Patent Application
20110008700
The present invention generally relates to a fluid diverter for use in fuel cell systems and more specifically relates to an adjustable diverter capable of directing the flow of fluids within the fuel cell system or directing fluids to and from the fuel cell system.
A fuel cell is a device which uses an electrochemical reaction to convert chemical energy stored in a fuel such as hydrogen or methane into electrical energy. In general, fuel cells include an anode to catalytically react with the fuel and a cathode in fluid communication with an oxidant such as air. The anode and cathode are disposed on opposing sides of an electrolyte material which conducts electrically charged ions therebetween. The electrolyte material and the design of the fuel cell determine the type and performance of the fuel cell. For example, Molten Carbonate Fuel Cells (MCFC) which operate at approximately 650° C. typically include an electrolyte which is a molten liquid during operation.
The anode and the cathode for MCFCs are typically porous nickel (Ni) catalysts which are involved in electrochemical reactions for the production of charged ions. The cathode reacts with oxygen supplied from the surrounding air. The anode reacts with hydrogen from a hydrogen-rich fuel supplied to the anode. As a result of the reaction at the anode, anode exhaust fluids, for example water and carbon dioxide, are generated and can be directed away from the anode. Typically, not all of the fuel supplied to the anode is converted into electrical power. Thus some of the unused fuel can travel with the anode exhaust fluids. The unused fuel can be consumed in another reaction which gives off heat. The heat can be used to pre-heat the oxygen and/or fuel supplied to the MCFC.
The present invention resides in a fuel cell system having a fuel cell module including a fuel cell stack. The fuel cell stack includes a cathode compartment having a cathode conduit extending from an inlet of the cathode compartment. The cathode conduit conveys a first fluid to one or more cathodes positioned in the cathode compartment. The fuel cell stack also includes an anode compartment having a fuel inlet conduit extending from an inlet of the anode compartment. The inlet conduit supplies fuel to one or more anodes positioned in the anode compartment. The anode compartment has an anode exhaust conduit extending from an outlet thereof, for conveying an anode exhaust fluid out of the anode compartment.
The fuel cell stack is positioned in an enclosure, which has a passage extending therethrough. At least a portion of the passage is in fluid communication with the anode exhaust conduit. The enclosure has diverter means positioned in the passage and/or the anode exhaust conduit. The diverter means is configured to divert the anode exhaust fluid from the anode exhaust conduit to the cathode compartment and/or the passage.
The present invention also resides in a fuel cell module wherein the diverter means includes a plug positioned in the passage for blocking flow of the anode exhaust fluid through the passage and directing the anode exhaust fluid to the cathode compartment.
The present invention also resides in a fuel cell module wherein the anode exhaust conduit includes a first opening defined by an edge. The anode exhaust conduit has an upstream portion positioned upstream of the first opening and a downstream portion positioned downstream of the first opening. The diverter means includes a diverter conduit having a first end and a second end. The first end is positioned in the anode exhaust conduit and spaced apart from the edge such that the diverter conduit and the downstream portion are in fluid communication with one another. The upstream portion is blocked from fluid communication with the downstream portion by an outside surface of the diverter conduit. The diverter means also includes an outer conduit having a mounting end. The mounting end sealingly engages a portion of the anode exhaust conduit adjacent to the edge. The second end of the diverter conduit extends into the outer conduit. There is a diverter outlet flow area located between an inside surface of the outer conduit and the outside surface of the diverter conduit. The diverter outlet flow area is in fluid communication with the upstream portion. The diverter outlet flow area is blocked by a seal positioned between the inside surface and the outside surface. The outer conduit has an outlet opening positioned between the seal and the mounting end.
The present invention also resides in a fuel cell module wherein the diverter device includes a fluid compressor, such as a blower. The fluid compressor has an inlet and an outlet portion. The fluid compressor is used for increasing pressure of the anode exhaust being conveyed through the fluid compressor. The inlet of the fluid compressor is in fluid communication with the anode exhaust conduit and the outlet is in fluid communication with the cathode compartment. In one embodiment, the fluid compressor is driven by driver means, for example, a variable speed drive motor.
Referring to
While the enclosure 20 is described as being a hollow cylindrical vessel 20V and having circular cover plates 24A, 24B, the present invention is not limited in this regard as enclosures and covers of any shape, including but not limited to box shape enclosures and rectilinear covers, can be employed without departing from the broader aspects of the present invention.
The electrical balance of plant module 14 includes electrical equipment (not shown) such as an inverter, power metering, switching equipment and a voltage transformer. The mechanical balance of plant module 16 includes equipment (not shown) needed to feed fuel, air and water to the fuel cell module 12, for preheating and humidifying the fuel and for receiving and treating exhaust fluids from the fuel cell module.
The cover plate 24B is shown having two electrical penetrations 25 extending therethrough. Wiring 25W extends into the fuel cell module 12 through the electrical penetrations. The wiring 25W provides the electrical communication between the fuel cell module 12 and the electrical balance of plant module 14. The cover plate 24B also has first through fourth passages 26A-26D extending therethrough. The first through third passages 26A-26C have respective conduits removably positioned thereon and extending to the mechanical balance of plant module 16, as described below. Use of the fourth passage 26D is described below. Forming the first through fourth passages 26A-26D in the cover plate 24B is a difficult operation that is generally conducted with appropriate machining tools, before installation of the cover plate on the cylindrical vessel 20V.
Referring to
An anode exhaust conduit 33 extends from the anode compartment 32 to a catalytic oxidizer 34. The catalytic oxidizer 34 has a catalyst (not shown) disposed therein. The anode exhaust conduit 33 provides fluid communication between the anode compartment 32 and the catalytic oxidizer 34 for conveying anode exhaust fluids including carbon dioxide, water, residual fuel and/or hydrogen not consumed by the anode 29, to the catalytic oxidizer. An air supply conduit 27B extends from the mechanical balance of plant module 16 to the catalytic oxidizer 34. The air supply conduit 27B provides fluid communication between the mechanical balance of plant module 16 and the catalytic oxidizer 34 for conveying air to the catalytic oxidizer 34.
During operation, the residual fuel, mainly hydrogen and carbon monoxide, in the anode exhaust fluids flow into the catalytic oxidizer 34 and react with oxygen on a catalyst in a chemical reaction which gives off heat. The heat is used to preheat the air which mixes with the anode exhaust fluids within the catalytic oxidizer 34.
The cathode 30 is positioned in a cathode compartment 35. A cathode supply conduit 36 is disposed between the cathode compartment 35 and the catalytic oxidizer 34. The cathode supply conduit 36 provides fluid communication between the cathode compartment 35 and the catalytic oxidizer 34 for conveying preheated air and anode exhaust fluids to the cathode 30 for reaction therewith. A cathode exhaust conduit 27C provides fluid communication between the cathode compartment 35 and the mechanical balance of plant module 16 for conveying cathode exhaust fluids to the mechanical balance of plant module for processing.
While the fuel cell system 18 is shown having one Molten Carbonate Fuel Cell (MCFC) 28 which includes an anode 29 and a cathode 30 disposed on opposing sides of an electrolyte matrix 31, the present invention is not limited in this regard as other configurations including but not limited to, multiple MCFCs configured in any number of stacks, one or more solid oxide fuel cells, one or more phosphoric acid fuel cells and one or more of another type of fuel cell, may be employed without departing from the broader aspects of the present invention.
Referring to
As illustrated in
The fourth passage 26D is defined by interior surfaces of an expansion joint 51 and another nipple 46, as described below. The fourth passage 26D penetrates the cover plate 24B in a predetermined position which is located to provide access to the duct portion 38 of the anode exhaust conduit 33. The fourth passage 26D and the cylindrical interior surface thereof are coaxial with the reference axis R. A tubular nipple 43 has one end thereof positioned in the fourth passage 26D and engaged with the cylindrical interior surface 42. A substantially round face plate 44, sized to fit on an opposite end of the tubular nipple 43, is secured to the opposite end of the tubular nipple. The face plate 44 has a second circular opening 45, defined by a diameter D2 which is approximately equal to the diameter of the passage 26D. The other nipple 46 has an inside diameter, about equal to the diameter D2 of the second circular opening 45. One end of the other nipple secured to the face plate 44. The other nipple 46 is positioned coaxially with the reference axis R. A mounting flange 47 extends radially outward from an opposite end of the other nipple 46.
While the tubular nipple 43, round face plate 44, the other nipple 46 and a mounting flange are described, the present invention is not limited in this regard, as other configurations including but not limited to those which utilize members having rectilinear cross sections and those utilizing threaded connections, can also be employed without departing from the broader aspects of the present invention. Although the fourth passage 26D is described as penetrating the cover plate 24B in a predetermined manner to provide access to the duct portion 38, the present invention is not limited in this regard, as other configurations such as but not limited to the fourth passage penetrating any portion of the cover plate 24A, on any portion of the cover plate 24B or on any portion of the cylindrical vessel 20V and/or the fourth passage being positioned to access any portion of the anode exhaust conduit and/or the anode compartment, can be employed without departing from the broader aspects of the present invention.
Referring to
As shown in
Referring to
The plug 54 diverts the anode exhaust fluids from exiting the fourth passage 26D. The plug 54 allows for operation of the fuel cell system 12 with the anode exhaust fluid AE being conveyed by the anode exhaust conduit 33, the duct portion 38, the spacer ring 49 and the pipe elbow 40, to the catalytic oxidizer 34. The plug 54 can be removed from the fourth passage 26D and replaced with another device, for example, another diverter when operating in the performance enhancing mode, as described below, with reference to
The fuel cell system of
While the fuel cell system 112 is described as including the fluid diverter 157 for use with the hydrogen recovery system 156, the present invention is not limited in this regard as the fluid diverter can be used for other purposes, including but not limited to: flowing hydrogen through the outlet 157Y of the fluid diverter 157, from the MCFC 128 anode compartment 132 during an initial conditioning operation of the MCFC 128 when a reducing atmosphere is desired to be maintained on the anode. This hydrogen can then be cooled, slightly compressed with a blower, and then returned to the anode compartment 132 to minimize hydrogen consumption during conditioning and improve the efficiency of the conditioning process.
The fluid diverter 157 also includes an internal assembly 162, a portion of which is positioned in the pipe tee 158, as described below. The internal assembly 162 is shown having a first pipe section 162A and a second pipe section 162B, coupled to one another by a tubular expansion joint 162C having a fluted longitudinal cross section. The first and second pipe sections 162A, 162B and the expansion joint 162C are coaxial with a reference axis R′. The circular edge 160A of the inwardly extending flange 160 is sealingly engaged with an outside surface 162D of the second pipe section 162B. An annular flow area 163 is defined by a space between the internal assembly 162 and the pipe tee 158.
The internal assembly 162 further includes two J-bolts 165 each slidingly and rotatably positioned in a pair of tabs 166A, 166B spaced apart from one another and extending inwardly from a portion of an inside surface 162E of the internal assembly corresponding to the first pipe section 162A. The J-bolts 165 are used to removably hold the internal assembly 162 in a predetermined position. A portion of each of the J-bolts 165 has a threaded section 165T initiating at a first end 165A of the J-bolt and terminating at a point on the J-bolt between the tabs 166A, 166B. A second end 165B of the J-bolt 165 has a J-shaped connector 167 secured thereto. Before installation of the fluid diverter 157 into the fourth passage 126D, distal ends of the respective J-shaped connectors 167 are rotated inwardly towards the reference axis R′ so that the J-shaped connectors can pass through the first circular opening 138D. Each of the threaded sections 165T have a nut 168 threaded thereon. The nut 168 and threaded section 165T are used to move the J-bolts 165 relative to the respective tabs 166A, 166B during installation and removal of the fluid diverter 157 to and from the fourth passage 126D.
Although the fluid diverter is described as including a pipe tee 158 and internal assembly 162, the present invention is not limited in this regard as other configurations, such as but not limited to, use of conduits with rectilinear cross sections and one passage with two or more pipes positioned adjacent to one another, can also be employed without departing from the broader aspects of the present invention. While the two J-bolts 165 are described as removably holding the internal assembly 162 in a predetermined position, the present invention is not limited in this regard as more than two J-bolts and other devices for removably holding the internal assembly in the predetermined position, including but not limited to, use of a threaded connection, a bayonet connection and springs can be employed without departing from the broader aspects of the present invention.
Referring to
Referring to
Also during operation, the MCFC 128 heats up to a temperature of about 650° C. resulting in a temperature differential between the MCFC and the enclosure 120. As a result of the differential temperature, thermal growth of the MCFC 128, cover plates 124A, 124B and the enclosure 120 differ. During operation, the expansion joints 151, 162C compress to compensate for the difference in thermal growth between the MCFC 128 and the enclosure 120 and/or the cover plates 124A, 124B.
The fuel cell system of
During operation, the drive unit 278 operates the pressurizing device 272 to control the differential pressure between the anode compartment 232 and the catalytic oxidizer 234 to minimize the pressure difference between the anode compartment 232 and the cathode compartment 235. This minimizes the leakage of anode gas from the anode inlet to the cathode inlet which minimizes fuel needed and maximizes operating efficiency. This is particularly valuable when effectiveness of the high temperature seal between the anode and cathode has been reduced due to age or other causes. Such pressurizing device may be incorporated after such a reduction is seal effectiveness is observed. The pressurizing device 272 establishes an appropriate magnitude of the differential pressure to maintain the flow of the anode exhaust to compensate for the leakage.
Although the present invention has been disclosed and described with reference to certain embodiments thereof, it should be noted that other variations and modifications may be made, and it is intended that the following claims cover the variations and modifications within the true scope of the invention.
