Patent Publication Number: US-2015082791-A1

Title: Steam turbine system with steam turbine clutch

Description:
FIELD OF THE INVENTION 
     The disclosure relates generally to a steam turbine including a clutch for engaging or disengaging one or more high pressure sections from a power generator of the steam turbine, depending on a mode of operation. 
     BACKGROUND OF THE INVENTION 
     Many of today&#39;s steam turbines can be run in multiple modes of operation. For example, many turbines will run on high pressure steam during peak hours of operation and may switch to a low pressure steam during low energy generation. Typical steam turbines have a high pressure section and a low pressure section. However, when the turbine is run at a low pressure, the high pressure section is still utilized. In many cases, this results in a high pressure section being engineered to also accommodate low pressure steam, and thus low temperature steam. These configurations can alter the performance of the high pressure section, requiring changes in performance features as well as requiring moisture removal provisions within the high pressure section. 
     Further, the temperature changes associated with switching back and forth between a high pressure and high temperature steam to a low pressure and low temperature steam may cause thermal stress and thermal growth to components of the steam turbine. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Embodiments of the invention disclosed herein may include a steam turbine system comprising: a steam generator coupled to a high pressure section and a low pressure section; a first portion of a drive shaft coupled to the high pressure section; a clutching device for releasably coupling to a power generator coupled to the first portion of the drive shaft; and a second portion of the drive shaft for coupling to the power generator coupled to the low pressure section. 
     Embodiments of the invention may also include a method of operating a steam turbine system, the method comprising: delivering steam from a steam generator to at least one of a high pressure section and a low pressure section; engaging or disengaging, by a controller, a clutching device which is releasably coupled to a power generator via a first portion of a drive shaft from the high pressure section; and supplying power to the power generator via a second portion of the drive shaft which is coupled to the power generator from the low pressure section 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       These and other features of the disclosure will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various aspects of the invention. 
         FIG. 1  shows an illustrative steam turbine system in a conventional configuration according to the prior art. 
         FIG. 2  shows an illustrative steam turbine with a steam turbine clutch engaged according to some embodiments of the invention. 
         FIG. 3  shows an illustrative steam turbine with a steam turbine clutch disengaged according to some embodiments of the invention. 
         FIG. 4  shows an illustrative concentrated solar power system including the steam turbine system according to some embodiments of the invention. 
     
    
    
     It is noted that the drawings may not be to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings. The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Disclosed herein is a steam turbine system including a steam turbine clutching device for disengaging a high pressure section from a power generator during low energy supply operation. Turning to  FIG. 1 , in the prior art, a steam generator  110  would provide steam to a high pressure section  120  of steam turbine system  100 . The steam would expand within high pressure section  120  and exhaust from high pressure section  120  and would then pass to low pressure section  130 . In low pressure section  130 , the steam would again expand, exhausting to the condenser  140 . During this operation, a first portion of a drive shaft  150  from high pressure section  120  and a second portion of the drive shaft  155  from low pressure section  130  would always provide shaft power to a power generator  160 . 
     Still referring to  FIG. 1 , with both the first and second portions of the drive shafts  150  and  155  constantly supplying shaft power to power generator  160 , high pressure section  120  and low pressure section  130  are both engineered to work with both high energy steam and low energy steam. However, these sections cannot be optimized for both operating condition. 
     Turning to  FIG. 2 , according to one embodiment, disclosed is a steam turbine system  200  for power generation with a steam turbine clutching mechanism. In one embodiment, steam turbine system  200  includes, similar to the prior art, a steam generator  210 . Steam generator  210  is still coupled to a high pressure section  220 , however steam generator  210  is also coupled to a low pressure section  230  via a system of pipes which may include valves, which will be described with more detail below. While a steam turbine system  200  is demonstrated in  FIG. 2  with only two sections, embodiments of the disclosure can be utilized with any multiple numbers of coupled sections. According to some embodiments, a condenser  240  is coupled to low pressure section  230 . Any known condenser for a steam turbine may be utilized. Unlike the prior art, high pressure section  220  is coupled to a first portion of a drive shaft  250 , which is also coupled to a steam turbine clutch, or a clutching device  270 , which is releasably coupled to a power generator  260 . Clutching device  270  may include any known clutch. However, by example, clutching device  270  may include a single or multiple plate dry clutch, a wet clutch, or any planetary clutch. 
     Further regarding  FIG. 2 , low pressure section  230  is coupled to a second portion of the drive shaft  255  which is coupled to power generator  260  also. Releasably coupled indicates that clutching device  270  may be engaged in one position, or disengaged in a second position, from power generator  260 , both while still being coupled to power generator  260 , the function of which is further described below. While embodiments of the invention are described including a single drive shaft with two portions  250  and  255 , with clutching device  270  releasably coupled between first portion of the drive shaft  250  and power generator  260 , thus second portion of drive shaft  255  between clutching device  270  and coupled to low pressure section  230  and power generator  260 , this is only illustrative. It should be understood that instead of portions of the drive shaft  250  and  255 , two separate drive shafts may be utilized, or more if more than high pressure section  220  and low pressure section  230  are utilized. 
     Still referring to  FIG. 2 , clutching device  270  allows for steam turbine system  200  to be efficiently utilized for different modes of operations. For instance, when clutching device  220  is engaged, first portion of the drive shaft  250  supplies shaft power from high pressure section  220  to power generator  260 . However, when clutching device  270  is disengaged, first portion of the drive shaft  250  does not supply power from high pressure section  220  to power generator  260 . However, in both instances, second portion of the drive shaft  255  can provide shaft power to power generator  260  from low pressure section  230 . 
     Clutching device  270  can be useful in a number of embodiments. For instance, clutching device  270  may be engaged during a period of higher energy output from steam turbine system  200 , referred to as a high energy operating condition. A high energy operating condition can consist of a period of high pressure steam, high temperature steam, or a combination thereof. High energy operating conditions may include temperature ranges of approximately 370° C. to approximately 600° C. and a pressure range of approximately 6,895 kPa (1000 PSI) to approximately 20,684 kPa (3000 PSI), or approximately 6,895 kPa (1000 PSI) to approximately 13,790 kPa (2000 PSI). Further, clutching device  270  may be disengaged during a period of lower energy output from steam turbine system  200 , referred to as a low energy operating condition. It should be understood that a low energy operating condition may include a period of low pressure steam, low temperature steam, or some combination thereof. Low energy operating conditions may include temperature ranges of approximately 100° C. to approximately 300° C. and a pressure range of approximately 414 kPa (60 PSI) to approximately 5,516 kPa (800 PSI), or approximately 689 kPa (100 PSI) to approximately 2,413 kPa (350 PSI). 
     By integrating clutching device  270  into steam turbine system  200 , both high pressure section  220  and low pressure section  230  can be optimized for the proper operating conditions of each instance. For instance, since high pressure section  220 , in some embodiments, may not be exposed to any low energy steam, advanced performance features may be integrated into this section and moisture removal systems may not need to be installed. This can provide a boost in the energy conversion efficiency of high pressure section  220 . Further, low pressure section  230  can be further optimized for the handling of low energy steam. Another feature of the current disclosure is that rapid temperature changes that may occur during changes between high energy and low energy conditions can be obviated in high pressure section  220  by moving low energy steam directly to low pressure section  230 , which will usually already exist at comparable temperatures to the low energy steam. 
     Still referring to  FIG. 2 , steam turbine system  200  may further include a system of valves to assist in the operation of clutching device  270 . For instance, steam turbine system  200  may include a high pressure throttle valve  280  located between steam generator  210  and high pressure section  220 , a high pressure bypass valve  285  located between steam generator  210  and low pressure section  230 , and a low pressure throttle valve  290  between high pressure section  220  and low pressure section  230 . When used in conjunction with clutching device  270 , the system of valves can further aid in the redirection of steam during different operating conditions. 
     For instance, as illustrated in  FIG. 2 , high pressure throttle valve  280  and low pressure throttle valve  290  are both open, as indicated by the darkened valves, while clutching device  270  is engaged. High pressure bypass valve  285  is accordingly closed, as indicated by the white valve, so as not to bypass high pressure section  220 . In this embodiment, steam will be allowed to flow from steam generator  210  to high pressure section  220  and then to low pressure section  230 . This, as described above, can be useful during a high energy operating condition. Turning to  FIG. 3 , high pressure throttle valve  280  and low pressure throttle valve  290  are both closed while clutching device  270  is disengaged. High pressure bypass valve  285 , on the other hand is open so as to bypass high pressure section  220 . In this embodiment, steam can bypass high pressure section  230  from steam generator  210  and proceed directly to low pressure section  230 . This, as described above, can be useful during a low energy operating condition to reduce strain on or damage to high pressure section  220 . 
     As described above, in embodiments utilizing a system of valves, when clutching device  270  is engaged, first portion of the drive shaft  250  supplies power from high pressure section  220  to power generator  260 . When clutching device  270  is disengaged, instead first portion of the drive shaft  250  does not supply power from high pressure section  220  to power generator  260 . However, in both instances, second portion of the drive shaft  255  can provide shaft power to power generator  260  from low pressure section  230 . Although described as a system of three valves, it should be understood that there may be more valves, especially in embodiments including more than the two disclosed sections, high pressure section  220  and low pressure section  230 . 
     In a further embodiment, a method of operating steam turbine system  200  is disclosed. For instance, as shown in  FIGS. 2 and 3 , steam turbine system  200  may include a controller  295  coupled to steam turbine system  200 . Controller  295  may be connected directly to steam generator  210 , as illustrated. However, it should also be understood that controller  295  may be connected to any portion of steam turbine system  200 , including being hardwired directly into the system logic, which is not illustrated. In any case, the method can be implemented using controller  295 . Controller  295  may be automated, wherein it is capable of detecting an operating condition of steam turbine system  200  and adjusting accordingly. Controller  295  may also be programmable, such that it is programmed to run steam turbine system  200  at certain conditions based on many factors, such as time of day, current season, month, or year, average temperatures, or any other variables that may affect operating conditions of steam turbine system  200 . 
     In any case, the method may include delivering steam from steam generator  210 . Any known type of steam turbine system  200  with a steam generator  210  may be used. The steam is then sent to at least one of high pressure section  220  and low pressure section  230 . The steam can be sent to sections  220  and  230  via any known mechanism, including but not limited to pipes typically fitted within steam turbine system  200 . The steam expands through low pressure section  230  alone, or also through high pressure section  220 . The method may also include engaging or disengaging, by controller  295 , clutching device  270 , which is releasably coupled to power generator  260  via first portion of the drive shaft  250  from high pressure section  220 , as described above. Power is supplied to power generator  260  via second portion of the drive shaft  255 , which is coupled to power generator  260  from low pressure section  230 . The method may also include exhausting the steam to condenser  240 , which may be coupled to low pressure section  230 . 
     In the disclosed method, when clutching device  270  is engaged, as illustrated in  FIG. 2 , the method can include supplying shaft power from high pressure section  220  to power generator  260  via first portion of the drive shaft  250 , as the steam can pass through both high pressure section  220  and low pressure section  230 . Further, when clutching device  270  is disengaged, as illustrated in  FIG. 3 , first portion of the drive shaft  250  does not supply power from high pressure section  220  to power generator  260 . 
     The method may further include utilizing high pressure throttle valve  280  between steam generator  210  and high pressure section  220 , utilizing high pressure bypass valve  285  between steam generator  210  and low pressure section  230 , and utilizing low pressure throttle valve  290  between high pressure section  220  and low pressure section  230 . In such an embodiment, when clutching device  270  is engaged by controller  295 , first portion of the drive shaft  250  supplies power from high pressure section  220  to power generator  260 , and when clutching device  270  is disengaged by controller  295 , first portion of the drive shaft  250  does not supply power from high pressure section  220  to power generator  260 . However, whether clutching device  270  is engaged or disengaged, second portion of the drive shaft  255  supplies power from low pressure section  230  to power generator  260 . 
     With further reference to these embodiments of the disclosed method, when clutching device  270  is engaged by controller  295 , as shown in  FIG. 2 , high pressure throttle valve  280  and low pressure throttle valve  290  are opened by controller  295  to allow steam to pass through, and high pressure bypass valve  285  is closed by controller  295 . However, when clutching device  270  is disengaged by controller  295 , as shown in  FIG. 3 , high pressure throttle valve  280  and low pressure throttle valve  290  are closed by controller  295  so as to block steam from passing through high pressure section  220 , and high pressure bypass valve  285  is opened by controller  295  to allow steam to pass through only low pressure section  230 . 
     As further detailed above, in embodiments of the method, clutching device  270  may be engaged during a high energy operating condition, while clutching device  270  may be disengaged during a low energy operating condition. 
     Embodiments of this method may be beneficial to many steam turbine systems. As one example, this method may be beneficial in a concentrated solar power system, where clutching device  270  may be engaged during a daytime operating condition or clutching device  270  may be disengaged during a nighttime operating condition. 
     For example, in one embodiment, steam turbine system  200  is used in a concentrated solar power (CSP) system  300 , as illustrated in  FIG. 4 . The CSP system  300  may include any type of concentrated solar power system (CSPS), such as a CSP steam turbine (CSPST) or CSP evaporator (CSPE)  300  which can include a plurality of solar receptors  310  of any known configuration. The solar receptors  310  can include, for example, reflecting and or absorbing solar surfaces such as mirrors, prisms, photovoltaic panels, or semi-transparent surfaces for either absorbing or redirecting solar energy from a solar energy source, such as the sun, in order to generate steam for powering steam turbine system  200 , shown included in CSP system  300 . In the case that the CSP system  300  includes a CSPST, it is understood that the CSPST can take the form of any conventional concentrated solar power steam turbine, in that it may include one or more parabolic troughs, focused boilers, or other components found in such CSPST systems. The depiction of the CSP system  300  herein is merely illustrative of one form of concentrated solar power steam turbine capable of interacting with the control systems and/or computer systems described according to the various embodiments of the invention. 
     Still referring to  FIG. 4 , CSP system  300 , which is illustrative of a typical CSP system but may include any other CSP systems now known or later developed, can experience high energy operating conditions and low energy operating conditions. For instance, typically a daytime operating condition will consist of a higher energy operating condition due to the prevalence of sunlight. Such high energy operating conditions may include, for example, approximately 900° C. and approximately 6,205 kPa (1500 PSI). During this time, clutching device  270  will be engaged ( FIG. 2 ) to allow for processing of a higher energy steam through both high pressure section  220  and low pressure section  230 . However, a nighttime operating condition can often result in a lower energy operating condition due to the lack of sunlight, at which point clutching device  270  may be disengaged ( FIG. 3 ) to more efficiently process the lower energy steam directly through low pressure section  230 , bypassing high pressure section  220 . Nighttime operating conditions may include approximately 400° C. and approximately 1724 kPa (250 PSI). It should be understood that not all daytime operating conditions may be high energy operating conditions. For instance, on cloudy or overcast days, it may be optimal to run at low energy nighttime operating conditions. 
     It should be understood that while the invention has been described as utilizing only one high pressure section  220 , one low pressure section  230 , one condenser  240 , one clutching device  270 , and three valves, more of each of these elements may be utilized in steam turbine system  200 . For instance, multiple low pressure sections  230  may be utilized, or a plurality of high pressure sections  220 , each of which may be releasably coupled individually. Further, any steam turbine system  200  with multiple sections now known or later developed may benefit from features of the invention, especially in the case of multiple operating conditions, be they based on energy, pressure, temperature, or any combination thereof. Each section may be optimized to run at particular conditions based on the turbine configuration and steam output. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.