Patent Application
20120204573
The present invention relates generally to a system and method for producing a hydrogen enriched fuel for subsequent combustion or distribution. In particular embodiments of the present invention, a fuel reformer is integrated with a gas turbine to enhance the overall efficiency of the integrated system.
Gas turbines are widely used in industrial and power generation operations. Various reformers may be used to produce hydrogen enriched fuel for the gas turbine or other uses. For example, a catalytic partial oxidation (CPDX) or steam methane reformer (SMR) may combine steam, a catalyst such as nickel or a precious metal, and fuel such as natural gas or methane to produce hydrogen. The fuel reformer may be integrated with the gas turbine to produce an integrated system having an enhanced overall efficiency. Specifically, U.S. Pat. No. 7,076,957, assigned to the same assignee as the present invention, describes a fluid heating and gas turbine integration method in which the gas turbine supplies exhaust gases to the fuel reformer to enhance the thermodynamic efficiency of the combined gas turbine and fuel reformer.
Although supplying the gas turbine exhaust to the fuel reformer improves the thermodynamic efficiency of the combined gas turbine and fuel reformer, continued improvements in the design and integration of a fuel reformer with a gas turbine would be useful. Specifically, the fuel reformer produces a high temperature exhaust stream having substantial amounts of energy, and an integrated system that can capture or utilize more of the energy from the high temperature exhaust stream from the fuel reformer may further enhance the thermodynamic efficiency of the combined gas turbine and fuel reformer.
Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the invention.
One embodiment of the present invention is a system for producing a hydrogen enriched fuel. The system includes a gas turbine comprising a compressor, a combustor connected downstream of the compressor, and a turbine connected downstream of the combustor. A fuel reformer is connected between the compressor and the combustor. The fuel reformer comprises an inlet connected to the compressor and an outlet connected to the combustor, and the fuel reformer produces the hydrogen enriched fuel.
Another embodiment of the present invention is a gas turbine that includes a compressor that produces a compressed working fluid. A fuel reformer downstream of the compressor receives a first portion of the compressed working fluid from the compressor and produces a hydrogen enriched fuel and an exhaust stream. A combustor downstream of the compressor and the fuel reformer receives the exhaust stream from the fuel reformer and produces combustion gases. A turbine downstream of the combustor receives the combustion gases from the combustor.
Embodiments of the present invention may also include a method for producing a hydrogen enriched fuel. The method includes compressing a working fluid with a compressor to produce a compressed working fluid and diverting a first portion of the compressed working fluid to a fuel reformer. The method further includes mixing a fuel with the compressed working fluid in the fuel reformer to produce the hydrogen enriched fuel and an exhaust stream and flowing the exhaust stream to a combustor.
Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.
A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:
Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention.
Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
Various embodiments of the present invention integrate a fuel reformer with a gas turbine to produce an integrated thermodynamic cycle with enhanced overall efficiency. In specific embodiments, the fuel reformer may receive a compressed working fluid and/or steam from the gas turbine to generate a hydrogen enriched fuel. The hydrogen enriched fuel may then be supplied to the gas turbine, recirculated back to the reformer, and/or collected for other uses. In addition, the fuel reformer may be integrated with the gas turbine to provide a high temperature exhaust stream to the gas turbine, specifically to one or more combustors in the gas turbine, to more efficiently capture or utilize energy produced by the fuel reformer.
Ambient air 22 enters the compressor 16, and stationary vanes and rotating blades in the compressor 16 progressively impart kinetic energy to the working fluid (air) to produce a compressed working fluid 24 at a highly energized state. The compressed working fluid 24 exits the compressor 16 and flows through nozzles in the combustor(s) 18 where it mixes with a fuel 26 and ignites to generate combustion gases 28 having a high temperature and pressure. The combustion gases 28 flow to the turbine 20 where they expand to produce work. For example, expansion of the combustion gases 28 in the turbine 20 may rotate a shaft 30 connected to a generator 32 to produce electricity.
The combustion gases 28 exit the turbine 20, and, if released immediately to the environment, would result in wasted energy generated by the gas turbine 12 that does not produce work. Therefore, the heat recovery system 14 connected downstream of the turbine 20 receives the combustion gases 28 from the turbine 20 to extract additional energy from the combustion gases 28. Specifically, the heat recovery system 14 generally comprises a steam generator 34, a steam turbine 36, and a condenser 38. The steam generator 34 receives the combustion gases 28 from the turbine 20 to heat water to generate steam 40. The steam 40 then flows through the steam turbine 36 where it expands to produce work. For example, expansion of the steam 40 in the steam turbine 36 may rotate a shaft 42 connected to a generator 44 to produce electricity. The shaft 42 and generator 44 may be the same shaft 30 and generator 32 connected to the gas turbine 12, or the gas turbine 12 and heat recovery system 14 may operate using separate shafts and generators. The condenser 38 downstream of the steam turbine 36 condenses the steam 40 to condensate 46, and the condensate 46 returns to the steam generator 34, and the cycle repeats. The heat recovery system 14 thus captures energy from the combustion gases 28 before they are eventually released to the environment, thus increasing the overall efficiency of the combined cycle power plant 10.
As shown in
As previously described, the exhaust stream 66 from the fuel reformer 54 flows to the combustor 18. In this manner, the system 50 utilizes the energy in the high temperature exhaust stream 66 from the fuel reformer 54 in the combustor 18. As shown in
The system 50 shown in
The method may further include flowing the exhaust stream 66 to the combustor 18 to efficiently utilize the high temperature exhaust stream 66 to produce the combustion gases 28. If desired, the second portion of the compressed working fluid 80 may also be diverted to the combustor 18 to mix with the high temperature exhaust stream 66 prior to or after entry into the combustor 18. In this manner, the fuel reformer 54 may be integrated with the combined cycle power plant 10 to enhance the overall thermodynamic efficiency of the system 50.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
