Abstract:
A turbine combustion air system includes a recuperator and a multi-zone combustor for accepting multiple combustion air streams at multiple temperatures.

Description:
PRIORITY CLAIM 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 61/160,301 for RECUPERATOR BYPASS TO COMBUSTOR PRIMARY ZONE filed Mar. 14, 2009. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a Brayton cycle machine. In particular, a combustion turbine includes a new and useful combustion air system. 
         [0004]    2. Discussion of the Related Art 
         [0005]    Combustion turbines typically have combustors located between a turbine section and a compressor section. These combustors typically receive combustion air from the compressor section and fuel from a fuel source. Fuel and combustion air mixed in the combustor provide a flammable mixture that is ignited to produce hot gases that expand across and drive the turbine section. 
         [0006]    Efficiency improvements in combustion turbines include recovery of energy from the hot gases exhausted from the turbine section. Small combustion turbines with relatively low compressor outlet pressures and air flow rates have used recuperators to capture exhaust energy to preheat compressor discharge air. Large combustion turbines with relatively high compressor outlet pressures and air flow rates typically add a Rankine cycle machine to utilize recovered exhaust gas energy as this avoids large pressure differentials across large heat exchanger surfaces. 
         [0007]    Combustion air for turbine combustors is typically supplied directly from the compressor in large turbines. In smaller turbines, the combustion air is typically supplied either directly from the compressor or, where there is a recuperator, from a high pressure recuperator outlet. 
       SUMMARY OF THE INVENTION 
       [0008]    In the present invention, a combustion turbine has a combustion air system including a recuperator and a multi-zone combustor. In an embodiment, the turbine combustion air system comprises a compressor and combustor connected via a first fluid circuit. An included recuperator has a heating passage and a cooling passage with the heating passage forming a part of the first fluid circuit for preheating compressor discharge air. The first fluid circuit is operable to deliver pre-heated air to a combustor dilution air inlet and a second fluid circuit connects the compressor and the combustor. The second fluid circuit bypasses the heating passage and operates to deliver air to a combustor primary air inlet. A third fluid circuit connects the combustor and the cooling passage and a turbine forms a part of the third fluid circuit for expanding combustion products such that the third fluid circuit is operable to deliver turbine exhaust to a cooling passage inlet. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present invention is described with reference to the accompanying figures. These figures, incorporated herein and forming part of the specification, illustrate embodiments of the invention and, together with the description, further serve to explain its principles enabling a person skilled in the relevant art to make and use the invention. 
           [0010]      FIG. 1  shows a prior art combustion turbine system. 
           [0011]      FIG. 2  shows a prior art combustion turbine system with a recuperator. 
           [0012]      FIG. 3  is a first combustion turbine system in accordance with the present invention. 
           [0013]      FIG. 4A  is a second combustion turbine system in accordance with the present invention. 
           [0014]      FIG. 4B  is a third combustion system in accordance with the present invention. 
           [0015]      FIG. 5  is a fourth combustion turbine system in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    The disclosure provided in the following pages describes examples of some embodiments of the invention. The designs, figures, and description are non-limiting examples of the embodiments they disclose. For example, other embodiments of the disclosed device and/or method may or may not include the features described herein. Moreover, disclosed advantages and benefits may apply to only certain embodiments of the invention and should not be used to limit the disclosed invention. 
         [0017]      FIG. 1  shows a prior art combustion turbine system without turbine exhaust gas heat recovery  100 . Arranged as an open cycle machine, the combustion turbine includes a compressor  104 , a combustor  108 , a turbine  112 , and a first interconnecting shaft  116  for transferring turbine work to the compressor. The combustion turbine drives a load such as an electric generator  120  via a second interconnecting shaft  118  coupling the compressor to the load. 
         [0018]    The combustor  108  is located between the compressor  104  and the turbine  112 . Air drawn from a compressor inlet  102  is compressed and discharged to a compressor outlet  106  that is coupled to the combustor. A fuel supply line  111  provides fuel to the combustor. As used herein, the term inlet refers to one or more of a device inlet and/or a line coupled with the device inlet. Similarly, the term outlet refers to one or more of a device outlet and/or a line coupled with the device outlet. 
         [0019]    Combustion of a fuel/air mixture produces gaseous combustion products that flow from the combustor  108  to the turbine  112  through a turbine inlet  110 . Combustion gases expand as they pass through the turbine and the expanded gases leave the turbine through a turbine exhaust  114 . 
         [0020]      FIG. 2  shows a prior art combustion turbine system with turbine exhaust gas heat recovery  200 . Arranged as an open cycle machine, the combustion turbine includes a compressor  104 , a combustor  108 , a turbine  112 , a heat exchanger or recuperator  202 , and a first interconnecting shaft  116  for transferring turbine work to the compressor. The combustion turbine drives a load such as an electric generator  120  via a second interconnecting shaft  118  coupling the compressor to the load. 
         [0021]    A combustor  108  is located between the recuperator  202  and the turbine  112 . Air drawn from a compressor inlet  102  is compressed and discharged to a high pressure inlet  106  of the recuperator. Air heated by the recuperator in recuperator heating passages  210  is discharged at a recuperator high pressure outlet  206  that is coupled to the combustor  108 . A fuel supply line  111  provides fuel to the combustor. 
         [0022]    Combustion of a fuel/air mixture produces gaseous combustion products that flow from the combustor  108  to the turbine  112  through a turbine inlet  110 . Combustion gases expand as they pass through the turbine and the expanded gases leave the turbine through a turbine exhaust  114  that is coupled to a low pressure inlet of the recuperator. Combustion gases cooled by the recuperator in recuperator cooling passages  208  are discharged at a recuperator low pressure outlet  204 . 
         [0023]      FIG. 3  shows a combustion turbine system with turbine exhaust gas heat recovery and a multi-zone combustor in accordance with an embodiment of the present invention  300 . The combustion turbine system includes a compressor  250 , a multi-zone combustor  252 , a turbine  254 , and a heat recovery device  256 . 
         [0024]    Gas enters the compressor  250  via a compressor gas inlet  251 . Compressed gas from the compressor supplies the heat recovery device  256  via a first line  261  and optionally supplies the multi-zone combustor  252  via a second line  262 . The turbine  254  receives combustion products from the multi-zone combustor via a third line  263  and exhausts to the heat recovery device via a fourth line  264 . Cooled combustion products leave the heat recovery device via an exhaust line  265 . In various embodiments, other devices such as flow restrictors and heat exchangers are interposed in one or more lines. 
         [0025]    In various embodiments, other equipment such as heat exchangers, filters, valves, and bleeds is associated with one or more of the compressor inlet, compressor discharge, turbine inlet and turbine exhaust. Exemplary turbine system arrangements including one or more of these items of equipment are found below. 
         [0026]      FIG. 4A  shows a combustion turbine system with turbine exhaust gas heat recovery and a multi-zone combustor in accordance with an embodiment of the present invention  400 A. Arranged as an open cycle machine, the combustion turbine includes a compressor  104 , a combustor  302 , a turbine  112 , a heat exchanger or recuperator  202 , and a first interconnecting shaft  116  for transferring turbine work to the compressor. 
         [0027]    In various embodiments, the combustion turbine drives a load such as an electric generator  120  via a second interconnecting shaft  118  coupling the compressor  104  to the load. In other embodiments, an interconnecting shaft couples the turbine to a load. 
         [0028]    In various embodiments, turbine  112  includes multiple turbines at least one of which has no direct/shaft connection to the compressor  104 . Such “free-turbine” arrangements are commonly found in aircraft engines. 
         [0029]    Combustor  302  is a multi-zone combustor including a primary air zone  304  and a dilution air zone  306 . The primary air zone is capable of receiving combustion air from a primary zone air inlet  312  and the dilution air zone is capable of receiving combustion air from a dilution air zone inlet  308 . 
         [0030]    Air drawn from a compressor inlet  102  is compressed and discharged via a compressor discharge  310  to a recuperator high pressure inlet  106  and the combustor primary zone inlet  312 . Air heated by the recuperator in recuperator heating passages  210  flows to the combustor  302  via the combustor dilution air inlet  308 . A fuel supply line  111  and fuel control valve  314  provide fuel to the combustor. 
         [0031]    Ignition of a fuel/air mixture in the combustor primary zone produces gaseous combustion products that mix with dilution air from the dilution air zone  306 . These gases flow from the combustor  302  to the turbine  112  through a turbine inlet  110 . Combustion gases expand as they pass through the turbine and the expanded gases leave the turbine through a turbine exhaust  114  that is coupled to a low pressure inlet of the recuperator. Combustion gases cooled by the recuperator in recuperator cooling passages  208  are discharged at a recuperator low pressure outlet  204 . 
         [0032]      FIG. 4B  shows a combustion turbine system with turbine exhaust gas heat recovery and a multi-zone combustor in accordance with an embodiment of the present invention  400 B. Arranged as an open cycle machine, the combustion turbine includes a compressor  104 , a combustor  302 , a turbine  112 , a heat exchanger or recuperator  202 , and a first interconnecting shaft  116  for transferring turbine work to the compressor. 
         [0033]    In various embodiments, the combustion turbine drives a load such as an electric generator  120  via a second interconnecting shaft  118  coupling the compressor  104  to the load. In other embodiments, an interconnecting shaft couples the turbine  112  to a load. 
         [0034]    In various embodiments, turbine  112  includes multiple turbines at least one of which has no direct/shaft connection to the compressor  104 . Such “free-turbine” arrangements are commonly found in aircraft engines. 
         [0035]    Combustor  302  is a multi-zone combustor including a primary air zone  304  and a dilution air zone  306 . The primary air zone is capable of receiving combustion air from a primary zone air inlet  338  and the dilution air zone is capable of receiving combustion air from a dilution air zone inlet  308 . 
         [0036]    An air supply provides air to recuperator passages  210  via recuperator air inlet  332  and to the combustor primary zone  304  via primary zone inlet  338 . In some embodiments the air supply is ambient air such that the combustor  302  operates at a pressure below ambient air pressure. In an embodiment, the air is supplied from a fan discharge at a pressure above ambient air pressure. 
         [0037]    Air heated by the recuperator in recuperator heating passages  210  flows to the combustor  302  via the combustor dilution air inlet  308 . A fuel supply line  111  and fuel control valve  314  provide fuel to the combustor. 
         [0038]    Ignition of a fuel/air mixture in the combustor primary zone produces gaseous combustion products that mix with dilution air from the dilution air zone  306 . These gases flow from the combustor  302  to the turbine  112  through a turbine inlet  110 . Combustion gases expand as they pass through the turbine and the expanded gases leave the turbine through a turbine exhaust  114  that is coupled to recuperator cooling passages  208 . Combustion gases cooled by the recuperator in the recuperator cooling passages flow to a compressor  104  via a compressor inlet  334 . Pressurized combustion gases leave the compressor via a compressor discharge  336 . In some embodiments, the compressor discharges combustion gases directly to ambient. In an embodiment, the discharge is coupled to an inlet of a fan. 
         [0039]      FIG. 5  shows a combustion turbine system with turbine exhaust gas heat recovery and a multi-zone combustor  500 . In this embodiment, primary air is available from any of a compressor discharge  310 , a recuperator heating passage outlet  410 , and an auxiliary air source  420 . Respective control valves  402 ,  404 , and  406  enable selection of varying amounts of air from each source. 
         [0040]    In an operating mode, valves  402  and  404  are closed while valve  406  is open such that auxiliary air is supplied from an auxiliary source. Auxiliary sources include auxiliary compressors, air tanks, and air available from a truck braking system. For example, where truck braking system air is warmer than ambient air, this operating mode provides more favorable conditions for combustion turbine starting. 
         [0041]    In another operating mode, valves  402  and  406  are closed while valve  404  is open such that primary air is pre-heated air supplied from the recuperator  202 . For example, where combustion turbine load is reduced, this operating mode provides increased efficiency and reduced environmental impact through increased waste heat recovery and reduced carbon monoxide and unburned hydrocarbon emissions. 
         [0042]    In yet another operating mode, valves  406  and  404  are closed while valve  402  is open such that primary air bypasses the recuperator  202 . For example, where combustion turbine load is moderate to high, this operating mode provides reduced nitrous oxide (“NOx”) emissions. 
         [0043]    In operation, combustion of fuel in the combustor  302  provides hot, high pressure gases to the turbine inlet  110 . Expansion of these gases across the turbine rotates the turbine, compressor, and load via interconnecting shafts  116 ,  118 . In the case the load is an electric generator, electrical interconnection of the generator with electric power consumers provides a means for utilizing the generated power. 
         [0044]    Where it is desirable to operate a combustion turbine system at high efficiency while lowering nitrous oxide (NOx) emissions, arrangements including a recuperator and a multi-zone combustor offer advantages. Because heated air is available from the recuperator heated air outlet  308  and relatively cool air is available from the compressor discharge  310  or air supply via recuperator air inlet  332 , a multi-zone combustor can utilize the cool air in a primary zone  304  while maintaining high efficiency through use of hot air in a dilution zone  306 . 
         [0045]    While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to those skilled in the art that various changes in the form and details can be made without departing from the spirit and scope of the invention. As such, the breadth and scope of the present invention should not be limited by the above-described exemplary embodiments, but should be defined only in accordance with the following claims and equivalents thereof.