Patent Application
20120167577
The present disclosure is directed to gas turbine systems and processes. More specifically, the present disclosure is directed to systems and methods using CO2 for cooling turbine components.
In power generation systems, operational efficiencies are desired for meeting increased energy demand at lower costs. Carbon sequestration in power systems captures carbon dioxide from exhaust gases and stores it in the sequestration process. Capturing the carbon consumes substantial amounts of energy and reduces performance efficiency of known power systems.
In a known power generation system, a closed-loop cooling arrangement within a gas turbine is cooled with a non-electrically conductive liquid. A pump circulates the liquid and heat transfer is enhanced by an orifice placed within the loop that reduces pressure. The known system suffers from the drawback of not being able to provide carbon capture with desirable efficiency.
In another known power generation system, an open-loop cooling arrangement including nitrogen from an air separation unit is used. The system suffers from the drawback that it is only applicable for oxygen-based (gasifier) systems in integrated gasification combined cycle (IGCC) operations.
A gas turbine system and process that is more efficient and does not suffer from the drawbacks of the prior art would be desirable in the art.
In one embodiment, a gas turbine system includes a compressor component configured to compress fluid to form a compressed fluid stream, a combustor configured to receive at least a first portion of the compressed fluid stream and at least partially combust a syngas to form a combustor discharge stream, and a turbine component positioned to receive the combustor discharge stream and to form a turbine component stream. At least a second portion of the compressed fluid stream is directed to the turbine component stream. A cool CO2 stream directed from a CO2 capture system cools the turbine component stream. The cool CO2 stream is heated by the turbine component stream to form at least a heated CO2 stream. At least a portion of the heated CO2 stream transfers heat to the compressed fluid stream from the compressor to the combustor.
In one embodiment, a gas turbine system includes a compressor component configured to compress fluid to form a compressed fluid stream, a combustor configured to receive at least a first portion of the compressed fluid stream and at least partially combust a syngas to form a combustor discharge stream, and a turbine component positioned to receive the combustor discharge stream and to form a turbine component stream. At least a second portion of the compressed fluid stream is directed to the turbine component stream. A cool nitrogen stream directed from a second system cools the turbine component stream. The cool nitrogen stream is heated by the turbine component stream to form at least a heated nitrogen stream. At least a portion of the heated nitrogen stream transfers heat to the compressed fluid stream from the compressor to the combustor.
In one embodiment, a process includes providing a CO2 capture system comprising an absorber and a stripper for forming a cool CO2 stream, directing the cool CO2 stream to a turbine component, transferring heat from a turbine component stream in the turbine component to the cool CO2 stream to form at least a heated CO2 stream, and directing at least a portion of the heated CO2 stream through a heat exchanger to the CO2 capture system.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
Wherever possible, the same reference numbers will be used throughout the drawings to represent the same parts.
Provided is a gas turbine system and method that is more efficient and does not suffer from the drawbacks of the prior art. Embodiments of the present disclosure permit the disclosed systems and methods to be applied to simple and combined cycle IGCC operations, permit the disclosed systems and methods to incorporate CO2 capture processes into IGCC operations, permit the disclosed systems and methods to incorporate other systems into IGCC operations, permit increased efficiency by decreasing the amount of fuel required for reaching a predetermined firing temperature, permit increased efficiency by increasing an exhaust temperature being directed to a heat recovery steam generator, and permit lower cost installation, operation, and maintenance.
A cool CO2 stream 120 directed from a CO2 capture system 122 cools the turbine component stream 116. The cool CO2 stream 120 has a temperature of about 300° F. to about 600° F. or about 100° F. to about 400° F. lower in temperature than gas turbine compressor discharge air. In one embodiment, the cool CO2 stream 120 consists essentially of gaseous CO2. In another embodiment, the cool CO2 stream 120 includes CO2 at a concentration greater than that of air. The cool CO2 stream 120 is heated by the turbine component stream 116 to form at least a heated CO2 stream 124 (for example, having a temperature above about 1000° F.). A portion or all of the heated CO2 stream 124 transfers heat to the compressed fluid stream 108. In one embodiment, the cool CO2 stream 120 is directed to the turbine component stream 116 without assistance of a pump.
In one embodiment, the gas turbine system 100 includes a heat exchanger 134. The heat exchanger 134 is positioned to transfer heat from the heated CO2 stream 124 to the first portion 108 of the compressed CO2 stream 104.
As will be appreciated, multiple stages of the compressor component 102 and the turbine component 114 permit any suitable portions of the compressed fluid stream 104 and/or the cool CO2 stream 120 to exchange heat with the turbine component stream 116 and/or the combustion discharge stream 112 at a plurality of pressure and/or temperature relationships. Any suitable number of stages may be included. For example, in one embodiment, eighteen compressor stages are included. In a further embodiment, the first compressor stage 136 is the ninth stage, the second compressor stage 138 is the thirteenth stage, and the third compressor stage 140 is the eighteenth stage. One or more portions of the compressed fluid stream 104 may be directed from multiple compressor stages to the turbine component 114 thereby cooling the turbine component stream 116. In one embodiment, the third compressor stage 140 directs the second portion 118 of the compressed fluid stream 104 to a second turbine stage 142 in the turbine component 114.
The turbine component 114 includes a first turbine stage 144 and a second turbine stage 142. In one embodiment, the turbine component 114 further includes a third turbine stage 146. Any suitable number of turbine stages may be included. One or more turbine stages of the turbine component 114 is positioned to receive the combustor discharge stream 112 to form the turbine component stream 116. The second portion 118 of the compressed fluid stream 104 directed to the turbine component 114 cools the turbine component stream 116. In one embodiment, the second compressor stage 138 directs the second portion 118 of the compressed fluid stream 104 to the first turbine stage 144, the second turbine stage 142, the third turbine stage 146, or combinations thereof.
The turbine component stream 116 is further cooled by the cool CO2 stream 120 in the first turbine stage 144. In one embodiment, the cool CO2 stream 120 is directed to the first turbine stage 144, heat is transferred from the turbine component stream 116 in the first turbine stage 144 to the cool CO2 stream 120 to form at least the heated CO2 stream 124, and at least a portion of the heated CO2 stream 124 is directed through the heat exchanger 134 to the CO2 capture system 122. In a further embodiment, the turbine component 114 is arranged and disposed to receive the combustion discharge stream 112 from the combustor 106 and the heat exchanger 134 is arranged and disposed to transfer heat from the heated CO2 stream 124 to at least the portion 108 of the compressed fluid stream 104 directed to the combustor 106.
In another embodiment, CO2 is used for closed loop cooling of the turbine component 114. In this embodiment, a closed loop CO2 stream includes the heated CO2 stream 124 and the cool CO2 stream 120. For example, the combustion discharge stream 112 is directed to the turbine component 114 to form the turbine component stream 116, the turbine component stream 116 is cooled with a cooled portion 120 of a closed loop CO2 stream thereby forming the heated portion 124 of the closed loop CO2 stream, and the compressed fluid stream 104 is heated by the heated portion 124 of the closed loop CO2 stream. In a further embodiment, a portion of the cooled portion 120 of the closed loop CO2 stream is directed from the carbon capture system 122 and at least a portion of the heated portion 124 of the closed loop CO2 stream is directed to the carbon capture system 122.
In one embodiment, the gas turbine system 100 further includes a heat recovery steam generator 126. In this embodiment, the turbine component stream 116 is directed to the heat recovery steam generator 126. In one embodiment, a portion 150 or all of the heated CO2 stream 120 is directed to the heat recovery steam generator 126. A portion of an outlet stream 148 from the heat recovery steam generator 126 is directed to the CO2 capture system 122 for CO2 capture/sequestration.
A cool nitrogen stream 320 directed from an air separation unit 322 or other suitable process cools the turbine component stream 116. The cool nitrogen stream 320 is heated by the turbine component stream 116 to form at least a heated nitrogen stream 324 (for example, having a temperature above about 1000° F.). A portion or all of the heated nitrogen stream 324 transfers heat to the compressed fluid stream 108.
In one embodiment, the gas turbine system 100 includes a heat exchanger 134. The heat exchanger 134 is positioned to transfer heat from the heated nitrogen stream 324 to the first portion 108 of the compressed fluid stream 104.
As will be appreciated, multiple stages of the compressor component 102 and the turbine component 114 permit any suitable portions of the compressed fluid stream 104 and/or the cool nitrogen stream 320 to exchange heat with the turbine component stream 116 and/or the combustion discharge stream 112 at a plurality of pressure and/or temperature relationships.
The turbine component stream 116 is further cooled by the cool nitrogen stream 320 in the first turbine stage 144. In one embodiment, the cool nitrogen stream 320 is directed to the first turbine stage 144, heat is transferred from the turbine component stream 116 in the first turbine stage 144 to the cool nitrogen stream 320 to form at least the heated nitrogen stream 324, and at least a portion of the heated nitrogen stream 324 is directed through the heat exchanger 134 to the heat recovery steam generator 126. In a further embodiment, the first turbine stage 144 is arranged and disposed to receive the combustion discharge stream 112 from the combustor 106 and the heat exchanger 134 is arranged and disposed to transfer heat from the heated nitrogen stream 324 to at least the portion 108 of the compressed fluid stream 104 directed to the combustor 106.
While only certain features and embodiments of the invention have been shown and described, many modifications and changes may occur to those skilled in the art (for example, variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (for example, temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described (i.e., those unrelated to the presently contemplated best mode of carrying out the invention, or those unrelated to enabling the claimed invention). It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.
