1500 cpi.
In another embodiment of the present invention, a reaction device to perform an objective reaction of gas is provided. The reaction device includes an objective reaction catalyst chamber in which the objective reaction is performed by an objective reaction catalyst to promote the objective reaction, and a reaction vessel surrounding the objective reaction catalyst chamber. The reaction vessel includes the monolithic chain that is described above.
The objective reaction catalyst chamber includes a metal monolith that includes a plurality of passages through which the gas flows. The objective reaction catalyst is formed on walls of the passages.
In the case that the objective reaction is a steam reforming reaction, the objective reaction catalyst is made of a material such as Ni/Al2O3, Ru/ZrO2, Ru/Al2O3/Ru/CeO2—Al2O3, or combinations thereof. In the case that the objective reaction is a water gas shift reaction, the objective reaction catalyst is made of a material such as Cu, Zn, Fe, Cr, Cr2O3/Fe3O4, Cu/ZnO/Al2O3, or combinations thereof. In the case that the objective reaction may be a preferential CO oxidation reaction, the objective reaction catalyst is made of a material such as Ru, Rh, Rt/Al2O3, TiO2, ZrO2, Au/Fe2O3, or combinations thereof.
In the case that the reaction vessel reforms hydrocarbon fuel to hydrogen gas, the reaction vessel further comprises a fuel preheater to preheat fuel received from the outside by using heat discharged from the oxidation chamber, wherein the fuel preheater has a tube shape surrounding the oxidation chamber.
In another embodiment of the present invention, a method to heat a reforming reactor for use with a fuel cell is provided. The method comprises the steps of heating a catalyst attached on a monolithic chain with an electrical energy by applying power to the monolithic chain in a reaction vessel which has two connection terminals for applying power from a power supplier for a predetermined period when the fuel cell is turn on; heating the reforming reactor with a chemical energy by applying a fuel and an oxidizing agent which is oxidized on the catalyst attached on the monolithic chain.
The catalyst is formed on pleats of a layer of pleats in the reaction vessel.
A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:
Hereinafter, preferable embodiments according to the principles of the present invention will be described with reference to the accompanying drawings. Here, when one element is connected to another element, one element may be not only directly connected to another element but also indirectly connected to another element via another element. Further, irrelevant elements are omitted for clarity. Also, like reference numerals refer to like elements throughout.
A structure of a reaction vessel of the embodiment of the present invention is illustrated in
Connection terminals 142 and 144 for applying power from a power supplier are formed at both ends of the monolithic chain. As shown in
The monolithic chain has a first side, a second side facing the first side, a top side, and a bottom side facing the top side. First wall 130 is formed along the first side of the monolithic chain, and second wall 120 is formed along the second side of the monolithic chain. A layer of pleats, which has a corrugated structure, is interposed between first wall 130 and second wall 120. Pleat tips may contact either of first wall 130 or second wall 120. Therefore, passages are formed along the pleats inside the monolithic chain, and a plurality of openings 113, which are the end portions of the passages, are formed on the top side and bottom side of the monolithic chain.
At least one of first wall 130 and second wall 120 is made of an insulting material, so that electric current, which flows between first connection terminal 144 and second connection terminal 142, is prevented from flowing in the direction of the radius of the cylinder shaped reaction vessel. The pleats of the layer of pleats works as partitions for dividing passages, which are formed between first wall 130 and second wall 120 inside the monolithic chain. The pleats of the layer of pleats are connected to each other forming a corrugated structure. When viewed from the top side of the monolithic chain, the corrugated structure of the layer of pleats may have a shape of a wave or a wrinkle, but the corrugated structure is not limited to a specific shape. The pleats of the layer of pleats can be regularly or irregularly formed.
In the case that the material of the layer of pleats or one of first and second walls 130 and 120 of the monolithic chain is a metal material, the metal material can be iron alloy or aluminum alloy, if economical efficiency is considered. The metal material can be a heating metal material such as Nichrome that has an excellent electric heating performance, if the performance of heating, such as fasting heating, is considered.
As shown in
When viewed from the top surface of reaction vessel 100, the density of openings 113 formed on the top surface of reaction vessel 100 is about 200 cpi to 1500 cpi (cell per square-inch). If the density of openings 113 is smaller than 200 cpi, reactivity deteriorates due to the decrease of the amount of the catalyst for the chemical reaction. If the density of opening 113 is larger than 1500 cpi, a blocking phenomenon of reacting material is generated.
When viewed from the top surface of reaction vessel 100, the total area of openings 113 formed on the top surface of reaction vessel 100 is about 40% to 95% of the total area of the top surface of reaction vessel 100. If the total area of openings 113 is larger than 95%, reaction vessel 100 may not be sturdy enough, and may have problems in stability at high temperature. In this case, it is also difficult to form the reaction vessel with a metal such as iron or aluminum alloy. If the total area of openings 113 is smaller than 40%, it is difficult to for reaction gas to flow through the reaction vessel, and thereby reaction efficiency deteriorates.
The reaction vessel in
In the case that the reaction vessel is applied to the oxidation reactor for heating, the catalyst formed on passages inside the reaction vessel can be made of a material such as PdAl2O3, NiO, CuO, CeO2 and Al2O3 or plutonium (Pu), palladium (Pd), platinum (Pt), methane, or combinations thereof.
In the case that the reaction vessel is applied to the preferential CO oxidation unit, the catalyst formed on passages inside the reaction vessel can be made of a material such as Ru, Rh, Rt/Al2O3, TiO2, ZrO2 Au/Fe2O3, or combinations thereof.
In the case that the reaction vessel is applied to the autothermal reforming reactor, the catalyst formed on passages inside the reaction vessel can be made of a material such as Ru, Rh, Pt—Rh/Al2O3, TiO2, ZrO2, CeO2, Ce—Zr composite, Au/Fe2O3, or combinations thereof.
The steam reforming device is formed as a cylinder shape, and includes a cylinder shaped steam reforming reaction catalyst chamber 310 and oxidation catalyst chamber 320. In steam reforming reaction catalyst chamber 310, a steam reforming reaction is performed with a steam reforming reaction catalyst to promote the steam reforming reaction. Oxidation catalyst chamber 320 can be built with the monolithic chain as described referring to
As shown in
In other words, outer wall 330 of the steam reforming device functions as a pre-heater to preheat water and butane gas by heat generated from oxidation catalyst chamber 320. In order to prevent waste of heat, outer wall 330 can be constructed to have the waste gas oxidized from the oxidation catalyst 320 pass the space enclosed by the outer wall 330. First wall 330a is used for a region to preheat butane gas, and second wall 330b is used for a region to evaporate water as shown in
Steam reforming reaction catalyst chamber 310 can include a metal monolith as illustrated as square grids in
The catalyst formed inside steam reforming reaction catalyst chamber 310 can be made of a material such as Ni/Al2O3, Ru/ZrO2 Ru/Al2O3/Ru/CeO2—Al2O3, or combinations thereof. Steam reforming reaction catalyst chamber 310 can rapidly and uniformly transfer heat supplied from oxidation catalyst chamber 320 into the inside of steam reforming reaction catalyst chamber 310. Accordingly, temperature inside steam reforming reaction catalyst chamber 310, in which the butane gas contacts the catalyst, rapidly and uniformly increases up to the steam reforming reaction temperature.
Oxidation catalyst chamber 320 may be manufactured by the structure as illustrated in
Hereinafter, a process of reforming butane gas to hydrogen gas in the illustrated steam reforming device will be described.
Some butane gas supplied from the outside is reformed to hydrogen gas, and others are oxidized to supply calories required for the steam reforming reaction to the steam reforming device. The butane gas for heating flows through a gas inlet 356 for heating after being mixed with air, and is transferred to the oxidation catalyst chamber. The mixture of butane gas and air generates heat by oxidation reaction in oxidation catalyst chamber 320, and is converted into carbon monoxide.
The butane gas flows through a fuel inlet 352, and is heated by heat generated by an oxidation reaction in oxidation catalyst chamber 320, while passing through fuel flow pipe 362 encircling oxidation catalyst chamber 320. Water flows through a water inlet 354, and is heated by heat generated by an oxidation reaction in oxidation catalyst chamber 320, while passing through water flow pipe 364 encircling oxidation catalyst chamber 320, and thereby maintaining sufficient thermal energy for evaporation.
The heated water becomes steam by absorbing heat while moving through water 11 flow pipe 364, and the butane gas is preheated while moving through fuel flow pipe 362. The steam and the preheated butane gas are mixed in predetermined region A, and flows into reaction catalyst chamber 310 for the steam reforming.
The steam and the butane gas, flowing into reaction catalyst chamber 310 for the steam reforming, pass through the metal monolith installed inside steam reforming reaction catalyst chamber 310. A catalyst formed on passages inside the metal monolith helps the steam and the butane gas be reformed to hydrogen gas. Oxidation catalyst chamber 320, which surrounds reaction catalyst chamber 310, generates sufficient heat by an oxidation reaction, so that it can maintain temperature for the steam reforming. The hydrogen gas is emitted through an opening 358 installed upper of the reaction catalyst chamber 310.
Referring to
An effect to obtain a means at low cost to secure reaction temperature between the reaction catalyst and inside gas at the time of initial operation is provided by using the reaction vessel and the reaction device according to the present invention of the above structure.
Further, steam reforming reaction temperature required at the time of initial operation is rapidly secured by embodying the steam reforming device according to an idea of the present invention. Therefore, an effect to improve reforming efficiency is provided.
Preferred embodiments of the present invention have been disclosed herein and, although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.
For example, the reaction device of the present invention can be applicable to components constituting a general reformer such as a reforming reactor, a water gas shift unit and a preferential CO oxidation unit respectively. However, it is described by embodying that the reaction device is applied to the reforming reactor, which is difficult to embody because of its highest reaction temperature, in the embodiment of
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2007-0004001 | Jan 2007 | KR | national |
