US 20140205048A1 (19) United States (12) Patent Application Publication (10) Pub. N0.: US 2014/0205048 A1 Petzen et al. (54) (43) Pub. Date: SYSTEMS AND METHODS FOR PROVIDING (52) OVERRIDE CONTROL FOR A FEEDWATER US. Cl. CPC ...................................... .. G21C 7/36 (2013.01) PUMP RECIRCULATION VALVE USPC ........................................................ .. 376/210 57 (71) Applicant: GENERAL ELECTRIC COMPANY, (72) Inventors, John Petzen Salem VA (Us), Gautam Schenectady NY (Us) ’ J ’ . ( ABSTRACT ) . . . Systems and methods for prowdmg override control for a feedwater pump reelrculation valve are prOV1ded.Accord1ng ' Chatter.i Sc’henecte’ld NY (GS) processor may be con?gured to receive one or more measure ments associated With pump motor power driving feedwater _ ?CUTSRIC COMPANY’ C enec a y’ ( to one embodiment, a system may include a controller and a processor communicativer coupled to the controller. The y’ (73) ASSlgnee' Jul. 24, 2014 ) pump ?ow. The feedwater pump recirculation valve may be (21) _ Appl' NO" 13/747’986 con?gured to maintain a predetermined minimum recircula tion ?ow through the feedwater pump by regulating recircu lation pump ?ow through a recirculation line. The processor (22) _ Flled3 may be also con?gured to calculate, based at least in part on the one or more measurements, the recirculation pump ?ow, Jan- 23’ 2013 and compare the recirculation pump ?ow to the predeter mined minimum recirculation ?ow. Based at least in part on Publication Classi?cation the comparing, the processor may selectively provide an over nt. . 51ICl G21 C 7/36 'd l'glhfd r1 e contro s1 na tot e ee water (2006.01) um reelrcu atlon va ve pp'l'l to selectively modify the recirculation pump ?ow. 1 00 i Peedwater i 0 5 Pump 13o f......................... ? 1 :35 Dif'ferential» Pressure li‘iowmeter 1 25 Motor Control System 1 l5 Contro 1 ler ‘ 1 1‘3 Patent Application Publication Jul. 24, 2014 Sheet 1 0f 6 US 2014/0205048 A1 196 Feedwater Pump k”. “w 130 ? A 1 Diffbrcmial- ‘\ 110 1 $ 1 Prassul'e Ei’lnwmatar 1 Mom!" Cuntml Sysiem V (Innimller @ HG. i V Patent Application Publication Jul. 24, 2014 Sheet 2 0f 6 US 2014/0205048 A1 200 295 A Receive One 61“ Mare Measuremsnts Assaciated with Pump Mcmr PQ'W?l' Driving Feedwater Pump 55‘ 10W 21 GA 7 Based at Least in Part on the ?ne or Mare Mcasurcmcntse Calculate the Rscircuiation Pump Flaw Compare the Rcairouiatievn Pump Flaw to a 215 A Predctennincd Minimum Recimulatimi Flaw Based at Least in Part on {he Comparing, Salestiveiy 229 A Provide an Ovsiride Cantmi Signal m this Feifdwatar Pump Recirculatian Valve Patent Application Publication Jul. 24, 2014 Sheet 3 0f 6 US 2014/0205048 A1 com W cm S,Q\DS\QUQ\ » m.wi mmPE:02 EumEE.U“53uEuEm QBE0295m5u0m Patent Application Publication Jul. 24, 2014 Sheet 4 0f 6 US 2014/0205048 A1 hag/M WSEQU 58§m$. a? @md a? Sw?vmw mow MS“\7Qi MEast“,ch w.wmm mw Emg?WQ Qm a? m? Ei Patent Application Publication Pawer Jul. 24, 2014 Sheet 5 0f 6 US 2014/0205048 A1 Patent Application Publication Jul. 24, 2014 Sheet 6 0f 6 Programmed Data Eagle 63 Q US 2014/0205048 A1 620 Mammy 616 Operating sygmm PTO'TSSW 646 036 ‘5‘ ,\ l \ / Data Bus \ 660 I \ I{v} T“ ‘ I t" : =. L 5“ {1?me C svweaas) m (a IQ 600 // V V A l/O intertace?) v, 686 Jul. 24, 2014 US 2014/0205048 A1 SYSTEMS AND METHODS FOR PROVIDING OVERRIDE CONTROL FOR A FEEDWATER PUMP RECIRCULATION VALVE TECHNICAL FIELD [0001] This disclosure relates generally to feedwater pump control systems, and more particularly, to systems and meth ods for providing override control for a feedwater pump recir culation valve. BACKGROUND [0002] A feedwater pump can be used to supply feedwater into a steam boiler. To protect the feedwater pump from damaging conditions during operation, a ?ow through the The processor may also be con?gured to calculate, based at least in part on the one or more measurements, the recircula tion pump ?ow, and to compare the recirculation pump ?ow to the predetermined minimum recirculation ?ow. Based at least in part on the comparing, the processor may selectively provide an override control signal to the feedwater pump recirculation valve to selectively modify the recirculation pump ?ow. [0006] In one embodiment, another system may be pro vided. The system may include a feedwater pump, a control ler con?gured to control the feedwater pump, and a processor communicatively coupled to the controller. The processor may be con?gured to receive one or more measurements associated with pump motor power driving feedwater pump ?ow. The feedwater pump recirculation valve may be con?g feedwater pump is maintained above a recommended mini mum value. The recommended minimum value can be met by having a minimum ?ow recirculation valve recirculate water in the pump as needed. The minimum ?ow recirculation valve is conventionally controlled based on measurements of the feedwater pump delivery pressure or ?ow. ured to maintain a predetermined minimum recirculation [0003] in industrial applications is calculation of the ?uid ?ow rate differential-pressure ?owmeter, that recirculation pump ?ow is above the predetermined minimum recirculation ?ow based on readings of the pressure loss across a pipe restriction whereas the calculated recirculation pump ?ow based at least A conventionally used ?ow measurement technique ?ow through the feedwater pump by regulating recirculation pump ?ow through a recirculation line. The processor may also be con?gured to calculate, based at least in part on the one or more measurements, the recirculation pump ?ow, and to determine, based at least in part on a signal provided by a using a differential -pressure ?owmeter. Differential-pressure in part on the one or more measurements is below the prede ?owmeters can rely upon a pressure connection on both sides of a ?ow element, such as an ori?ce plate or venturi ?ow termined minimum recirculation ?ow. Based at least in part on the determining, the processor may provide an override control signal to the feedwater pump recirculation valve to increase the recirculation ?ow above the predetermined mini noZZle. The connections are called impulse lines, and typi cally contain root isolation valves at the piping connection to the main feedwater piping. If these impulse lines become partially or completely blocked by corrosion products or an incorrectly positioned root valve, the ?ow indication may be incorrect. If the ?ow indication reads higher than the actual mum recirculation ?ow. [0007] Other embodiments and aspects will become appar ent from the following description taken in conjunction with the following drawings. ?ow, the recirculation valve control loop may act based on the incorrect ?ow reading, causing the recirculation valve to close to a position that allows less ?ow through the pump than the recommended minimum, and pump damage can occur. BRIEF DESCRIPTION OF THE DISCLOSURE [0004] The present disclosure relates to systems and meth ods for providing override control for a feedwater pump recir culation valve. According to one embodiment, a method can be provided. The method can include receiving one or more measurements associated with pump motor power driving feedwater pump ?ow, wherein the feedwater pump recircu lation valve may be con?gured to maintain a predetermined minimum recirculation ?ow through the feedwater pump by regulating recirculation pump ?ow through a recirculation line, based at least in part on the one or more measurements, calculating the recirculation pump ?ow, and comparing the recirculation pump ?ow to the predetermined minimum recir culation ?ow. Based at least in part on the comparing, an override control signal to the feedwater pump recirculation valve may be provided to selectively modify the recirculation pump ?ow. [0005] According to one embodiment, a system may include a controller con?gured to control a feedwater pump and a processor communicatively coupled to the controller. BRIEF DESCRIPTION OF THE DRAWINGS [0008] FIG. 1 depicts a simpli?ed block diagram illustrat ing an example environment and a system in accordance with an embodiment of the disclosure. [0009] FIG. 2 depicts a process ?ow diagram illustrating an example method for providing override control for a feedwa ter pump recirculation valve, in accordance with an embodi ment of the disclosure. [0010] FIG. 3 depicts a process ?ow diagram illustrating a detailed example method for providing override control for a feedwater pump recirculation valve, in accordance with an embodiment of the disclosure. [0011] FIG. 4 depicts an example system for providing override control for a feedwater pump recirculation valve, in accordance with an embodiment of the disclosure. [0012] FIG. 5 depicts an example characteristic curve of power versus ?ow, in accordance with an embodiment of the disclosure. [0013] FIG. 6 depicts a block diagram illustrating a con troller for controlling a generator, in accordance with an embodiment of the disclosure. DETAILED DESCRIPTION The processor may be con?gured to receive one or more [0014] measurements associated with pump motor power driving feedwater pump ?ow. The feedwater pump recirculation valve may be con?gured to maintain a predetermined mini mum recirculation ?ow through the feedwater pump by regu lating recirculation pump ?ow through a recirculation line. ences to the accompanying drawings, which form part of the The following detailed description includes refer detailed description. The drawings include illustrations in accordance with example embodiments. These example embodiments, which are also referred to herein as “examples,” are described in enough detail to enable those Jul. 24, 2014 US 2014/0205048 A1 skilled in the art to practice the present subject matter. The example embodiments may be combined, other embodiments may be utilized, or structural, logical, and electrical changes may be made, without departing from the scope of the tion may be compared to a minimum pump ?ow per vendor speci?cations. If the ?ow is below the minimum ?ow set claimed subject matter. The following detailed description is, point, the loop controller for the feedwater pump recircula therefore, not to be taken in a limiting sense, and the scope is tion valve may receive an override control signal, and shifts from using the ?ow from the differential pres sure ?ow instru ment to using the ?ow calculated from pump power. [0020] The technical effects of certain embodiments of the disclosure may include preventing damage to a feedwater pump by detecting incorrect ?ow readings based on a redun de?ned by the appended claims and their equivalents. [0015] The embodiments described herein relate to systems and methods for providing override control for a feedwater pump recirculation valve. When the feedwater pump is in operation, the pressure of the ?uid passing through pump is increased. The temperature of the ?uid increased due to mechanical contact with the feedwater pump. If the ?ow rate of the ?uidpassing through the pump is too low the pump may overheat. To prevent or otherwise minimize overheating, many pumping systems use minimum recirculation piping to direct part or all of the pump discharge ?ow back upstream of the pump where the ?ow is cooled before returning to the pump. Some power plants include minimum ?ow recircula tion piping for feedwater pumps. The recirculation ?ow may be sent to the deaerator or condenser. During plant startup or shutdown, the demand for feedwater may be low. The control valve associated with the minimum ?ow recirculation piping may open to direct the ?ow back upstream. During normal operation, the demand for feedwater may be higher and the minimum ?ow recirculation valve is closed. The minimum ?ow recirculation valve may automatically protect feedwater pumps during low load operations. As the pump load drops istic curve of power versus ?ow, typically as supplied by the pump vendor. The ?ow calculated by the interpolation func dant backup minimum ?ow indication that is not susceptible to impulse line plugging failure modes. [0021] Referring now to FIG. 1, a block diagram illustrates a system environment 100 suitable for providing override control for a feedwater pump recirculation valve, in accor dance with one or more example embodiments. In particular, the system environment 100 may comprise a feedwater pump 105, a pump motor 110, a motor control system 115, a con troller 600, a differential-pressure ?owmeter 125, a current transformer 130, a potential transformer 135, and a feedwater pump recirculation valve 140. [0022] The feedwater pump 105 may be driven by the pump motor 110 to supply feedwater from a deaerator (not shown) to a boiler (not shown). The differential-pressure ?owmeter 125 may be con?gured to measure recirculation ?ow through the feedwater pump 105 and to provide a signal indicative of the measurements to the controller 600. The motor control below a predetermined minimum ?ow rate, the recirculation valve may cause the bypass bush to open a bypass ?ow path. The pump minimum ?ow rate is thus reached and maintained. [0016] The minimum ?ow recirculation valve may be con con?gured to measure pump motor power and transmit the measurements to the controller 600. trolled by measuring ?uid ?ow rate through the feedwater pump motor power may be detected by one or more trans pump. Conventionally, differential-pressure type ?owmeters formers connected to the motor control system 115. The one have been widely used in ?ow measurement techniques. In general, differential-pressure ?owmeters may rely upon a a potential transformer 135, and so forth. The feedwater pump pressure connection on both sides of a ?ow element, such as an ori?ce plate or venturi ?ow nozzle. The connections can be called impulse lines, and typically contain root isolation valves at the piping connection to the main feedwater piping. [0017] However, during commissioning, signi?cant amounts of corrosion products may be produced in power plant piping. If the impulse lines become partially or com pletely blocked by corrosion products or an incorrectly posi tioned root valve, the ?ow indication may be incorrect. If the ?ow indication reads higher than actual ?ow, a recirculation valve control loop may act based on the incorrect ?ow reading causing the recirculation valve to close to a position that allows less ?ow through the pump than the minimum required to prevent or otherwise minimize pump damage. [0018] In accordance with an embodiment of the disclo sure, pump motor power may be used to calculate actual developed ?ow through the feedwater pump to provide an override control signal to the feedwater pump recirculation valve if the pump power consumed indicates that ?ow through the feedwater pump is below a design minimum ?ow. [0019] Actual pump motor power may be detected by a smart motor control center (e.g., a GE Multilin MM300) and transmitted to a control system. Alternatively, pump current and voltage may be detected by current and potential trans formers directly connected to control system I/O cards and system 115 may be coupled to the pump motor 110 and [0023] In accordance with one example embodiment, or more transformers may include a current transformer 130, recirculation valve 140 may be con?gured to regulate recir culation ?ow through the feedwater pump 105. [0024] The operations of the feedwater pump 105 may be managed by the controller 600. The controller 600 may inter act with the differential-pressure ?owmeter 125 to receive measurements associated with pressure drops, ?uid levels, ?ow rates and so forth. The controller 600 may also interact with the motor control system 115 to receive a feedback associated with power consumption in the pump motor 110. [0025] In accordance with one example embodiment, pump motor power may be measured by transformers con nected to the motor control system 115. For example, feed water pump current and voltage may be detected by current and potential transformers 130, 135 connected to the control ler input/output (I/O) cards and calculated by the controller 600. [0026] During pump operation, ?ow may be constantly measured by a differential-pressure ?owmeter 125 and cor responding signals sent to the controller 600. When it is determined that the ?ow rate drops below a predetermined minimum recirculation ?ow recommended by a pump manu facturer, an alarm signal may be sent to the controller 600 to prevent or otherwise minimize possible pump damage. How ever, there may be instances, when the differential-pressure ?owmeter 125 shows an incorrect ?ow reading due to an calculated in the control system. The pump motor power may impulse line plugging failure in feedwater piping. Therefore, be converted into ?ow by using an interpolation function in the control system preprogrammed with the pump character in order to assure the correct feedwater pump operation, an override control of the feedwater pump recirculation valve Jul. 24, 2014 US 2014/0205048 A1 140 based on electrical power measurements may be pro characteristic curve of power versus ?ow, typically as pro vided. In particular, if the measured power indicates that recirculation ?ow through the feedwater pump 105 is below a vided by the pump manufacturer. The interpolation function predetermined minimum recirculation ?ow, the controller 600 may send an override control signal to the feedwater pump recirculation valve 140, which causes the recirculation valve 140 to open and allow more ?ow to the feedwater pump 105. This, in turn, will increase pump motor power and raise the ?ow above the predetermined minimum ?ow. Thus, ?ow calculations based on the pump motor power may allow veri fying measurements reported by the differential-pressure ?owmeter 125. [0027] In accordance with one example embodiment, the controller 600 may be con?gured to manage the operation of the feedwater pump recirculation valve 140 by providing an override control signal to modify the recirculation ?ow. For example, the override control signal may cause the feedwater may include a cubic interpolation function. [0032] In operation 215, the recirculation pump ?ow may be compared to the predetermined minimum recirculation ?ow. The minimum recirculation ?ow may depend on the pump design and the safety requirements of the plant and may be speci?ed by a pump manufacturer. [0033] In operation 220, based at least in part on the com paring, an override control signal may be selectively provided to the feedwater pump recirculation valve to modify the recir culation pump ?ow. For example, if the calculated recircula tion ?ow is below the predetermined minimum recirculation ?ow, the override control signal may be provided to the loop controller of the feedwater pump recirculation valve to increase the recirculation ?ow above the predetermined mini mum recirculation ?ow. Such an increase may help to avoid pump recirculation valve 140 to increase or decrease the overheating and further damage of the feedwater pump. The recirculation ?ow through the feedwater pump 1 05. The feed water pump recirculation valve 140 may also include a loop override control signal may be used to override a signal pro vided by a differential-pressure ?owmeter associated with the feedwater pump recirculation valve. When the signal pro controller (not shown) that regulates the operation of the feedwater pump recirculation valve 140. [0028] An operator may interact with the controller 600 via a user interface device, such as a keyboard, a mouse, a control panel, or any other device capable of communicating data to and from the controller 600. [0029] FIG. 2 depicts a process ?ow diagram illustrating an example method 200, in accordance with an embodiment of the disclosure. The method 200 may be performed by pro vided by the differential-pressure ?owmeter indicates that the recirculation ?ow is above the predetermined minimum recir culation ?ow, whereas the recirculation ?ow is below the predetermined minimum recirculation ?ow based on the one or more measurements, the override control signal may be provided to the feedwater pump recirculation valve to increase the recirculation ?ow above the predetermined mini mum recirculation ?ow. cessing logic that comprises hardware (e.g., dedicated logic, [0034] programmable logic, and microcode), software (such as soft override control for a feedwater pump recirculation valve, in accordance with an embodiment of the disclosure. Pump motor power may be used to determine an actual ?ow through ware run on a general-purpose computer system or a dedi cated machine), or a combination of both. In one example FIG. 3 depicts an example method300 for providing embodiment, the processing logic may reside at the controller a feedwater pump. In operation 305, one or more measure 600, which may, in turn, reside in a user device or in a server. ments associated with pump motor power driving the feed water pump ?ow may be received by a controller. The pump motor power may be detected by a motor control system. In accordance with one example embodiment, the pump motor The controller 600 may comprise processing logic. It will be appreciated by one of ordinary skill in the art that instructions said to be executed by the controller 600 may, in fact, be retrieved and executed by one or more processors. The con power may be detected by one or more transformers con troller 600 may also include memory cards, servers, and/or nected to the motor control system. computer discs. Although the controller 600 may be con?g [0035] ured to perform one or more steps described herein, other may be used to calculate the actual recirculation pump ?ow through the feedwater pump. The calculation may be per control units may be utilized while still falling within the scope of various embodiments. [0030] As shown in FIG. 2, the method 200 may commence in operation 205 with receiving one or more measurements associated with pump motor power driving feedwater pump ?ow. The feedwater pump recirculation valve may be con?g ured to maintain a predetermined minimum recirculation ?ow through the feedwater pump by regulating recirculation pump ?ow through a recirculation line. The pump motor power may be detected by a motor control system. In accor dance with one example embodiment, the pump motor power may be detected by one or more transformers connected to the motor control system. For example, the one or more trans formers may include a current transformer or a potential In operation 310, the received pump motor power formed using an interpolation function. The ?ow calculated by the interpolation function may be then compared to a predetermined minimum recirculation ?ow in operation 315. If it is determined, in operation 320, that the calculated ?ow is above the predetermined minimum recirculation ?ow, in operation 325, it may be reported that the feedwater pump is operating under safe conditions. However, if it is determined that the calculated ?ow is below the predetermined minimum recirculation ?ow, the recirculation ?ow may be compared to a measured recirculation ?ow, as determined by a differential pressure ?owmeter, in operation 330, to check whether the calculated ?ow properly correlates to the ?ow as measured by the differential-pressure ?owmeter. transformer. [0036] The signal provided by the differential-pressure [0031] ?owmeter may indicate that the recirculation ?ow is above In operation 210, the recirculation pump ?ow may be calculated, based at least in part on the one or more mea surements of pump motor power. An interpolation function may be utilized to calculate the feedwater pump ?ow. The pump motor power may be correlated to the ?ow by using the interpolation function. The interpolation function may be stored in the memory of the controller preprogrammed with a the predetermined minimum recirculation ?ow, whereas the recirculation ?ow is below the predetermined minimum recir culation ?ow based on the one or more measurements asso ciated with the pump motor power. In this case, the recircu lation valve control loop may act based on the incorrect ?ow reading causing the recirculation valve to move to a position Jul. 24, 2014 US 2014/0205048 A1 that allows less ?ow through the pump than the predeter characteristic curve of power versus ?ow, typically as pro mined minimum recirculation ?ow required to prevent or vided by a pump manufacturer. As shown in FIG. 5, the interpolation function 500 may include a cubic interpolation otherwise minimize pump damage. [0037] Thus, upon detection of difference between the ?ow calculated based on the pump motor power and the ?ow measured by the differential-pressure ?owmeter, in operation 335, failure in the operation of the differential-pressure ?ow meter may be reported in operation 345. The controller may then provide, in operation 350, an override control signal to the feedwater recirculation valve to modify the recirculation ?ow, i.e. transition from using the ?ow measured by the differential-pressure ?owmeter to using the calculated ?ow. In particular, the override control signal may be con?gured to cause the recirculation valve to increase the recirculation ?ow above the predetermined minimum recirculation ?ow as to allow for improved operation of a plant. That is, the override control signal may be used to override a signal provided by the differential-pressure ?owmeter associated with the feed water pump recirculation valve. [0038] If, on the other hand, the ?ow calculated based on the pump motor power corresponds to the ?ow measured by the differential-pres sure ?owmeter, and both ?ows are below the predetermined minimum recirculation ?ow, correct operation of the differential-pressure ?owmeter may be reported, in operation 340. In this case, the controller may provide a control signal to the feedwater pump recirculation to modify the recirculation pump ?ow. [0039] FIG. 4 depicts an example system 400 for providing override control for a feedwater pump recirculation valve, in accordance with an embodiment of the disclosure. Feedwater may be supplied by a deaerator 405 to a feedwater pump 410. The feedwater pump 410 may include a motor driven by a pump motor 415. The feedwater pump 410 may provide function, wherein the power is cubically proportional to the ?ow. [0042] FIG. 6 depicts a controller 600 for providing over ride control for a feedwater pump recirculation valve, in accordance with an embodiment of the disclosure. More spe ci?cally, components of the controller 600 may be used to receive one or more measurements associated with pump motor power driving a feedwater pump ?ow, wherein the feedwater pump recirculation valve may be con?gured to maintain a predetermined minimum recirculation ?ow through the feedwater pump by regulating recirculation pump ?ow through a recirculation line, calculate, based at least in part on the one or more measurements, the recirculation pump ?ow, compare the recirculation pump ?ow to a predetermined minimum recirculation ?ow, and based at least in part on the comparing, selectively provide an override control signal to the feedwater pump recirculation valve to selectively modify the recirculation ?ow. The controller 600 may include a memory 610 for storing programmed logic 620 (e.g., soft ware) and other data, such as, for example, measurements of pump motor power, recirculation ?ow, operational data asso ciated with parameters of a feedwater pump, a status of a feedwater pump recirculation valve, and the like. The memory 610 may also include an operating system 640. A processor 650 may utilize the operating system 640 to execute the programmed logic 620, and in doing so, the operating feedwater to high-pressure (HP) feedwater heaters and boil system 640 may also utilize the data 630. A data bus 660 may provide communication between the memory 610 and the processor 650. Users may interface with the controller 600 ers 435. The feedwater pump 410 may be equipped with a via at least one user interface device 670 such as a keyboard, feedwater pump recirculation valve 430, which recirculates mouse, control panel, or any other devices capable of com municating data to and from the controller 600. The controller 600 may be in communication with the feedwater pump recir water back to a condensate inlet of the deaerator 405. The feedwater pump 410 may be controlled and monitored by a controller 600. The controller 600 may regulate recirculation ?ow through the feedwater pump 410 to the HP feedwater heaters and boilers 435. [0040] A motor control system 440 coupled to the control ler 600 may periodically take measurements of pump motor culation valve online while operating, as well as in commu nication with the feedwater pump recirculation valve of?ine while not operating, via an I/O Interface 680. More speci? cally, one or more of the controllers 600 may carry out meth ods described with reference to FIGS. 2-3 including receiving power consumed during pump operation and provide the one or more measurements associated with pump motor measurements to the controller 600. Based on the measured power driving a feedwater pump, wherein the feedwater pump recirculation valve may be con?gured to maintain a pump motor power, the actual ?ow developed by the feedwa ter pump 410 may be calculated and the calculated ?ow may be compared to a predetermined minimum recirculation ?ow value. The calculated ?ow may then be compared to a ?ow measured by a differential-pressure ?owmeter 425. Based at least in part on the comparison, the controller 600 may selec tively provide an override control signal to the feedwater pump recirculation valve 430 to modify the recirculation ?ow. [0041] FIG. 5 depicts an example characteristic curve of power versus ?ow, in accordance with an embodiment of the disclosure. According to the embodiment, the power-?ow characteristic curve 505 represents the actual ?ow through a feedwater pump based on pump motor power measured by a motor control system. The calculation of the ?ow may be based on an interpolation function 500. The interpolation function 500 may comprise the pump motor power versus the recirculation ?ow. The interpolation function 500 may be stored in the memory of the controller preprogrammed with a predetermined minimum recirculation ?ow through a recir culation line; calculating, based at least in part on the one or more measurements, the recirculation pump ?ow, comparing the recirculation pump ?ow to the predetermined minimum recirculation ?ow, and based at least in part on the comparing, selectively provide an override control signal to the feedwater pump recirculation valve to selectively modify the recircula tion pump ?ow. Additionally, it should be appreciated by one reasonably skilled in the art that other external devices or feedwater pump recirculation valves may be in communica tion with the controller 600 via the I/O Interface 680. In the illustrated embodiment, the controller 600 may be located remotely with respect to the feedwater pump recirculation valve, although, it may be co-located or even integrated with the feedwater pump recirculation valve. Furthermore, the controller 600 and the programmed logic 620 implemented thereby may include software, hardware, ?rmware, or any combination thereof. It should also be appreciated that mul Jul. 24, 2014 US 2014/0205048 A1 tiple controllers 600 may be used and different features described herein may be executed on one or more different controllers 600. [0043] Accordingly, embodiments described herein may provide override control to the feedwater pump recirculation valve by measuring pump motor power. Based on the mea surements, the actual recirculation ?ow through the feedwa limited to the example embodiments described above. There fore, it is to be understood that the disclosure is not to be limited to the speci?c embodiments disclosed and that modi ?cations and other embodiments are intended to be included within the scope of the appended claims. Although speci?c may be set and irregularities in feedwater pump operations terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. What is claimed is: 1. A method for providing override control for a feedwater avoided or otherwise minimized. pump recirculation valve, the method comprising: ter pump may be calculated. Thus, a correct recirculation ?ow References are made to block diagrams of systems, receiving one or more measurements associated with pump methods, apparatuses, and computer program products motor power driving feedwater pump ?ow, wherein the feedwater pump recirculation valve is con?gured to maintain a predetermined minimum recirculation ?ow [0044] according to example embodiments. It will be understood that at least some of the blocks of the block diagrams, and com binations of blocks in the block diagrams, respectively, may be implemented at least partially by computer program instructions. These computer program instructions may be loaded onto a general purpose computer, special purpose computer, special purpose hardware-based computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute on the computer or other programmable data processing apparatus, create means for implementing the functionality of at least some of the blocks of the block diagrams, or combinations of through the feedwater pump by regulating recirculation pump ?ow through a recirculation line; based at least in part on the one or more measurements, calculating the recirculation pump ?ow; comparing the recirculation pump ?ow to the predeter mined minimum recirculation ?ow; and based at least in part on the comparing, selectively provid ing an override control signal to the feedwater pump recirculation valve to selectively modify the recircula tion pump ?ow. 2. The method of claim 1, wherein the override control blocks in the block diagrams discussed. [0045] These computer program instructions may also be signal is to override a signal provided by a differential-pres stored in a computer-readable memory that can direct a com sure ?owmeter associated with the feedwater pump recircu puter or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means that implement the function speci?ed in the block or blocks. The computer pro lation valve. 3. The method of claim 2, further comprising: determining that the signal provided by the differential gram instructions may also be loaded onto a computer or pressure ?owmeter indicates that the recirculation ?ow is above the predetermined minimum recirculation ?ow whereas the recirculation ?ow is below the predeter other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or mined minimum recirculation ?ow based on the one or more measurements; and other programmable apparatus to produce a computer imple mented process, such that the instructions that execute on the computer or other pro grammable apparatus provide steps for implementing the functions speci?ed in the block or blocks. [0046] One or more components of the systems and one or more elements of the methods described herein may be implemented through an application program running on an operating system of a computer. They also may be practiced with other computer system con?gurations, including hand held devices, multiprocessor systems, microprocessor based, or programmable consumer electronics, mini-computers, mainframe computers, etc. [0047] Application programs that are components of the systems and methods described herein may include routines, programs, components, data structures, and so forth that implement certain abstract data types and perform certain tasks or actions. In a distributed computing environment, the application program (in whole or in part) may be located in local memory, or in other storage. In addition, or in the alter based at least in part on the determining, providing an override control signal to the feedwater pump recircula tion valve to increase the recirculation ?ow above the predetermined minimum recirculation ?ow. 4. The method of claim 1, wherein the pump motor power is detected by a motor control system. 5. The method of claim 4, wherein the pump motor power is detected by one or more transformers connected to the motor control system. 6. The method of claim 1, wherein the calculating of the recirculation ?ow is based at least in part on an interpolation function. 7. The method of claim 6, wherein the interpolation func tion comprises the pump motor power versus the recirculation ?ow. 8. The method of claim 1, wherein the override control signal is provided to a loop controller of the feedwater pump recirculation valve. 9. The method of claim 1, further comprising comparing native, the application program (in whole or in part) may be the recirculation ?ow to a measured recirculation ?ow as located in remote memory or in storage to allow for circum determined by a differential-pressure ?owmeter. 10. The method of claim 9, wherein the override control stances where tasks are performed by remote processing devices linked through a communications network. [0048] Many modi?cations and other embodiments of the example descriptions set forth herein to which these descrip tions pertain will come to mind having the bene?t of the signal is con?gured to cause the recirculation valve to increase the recirculation ?ow. 11. A system for providing override control for a feedwater pump recirculation valve, the system comprising: teachings presented in the foregoing descriptions and the a controller con?gured to control a feedwater pump; and associated drawings. Thus, it will be appreciated the disclo a processor communicatively coupled to the controller and sure may be embodied in many forms and should not be con?gured to: Jul. 24, 2014 US 2014/0205048 A1 receive one or more measurements associated with pump 18. The system of claim 11, wherein the calculated recir motor power driving feedwater pump ?ow, wherein the feedwater pump recirculation valve is con?gured to maintain a predetermined minimum recirculation ?ow culation ?ow is compared to a measured recirculation ?ow through the feedwater pump by regulating recirculation signal is to cause the recirculation valve to increase the recir culation ?ow. 20. A system for providing override control for a feedwater pump ?ow through a recirculation line; based at least in part on the one or more measurements, calculate the recirculation pump ?ow; compare the recirculation pump ?ow to the predetermined minimum recirculation ?ow; and based at least in part on the comparing, selectively provide an override control signal to the feedwater pump recir culation valve to selectively modify the recirculation pump ?ow. 12. The system of claim 11, wherein the override control signal is to override a signal provided by a differential-pres sure ?owmeter associated with the feedwater pump recircu lation valve. 13. The system of claim 1 1, wherein the pump motor power is detected by a motor control system. 14. The system of claim 13, wherein the pump motor power is detected by one or more transformers connected to the motor control system. 15. The system of claim 11, wherein an interpolation func tion is utilized to calculate the feedwater pump ?ow. 16. The system of claim 15, wherein the interpolation function comprises the pump motor power versus the recir culation ?ow. 17. The system of claim 11, wherein the override control signal is provided to a loop controller of the feedwater pump recirculation valve. determined by a differential-pressure ?owmeter. 19. The system of claim 18, wherein the override control pump recirculation valve, the system comprising: a feedwater pump; a controller con?gured to control the feedwater pump; and a processor communicatively coupled to the controller and con?gured to: receive one or more measurements associated with pump motor power driving feedwater pump ?ow, wherein the feedwater pump recirculation valve is con?gured to maintain a predetermined minimum recirculation ?ow through the feedwater pump by regulating recirculation pump ?ow through a recirculation line; based at least in part on the one or more measurements, calculate the recirculation pump ?ow; determine, based at least in part on a signal provided by a differential-pressure ?owmeter, that recirculation pump ?ow is above the predetermined minimum recirculation ?ow whereas the recirculation pump ?ow based at least in part on the one or more mea surements is below the predetermined minimum recirculation ?ow; and based at least in part on the determining, provide an override control signal to the feedwater pump recir culation valve to increase the recirculation ?ow above the predetermined minimum recirculation ?ow. * * * * *