Abstract:
The present invention discloses a novel modular cooling system for cooling an air injection system where the cooling system is configured to conform generally to the foot print of the air injection system. The cooling system utilizes a plurality of coolers through which coolant from the air injection system passes prior to being recirculated back to the air injection system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application Ser. No. 62/309,694 filed on Mar. 17, 2016, which is hereby incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    This invention relates generally to electrical power systems, including generating, efficiency, and regulation capacity of a gas turbine, and more specifically to an air cooling system for cooling a continuous air injection power augmentation system. 
       BACKGROUND OF THE INVENTION 
       [0003]    Currently, marginal energy, or peak energy, is produced mainly by gas turbine engines, operating either in a simple cycle or a combined cycle configuration. As a result of load demand profile, gas turbine engines are cycled up during periods of high demand and cycled down, or turned off, during periods of low demand. In many areas of the world, less efficient simple cycle gas turbine engines are used instead of more efficient combined cycle gas turbine engines. This is due to the lack of available water typically required for combined cycle plant operation and high peak loads. Furthermore, even in areas of the world with high demand for more power, simple cycle gas turbines are often used due to high fuel prices. 
         [0004]    The Applicant has developed and produced an air injection system, commonly referred to as TurboPHASE®, which is capable of increasing the base load and peak load capacities of new and existing gas turbines while also improving efficiency. Applicant&#39;s air injection system, when applied to a fleet of gas turbines operating on liquid fuel would result in a fleet efficiency improvement of 3% during off peak periods and 5% during peak periods. However, one significant challenge for the air injection system is air cooling the system at power plants that do not have water. 
         [0005]    The air injection system utilizes an internal cooling circuit for cooling the major components of the air injection system, including a fueled engine, an intercooled multistage compressor, and a lube oil system. Typically, a water glycol system cools each of the components with a dedicated heat exchanger that is internal to the air injection system. One challenge is to develop a cooling system for the air injection system that also works in hot climates, as traditional intercooled compressors utilize a water cooling system. 
         [0006]    One key element of the air injection system is the modular nature of the system. The air injection system typically has a footprint, or occupying space, of a standard 40 foot shipping container or less, making it very easy logistically to install or move to an alternate location. Furthermore, the ancillary equipment required to support the air injection system, including air piping, air vent valves, air injection valves, recuperator, silencers, auxiliary air supply system and the gas fuel control system is typically mounted on the roof of the air injection system, so as to maintain the overall footprint of the system and its modular nature. 
         [0007]    Applying air cooling systems to an intercooled compressor introduces challenges due to the low temperature desired by the intercooling process. As one skilled in the art can appreciate, the lower the coolant temperature available for intercooling a multistage compression process, the more efficient and less power the multistage intercooled compressor requires for the same air flow and pressure output. On a fueled engine, the coolant temperature on the hot side of the heat exchanger, inside the radiator, is typically about 200 degree Fahrenheit (deg. F.) and the air temperature outside, even in desert-type conditions is much cooler, resulting in a large thermal gradient to promote heat transfer to the air. Therefore, a radiator type cooling system for the engine works extremely well and is minimal size, even in extremely hot conditions. However, intercooling coolant temperatures are typically 80 deg. F. to 100 deg. F. and are typically cooled with water from open cooling towers or a natural water source such as from large water bodies like lakes, rivers or oceans. These water coolant sources are typically cooler than ambient air conditions, and even in extremely hot ambient conditions, can typically provide cooling sufficient to meet the 80 deg. F. to 100 deg. F. requirement. The maximum temperature of about 100 deg. F. is critical because this coolant is not only used to cool the interstage air as it is compressed, but it is typically used to cool the lube oil system in the compressor, which typically has a temperature limit of about 130 deg. F. 
       SUMMARY 
       [0008]    The present invention provides several options, depending on specific plant needs, to improve the efficiency and power output of a plant at low loads, and to reduce the lower limit of power output capability of a gas turbine while also increasing the upper limit of the power output of the gas turbine, thus increasing the capacity and regulation capability of a new or existing gas turbine system. 
         [0009]    One aspect of the present invention relates to methods and systems that allow an air injection power augmentation system for a gas turbine engine to provide additional power by utilizing an air cooled system. 
         [0010]    Another aspect of the present invention relates to methods and systems that allow an air injection power augmentation system for a gas turbine engine to provide additional power utilizing a combined air cooled and chilling system. 
         [0011]    Yet another aspect of the present invention relates to methods and systems that allow an air injection power augmentation system for a gas turbine engine to provide additional power by utilizing a combined air cooled and chilling system or a modular air cooled system. 
         [0012]    In an embodiment of the present invention, a cooled compressed air generating system is provided comprising an intercooled compressor, a reciprocating engine powering the intercooled compressor system, and a multi-cooler air cooling system. The intercooled compressor system comprises a multi-stage compressor, an intercooler, and a lube oil system, while the multi-cooler air cooling system comprises coolers for the reciprocating engine and the intercooled compressor arranged in a parallel configuration. 
         [0013]    In yet another embodiment of the present invention, an arrangement of compressed air systems and corresponding air cooling systems are provided where the compressed air systems are arranged in parallel with the corresponding air cooling systems also arranged in parallel, but spaced differently than the compressed air systems. 
         [0014]    In another embodiment of the present invention, a cooled compressed air generating system is provided comprising an intercooled compressor, a driving mechanism for powering the intercooled compressor system, and a multi-cooler air cooling system. The intercooled compressor system comprises a multi-stage compressor, an intercooler, and a lube oil system, while the multi-cooler air cooling system comprises coolers for the driving mechanism and the intercooled compressor arranged in a parallel configuration. 
         [0015]    In yet another embodiment of the present invention, a cooled compressed air generating system is provided comprising an intercooled compressor, a reciprocating engine powering the intercooled compressor system, and a multi-cooler air cooling system. The intercooled compressor system comprises a multi-stage compressor, an intercooler, and a lube oil system, while the multi-cooler air cooling system comprises coolers for the reciprocating engine and the intercooled compressor with at least one of the coolers for the reciprocating engine being in series with the cooler for the intercooled compressor. 
         [0016]    The present invention provides an ability to increase the power output of the gas turbine engine with a supplemental air injection system that is cooled with ambient air, thereby eliminating the need for an external water cooling source. 
         [0017]    The present invention also provides the ability to maintain a modular nature of the air injection system while providing a stand-alone air cooling system for the air injection system. 
         [0018]    Yet another advantage of the present invention is the ability to maintain the same footprint of the air injection system while providing a stand-alone air cooling for the air injection system. 
         [0019]    Another advantage of the present invention is the ability to control the coolant temperature to the compressor lube oil cooling system. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0020]    The present invention is described in detail below with reference to the attached drawing figures, wherein: 
           [0021]      FIG. 1  is a schematic drawing of an embodiment of the present invention having a compressed air generating system with a fueled engine driving the air injection system, where the air injection system is air cooled through parallel cooling circuits. 
           [0022]      FIG. 2  is a schematic drawing of an embodiment of the present invention having a compressed air generating system having a fueled engine driving the air injection system, where the air injection system is cooled in a series of circuits. 
           [0023]      FIG. 3  is a schematic drawing of an embodiment of the present invention having a compressed air generating system with a fueled engine driving the air injection system which is air cooled with the engine and compressor cooling circuits arranged in parallel. 
           [0024]      FIG. 4  is a schematic drawing of an embodiment of the present invention having a compressed air generating system driven by a fueled engine and which is air cooled with the engine and compressor cooling circuits being in parallel and the compressor lube oil cooling circuit is accomplished with an auxiliary cooler. 
           [0025]      FIG. 5  is a schematic drawing of an embodiment of the present invention depicting a layout of a series of air injection systems and associated cooling systems with a fueled engine driving the supplemental compressor that is air cooled where the air cooler is arranged in a modular fashion above the compressed air generating system such that multiple systems can be located adjacent to each other. 
           [0026]      FIG. 6  is a schematic drawing of an embodiment of the present invention in which a cooling circuit for the engine and the multi-stage compressor pass through a common circuit. 
           [0027]      FIG. 7  is a schematic drawing of an embodiment of the present invention in which a cooling circuit for the engine and the multi-stage compressor operate in parallel. 
           [0028]      FIG. 8  is a schematic drawing of an embodiment of the present invention in which the cooling circuits for the engine and the multi-stage compressor are in parallel. 
           [0029]      FIG. 9  is a schematic drawing of an embodiment of the present invention in which the cooling circuits for an engine high temperature circuit and multi-stage compressor are in parallel while the engine low temperature circuit is cooled with compartment ventilation air. 
           [0030]      FIG. 10  is a perspective view of an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    The present invention will now be described with respect to  FIGS. 1-10 . Referring first to  FIG. 1 , a fuel driven air compression system  159  and an air cooling system  120  for cooling the fuel driven air compression system  159  are shown. The fuel driven air compression system  159  and the air cooling system  120  are configured to be used at a gas turbine plant for air injection power augmentation of the gas turbine engine. 
         [0032]    The fuel driven air compression system  159 , generally referred to in the industry as TurboPHASE®, comprises an engine  150  connected to an intercooled compressor  151  by way of shaft  152 . The intercooled compressor  151  comprises three major systems, a compressor  153 , an intercooler  154  that cools the air between stages of the compressor  153 , and a compressor lube oil cooler  179 . As one skilled in the art can appreciate, an electric motor could be used to drive the compressor  153 . 
         [0033]    The air cooling system  120  comprises three major components—a Low Temperature (LT) cooler  121 , a High Temperature (HT) cooler  122 , and the compressor intercooling water cooler  123 . These three cooling circuits provide the necessary cooling for the intercooled compression system  159 . 
         [0034]    The engine  150 , which can be a fueled engine, has a LT circuit to precondition the air within the engine to a specific temperature. This process is important for the engine  150  to maintain low emissions under a wide range of ambient conditions. The LT circuit consists of an LT cooler  121  that is supplied with a liquid coolant to be cooled through an LT supply line  141  from the engine  150 . A fan  131  pulls air through the air cooling system  120  such that ambient air is passed over the LT cooler  121  and the liquid coolant is cooled by the air that is passed by the LT cooler  121  and then returned to the engine  150  through the LT return line  142 . The LT cooling requirement is typically much less than and at a lower temperature (about 150 deg. F.) than the High Temperature (HT) circuit, and therefore is arranged upstream of the HT cooler  122 . 
         [0035]    In order to save space and eliminate the need for an additional fan, the HT cooler  122  is arranged in vertical orientation relative to the LT cooler  121 . The HT cooler  122  is used to cool the engine jacket of the engine  150  and is at a much higher temperature, typically 200 deg. F. Although the air temperature increases after passing the LT cooler  121 , there remains sufficient temperature differential between the cooling air that is being drawn across both coolers  121  and  122  with fan  131 . Typically the LT cooler  121  rejects only about 5% or less of the heat transferred to the air in the combined LT and HT circuit, and therefore, the heat pick up by the air as it passes across the LT cooler  121  is typically on the order of about 1-2 deg. F. The HT circuit receives the hot coolant from the engine  150  via HT supply line  143  and then the HT cooler  122  cools the liquid coolant with the air that is drawn across the HT cooler  122  by fan  131 . The cooled HT coolant is returned to the engine  150  through the HT return line  144 . In an embodiment of the present invention, both the HT and LT coolers  121  and  122  are radiator style heat exchangers. 
         [0036]    The compressor intercooling water cooler  123  (CIC) provides critical coolant to the major systems of the intercooled compression system  159  including the intercoolers  154 , which cool the air between the stages of the compressor  153 , and lube oil cooler  179  which cools the oil that is used for lubrication of the compressor  153  as well as other possible oil systems. For example, other equipment requiring lubrication includes a gear box (not shown) between the engine  150  and the compressor  153 . Also, the lube oil system  179  is integrated in series with a compressor lube oil system, and as such, the lube oil cooling system  179  discussed herein would cool the lube oil for both the compressor  153  and the gear box (not shown). The CIC  123  receives the hot liquid coolant via supply line  145  from the compressor coolant discharge manifold  156  and passes it through the CIC  123 . Air is drawn across the CIC  123  by a CIC fan  132  and the fluid in the CIC  123  is cooled and returned via the compressor coolant return line  146  and return manifold  155 . The compressor coolant return manifold  155  supplies the cooled coolant to the lube oil cooler  179  and the intercooler  154 . One or more coolant throttling valves (not shown) can be used to adjust the amount of flow that goes to the lube oil cooler  179  and the intercoolers  154 . Similarly, and for maintenance purposes, one or more coolant isolation and drain valves (not shown) can be used to drain or isolate the lube oil cooler  179  and the intercoolers  154 . The hot lube oil is pumped to the lube oil cooler  179  where it is cooled with the coolant from the return line  146 . The lube oil is then returned to the compressor  153  via return line  157  where it is heated from operation of the compressor  153 . The lube oil system may also contain a mechanical pump driven by the air compressor and an electric backup lube oil pump to circulate the lube oil through the system (both pumps not shown). 
         [0037]    Through the arrangement discussed above, the three coolers  121 ,  122 , and  123 , can also be sized and laid out as shown in  FIG. 5 , where the intercooled compressor system  159  has a footprint, as shown in a top elevation view in  FIG. 5 , such that multiple systems can be arranged next to each other in a modular fashion. The modularity of the air compression systems has many benefits including that each system is capable of being operated and cooled independently such that if there were multiple air compression systems at a site and there was a problem with the cooling system, not all the air compression systems would be affected. Also, because the compressed air generating system is modular, they can be moved easily without affecting the balance of plant equipment. The cooling system  501  has a total width  504  based on the width of the intercooled compressor system  159  and a left overhang  502  and a right overhang  503 . The total width  504  of the system dictates the minimum spacing  505  between the intercooled compressor systems  159 . This spacing is a critical parameter in gas turbine power plants which are often space constrained. For example, in environments where space is at a premium, cooling air systems may need to be stacked on top of each other, where the first floor of the cooling air system is on a cement foundation and a second floor of cooling air systems are on a steel structure. In this case, the HT and LT coolers and the compressor intercooler water cooler are arranged above the cooling air systems and can be arranged in a number of layouts to retain the modularity of the system. Alternately, if a permanent system is desired and the modularity is not required, one LT, HT and intercooler circuit could be used to cool all of the fuel-driven air compression systems. 
         [0038]    Referring now to  FIG. 2 , an alternate layout for the compressed air generating system is shown, where the compressor intercooling cooler  223  is increased in size compared to that of the embodiment in  FIG. 1 . This configuration may be required where minimal spacing between air compression systems exists or in cases of high ambient air temperatures where the compressor intercooling cooler  223  has to be increased in size. As shown in  FIG. 2 , the larger compressor intercooling cooler  223  is arranged such that the cooling air being drawn by fan  131  across the LT cooler  121  and HT cooler  122  circuit (for cooling the engine  150 ) provides additional cooling to the compressor intercooling cooler  223 . Alternately (not shown), depending on the expected LT cooler load and coolant temperature, the compressor intercooling cooler  223  could be arranged such that the cooling air being drawn by fan  131  across the LT  121  and HT  122  circuits first provides cooling to the LT cooler  121  and then cooling to the compressor intercooling cooler  223 . 
         [0039]    Referring now to  FIG. 3 , independent of the physical arrangement discussed above, it may be necessary or desirable to further cool the lube oil system for the compressor  153 .  FIG. 3  shows an additional lube oil cooler  378  that can be driven by a source of electrical or mechanical power  377  from the engine or compressor drive train. Here, the additional lube oil cooler  378  adds additional cooling to the cooling fluid from supply line  146  being supplied from the air cooler or directly to the oil itself (not shown). 
         [0040]    Alternately, and as shown in  FIG. 4 , the lube oil cooler  179  can be cooled with a separate cooling system  478  driven by a source of electrical or mechanical power  477  from the engine or compressor train. 
         [0041]    Referring now to  FIG. 6 , an alternate embodiment of the present invention is disclosed in which CIC  123  and LT cooler  121  from the jacket of engine  150  are combined in series and positioned adjacent the HT cooler  122 . Hot coolant from the engine jacket combines with coolant from the intercooler  154  and lube oil system  179  in a supply line  145 . This coolant passes through the coolers  121  and  123  before it is returned to the engine jacket via return line  141  and to the intercooled compressor and lube system via return line  146 . 
         [0042]    A slightly different physical arrangement of the present invention is depicted in  FIG. 7 . In this embodiment of the present invention, an air cooling system  420  comprises a LT cooler  421 , an HT cooler  122 , and a compressor intercooling cooler  423 , where the LT cooler  421  and compressor intercooling cooler  423  are in series. The HT cooler  122  is positioned vertically above the other coolers in air cooling system  420 , similar to that of the embodiment in  FIG. 1 . 
         [0043]    Referring now to  FIG. 8 , an alternate embodiment of the present invention is depicted. In this embodiment of the present invention, the three coolers  521 ,  522 , and  523  used for cooling coolant for the jacket of the engine  150  and the intercooled compressor  151  are located adjacent to each other and above the air compression system  159 . In the configuration shown in  FIG. 8 , each of the coolers  521 ,  522 , and  523  operate in parallel with their respective supply and return lines for coolant flow. 
         [0044]    Referring now to  FIG. 9 , an alternate embodiment of the present invention is disclosed. In this embodiment of the present invention, the CIC and HT engine coolers,  923  and  921  respectively, are depicted where the HT engine cooler  921  is used for cooling the coolant for the jacket of the engine  150 . The two coolers, HT engine  921  and CIC  923  are located adjacent to each other and vertically above the intercooled compression system  159  with the LT cooler  922  utilizing compartment vent air  931 , either on the inlet side of the intercooled compression system  159  or the exhaust side of the compartment to cool the LT engine cooling circuit. In the configuration shown in  FIG. 9 , each of the coolers  921 ,  922 , and  923  operate in parallel and independent with their respective supply and return lines for coolant flow. One element of this particular cooling configuration is that when the LT cooler  922  is implemented as shown, this configuration can be used independent of HT cooler  921  and the compressor intercooler  923 . This is significant because it allows commonality between the coolers. For example, if the circuits for HT cooler and compressor intercooler were utilizing plant water for coolant, then the LT cooler  922  could still be as shown in  FIG. 9 , which drives commonality and cost reduction in the packaging of the intercooled compression system  159 . 
         [0045]      FIG. 10  depicts a perspective view of an embodiment of the present invention. More specifically, an intercooled compressor system  159  is positioned in the lower portion of  FIG. 9 . The intercooled compressor system  159 , which includes an intercooled compressor driven by a fueled engine, is contained within the container depicted in  FIG. 9 . Positioned above the intercooled compressor system  159  is the air cooling system  120  comprising the LT cooler  121 , HT cooler  122 , compressor intercooling cooler  123 , and fans  131  and  132  which draw air across the coolers  121 ,  122 , and  123 . Also depicted in  FIG. 10  is the series of supply and return lines for the coolant flow passing between intercooled compressor system  159  and the air cooling system  120 , as indicated by the arrows in  FIG. 10 . 
         [0046]    Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention. Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense. 
         [0047]    From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure. 
         [0048]    It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of the claims.