GB2601830A

GB2601830A - System and method for performance by steam generators or power plants

Info

Publication number: GB2601830A
Application number: GB2019715.8A
Authority: GB
Inventors: Ahlbrink Nils; Jagatsinh Virpura Ravindrasinh; Joshi Abhinaya; El Moursi Hossam; Ben-Hassain Aziz; Jan Wojciechowski Dariusz; Pantin Solacito Junover
Original assignee: General Electric Renovables Espana SL
Current assignee: General Electric Renovables Espana SL
Priority date: 2020-12-14
Filing date: 2020-12-14
Publication date: 2022-06-15
Anticipated expiration: 2040-12-14
Also published as: IL288869B2; GB2601830B; GB202019715D0; IL288869A; IL288869B1

Abstract

A system comprising a steam generation section 112 comprising steam generation components 218 configured to output steam, an auxiliary fluid source 206 and flow path arranged to convey auxiliary fluid to a heat transfer section 210 for providing heat to water flowing through the steam generation section, the heated water then heating said steam generating components. The system may include a superheater section 114 configured to receive steam from the steam generation components, the system arranged to convey auxiliary fluid to the superheater components 234 for heating thereof. Alternatively, the superheater section may be bypassed by the auxiliary fluid flow path. The system may be a solar power plant, the heating sections comprising solar heating panels. The auxiliary fluid may be steam, the source being a boiler, or direct or indirect storage means. The heat transfer section may comprise a first conduit with a second conduit wound around at least a part of the first conduit, and/or it may comprise a heat exchanger.

Description

SYSTEM AND METHOD FOR PERFORMANCE BY STEAM GENERATORS OR

POWER PLANTS

FIELD OF THE INVENTION

[000]] The present invention relates to power plants or steam generators or boilers, and, more particularly, startup and low load operation of power plants or steam generators or boilers, including, but not limited to, those which are subject to frequent shutdowns and startups.

BACKGROUND

[0002] Certain steam generators or boilers used in power plants are subject to frequent shutdown and startup. For example, concentrated solar power plants that have dependability on the solar energy to operate during daytime while shutting down in night (referred as shutdown period).

[0003] Such concentrated solar power plants use solar boilers for producing steam to operate steam turbines in turn producing electricity by utilizing generators. Generally, a solar boiler may include a steam generation or evaporator section and high temperature components, such as a superheater section or reheater. The steam generation section produces steam and supplies it to the high temperature components, such as the superheater section, which superheat the steam to supply superheated steam for operating the steam turbine. Each of the steam generation section or superheater section includes various fluidly connected panels having various fluid-carrying tubes arranged between respective top and bottom horizontal headers, which are thick-walled and generally insulated. These panels are heated by focusing sunrays thereon, in turn heating the fluid to be utilized for producing electricity.

[0004] During normal operation, the components of the solar power plant, such as the panels of the steam generation and superheater sections, reach relatively high temperatures, and, during the shutdown period, lose heat and reach relatively lower temperatures, which may be lower than those preferred or required for starting up the power plant, for example in the morning.

SUMMARY OF THE INVENTION

[0005] In a first aspect, there is provided a system comprising a steam generation section, a superheater section, an auxiliary fluid source, an auxiliary fluid flow path, and a heat transfer section. The steam generation section comprises one or more steam generation components configured to generate steam from water flowing through the steam generation section, and to output the generated steam to the superheater section. The superheater section comprises one or more superheater components configured to heat the steam received from the steam generation section. The auxiliary fluid flow path is configured to convey an auxiliary fluid from the auxiliary fluid source to the one or more superheater components, for heating the one or more superheater components. The auxiliary fluid flow path is further configured to convey the auxiliary fluid from the auxiliary fluid source to the heat transfer section. The heat transfer section is configured to provide for heat transfer between the auxiliary fluid received via the auxiliary fluid flow path and the water flowing through the steam generation section.

[0006] The auxiliary fluid may be a different fluid to the water flowing through the steam generation section, and in at least some aspect, is kept separate from the water flowing through the steam generation section [0007] The system may be a solar receiver of a solar power plant. The one or more steam generation components may comprise one or more steam generation panels. The one or more superheater components may comprise one or more superheater panels.

[0008] The auxiliary fluid may be steam. The auxiliary fluid source may be a fluid source selected from the group of sources consisting of a boiler, a direct storage means, or an indirect storage means.

[0009] The heat transfer section may comprise: a first conduit, the first conduit being a conduit of the steam generation section through which water flows; and a second conduit through which the auxiliary fluid flows. At least a part of the second conduit may be wound around at least part of the first conduit, or vice versa. The heat transfer section may comprise a heat exchanger. The heat transfer section may be configured to permit the auxiliary fluid to flow into a conduit that is arranged to carry the water within the steam generation section. The steam generation section may comprise a pump configured to pump water through the steam generation section. The heat transfer section may be configured to permit the auxiliary fluid to flow into the conduit that is arranged to carry the water within the steam generation section at a position downstream of the pump in a direction in which the water is pumped The system may further comprise means for removing water from the steam generation section responsive to the auxiliary fluid being introduced into the conduit that is arranged to carry the water within the steam generation section.

[0010] The auxiliary fluid flow path may be configured to convey an auxiliary fluid from the auxiliary fluid source to the one or more superheater components and then from the one or more superheater components to the heat transfer section.

[0011] The system may further comprise a bypass conduit arranged to permit a flow of the auxiliary fluid from the auxiliary fluid source to the heat transfer section which bypasses the one or more superheater components [0012] The system may further comprise a flash tank. The auxiliary fluid flow path may be configured to convey the auxiliary fluid from the heat transfer section to the flash tank [0013] The system may further comprise a drum, fluidly connected between the steam generation section and the superheater section, and a water source configured to supply liquid water to the drum. The drum may be arranged to output liquid water to the steam generation section, receive liquid water and/or steam from the steam generation section, and output the received steam to the superheater section.

[0014] In a further aspect, there is provided a method for performance by a system. The system comprises a steam generation section, an auxiliary fluid source, and a heat transfer section. The method comprises: outputting, by the auxiliary fluid source, an auxiliary fluid; causing the auxiliary fluid to flow from the auxiliary fluid source to the heat transfer section; transferring, by the heat transfer section, heat from the auxiliary fluid to water flowing through the steam generation section; and causing the heated water to flow through the heat transfer section, thereby to heat one or more steam generation components of the steam generation section.

[0015] The system may further comprise a superheater section The method may further comprise causing the auxiliary fluid to flow from the auxiliary fluid source to one or more superheater components of the superheater section, thereby to heat the one or more superheater components [0016] The system may be a solar power plant or a solar receiver of a solar power plant. The method may be performed at least during startup operation of the solar power plant [0017] In a further aspect, there is provided a method for performance by a system. The system comprising a steam generation section, a superheater section, an auxiliary fluid source, and a heat transfer section, wherein the steam generation section comprises one or more steam generation components configured to generate steam from water flowing through the steam generation section and to output the generated steam to the superheater section. The method comprises: outputting, by the auxiliary fluid source, an auxiliary fluid; causing the auxiliary fluid to flow from the auxiliary fluid source to the heat transfer section, the flow of the auxiliary fluid bypassing the superheater section; transferring, by the heat transfer section, heat from the auxiliary fluid to water flowing through the steam generation section, thereby to heat the water and to increase steam production by the one or more steam generation components of the steam generation section.

[0018] The system may be a solar power plant or a solar receiver of a solar power plant The method may be performed in low load operation of the solar power plant responsive to a detection of low solar light levels or low direct normal irradiance (DNI).

[0019] In a further aspect, there is provided a method of any of preceding aspect, wherein the system is the system of any preceding aspect.

[0020] These, together with the other aspects of the present disclosure and the various features of novelty that characterize the present disclosure, are pointed out with particularity in the present disclosure For a better understanding of the present disclosure, its operating advantages, and its uses, reference should be made to the accompanying drawings and descriptive matter in which there are illustrated exemplary embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The advantages and features of the present disclosure will be better understood with reference to the following detailed description and claims taken in conjunction with the accompanying drawings, wherein like elements are identified with like symbols, and in which: [0022] FIG. 1 is a schematic illustration (not to scale) showing an example of a solar power plant; [0023] FIG. 2 is a schematic illustration (not to scale) showing further details of the power plant, in accordance with an embodiment; [0024] FIG. 3 is a process flow chart showing certain steps of a startup process for the power plant; [0025] FIG. 4 is a process flow chart showing certain steps of a steam generation boosting process for the power plant; [0026] FIG. 5 is a schematic illustration (not to scale) showing details of a power plant, in accordance with a further embodiment; and [0027] FIG. 6 is a schematic illustration (not to scale) showing details of a power plant, in accordance with a yet further embodiment.

[0028] Like reference numerals refer to like parts throughout the description of several views of the drawings.

DETAILED DESCRIPTION

[0029] For a thorough understanding of the present disclosure, reference is to be made to the following detailed description, including the appended claims, in connection with the above-described drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one skilled in the art that the present disclosure can be practiced without these specific details. In other instances, structures and devices are shown in block diagrams form only, in order to avoid obscuring the disclosure. Reference in this specification to "one embodiment," "an embodiment," "another embodiment," "various embodiments," means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. The appearance of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.

Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments but may not be of other embodiments' requirement.

[0030] Although the following description contains many specifics for the purposes of illustration, anyone skilled in the art will appreciate that many variations and/or alterations to these details are within the scope of the present disclosure. Similarly, although many of the features of the present disclosure are described in terms of each other, or in conjunction with each other, one skilled in the art will appreciate that many of these features can be provided independently of other features. Accordingly, this description of the present disclosure is set forth without any loss of generality to, and without imposing limitations upon, the present disclosure. Further, the relative terms, such as "first," "second," "top," "bottom," and the like, herein do not denote any order, elevation or importance, but rather are used to distinguish one element from another. Further, the terms "a" and "an" herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

[003]] Referring now to FIG. 1, an example of a system 100 for at least one of startup and low load operation of a power plant having a fluid generating source, such as a solar operated power plant set-up 102 (tower plant 102') with a solar receiver, is illustrated in accordance with an embodiment of the present disclosure. However, where the system 100 is utilized with respect to other power plants other than the solar power plant, the solar receiver may be replaced by a steam generator or a boiler with or without (but usually with) superheating functionality. The system 100 for the power plant 102 includes a concentrated solar tower assembly 104 having a tower structure 106 and, as mentioned above, a solar receiver 108 placed on top thereof, where solar rays are concentrated from a heliostat 110 for production of electricity by utilizing a turbine (not shown in FIG. 1). In this embodiment, the solar receiver 108 includes a steam generation section (also referred to as an evaporator section) 112 and a superheater section 114 through which a working fluid flows for carrying the solar heat accumulated therein from concentrated solar rays received from the heliostat 110.

[0032] In as much as the construction and arrangement of the system 100 for the power plant 102 having the tower structure 106, the solar receiver 108 and the heliostat 110 are all well-known to those skilled in the art, it is not deemed necessary for purposes of acquiring an understanding of the present disclosure that there be recited herein all of the constructional details and explanation thereof Further, it should be understood that the tower structure 106 and the solar receiver 108 may include a variety of components for performing their respective purposes, and only those components are shown that are relevant for the description of various embodiments of the present disclosure.

[0033] FIG. 2 is a schematic illustration (not to scale) showing further details of the power plant 102, including the solar receiver 108, of this embodiment.

[0034] The solar receiver 108 comprises the steam generation section 112, the superheater section 114, a drum 200, a feedwater source 202, and a boiler circulation pump (hereinafter "BCP") 204. The solar receiver 108 is coupled to a feedwater source 202, an auxiliary boiler 206, a solar receiver blow down flash tank (hereinafter "BDFT") 208, as will be described in more detail later below. The solar receiver 108 further comprises a heat transfer section 210, a first valve 211, a second valve 212, a third valve 213, a fourth valve 214, a fifth valve 215, a sixth valve 216, and a seventh valve 217. In this embodiment, the solar receiver 108 further comprises first and second additional valves 251, 252.

[0035] The steam generation section 112 comprises a plurality of panels, hereinafter referred to as the "steam generation panels", 218 that are fluidly connected together. The steam generation panels 218 are configured to receive solar rays directed thereto by the heliostat 110, as indicated in FIG. 1 by dotted arrows and the reference numeral 220 to heat a fluid flowing therethrough.

[0036] A first fluid circulation path 221 is defined by one or more conduits that connect together, in a circuit or a loop, the steam generation panels 218, the first valve 211, the BCP 204, and the heat transfer section 210 [0037] A second fluid circulation path 222 is defined by one or more conduits that connect together, in a circuit or a loop, the steam generation panels 218, the drum 200, the second valve 212, the BCP 204, and the heat transfer section 210.

[0038] The BCP 204 is a pump configured to pump fluid around the first fluid circulation path 221 and the second fluid circulation path 221, as will be described in more detail later below with reference to FIGs 3 and 4 [0039] The first valve 211 is configured to control and/or regulate the flow of the fluid through or around the first fluid circulation path 221 The first valve 211 is

S

connected, on the first fluid circulation path 221, between the steam generation panels 218 and the BCP 204.

[0040] The second valve 212 is configured to control and/or regulate the flow of the fluid through or around the second fluid circulation path 222. The second valve 212 is connected, on the second fluid circulation path 222, between the drum 200 and the BCP 204.

[0041] The heat transfer section 210 is configured to transfer heat between fluids in various conduits. More specifically, in this embodiment the heat transfer section 210 comprises a first conduit 231 disposed between the BCP 204 and the steam generation panels 218, and a second conduit 232 that wraps or winds around the first conduit 231. The first conduit 231 is a conduit via which the BCP 204 may pump fluid to the steam generation panels 218, and forms part of both the first and second circulation paths 221, 222. The second conduit 232 is configured to convey steam from the superheater section 114 to the BDFT 208, as described in more detail later below.

[0042] The drum 200 is a container or vessel configured to store both liquid working fluid (i.e. water) and vapour (i.e. steam). The drum 200 fluidly connects the steam generation section 112 and the superheater section 114. The drum 200 is connected, on the second fluid circulation path 222, between the steam generation panels 218 and the second valve 212. The functionality of the drum 200 will be described in more detail later below with reference to FIGs. 3 and 4 [0043] In addition, the drum 200 is fluidly connected to the feedwater source 202, such that in operation the drum 200 may receive feedwater from the feedwater source 202.

[0044] The superheater section 114 comprises a plurality of panels, hereinafter referred to as "superheater panels", 234 that are fluidly connected together. The superheater panels 234 are configured to receive solar rays directed thereto by the heliostat 110, as indicated in FIG. 2 by dotted arrows and the reference numeral 236, to heat a fluid flowing therethrough.

[0045] The superheater panels 234 are fluidly connected to the drum 200 via the third valve 213. The third valve 213 is configured to control and/or regulate the flow of a fluid between the drum 200 and the superheater panels 234.

[0046] The superheater panels 234 are fluidly connected to the auxiliary boiler 206 via the fourth valve 214 such that steam generated by auxiliary boiler 206, hereinafter referred to as "auxiliary steam", may be received by the superheater panels 234, as will be described in more detail later below with reference to FIGs. 3 and 4. The auxiliary boiler 206 is a boiler configured to generate the auxiliary steam (e.g. from a water source, not shown in FIG. 2), and to provide that auxiliary steam to the superheater panels 234. The fourth valve 214 is configured to control and/or regulate the flow of a fluid (specifically, the auxiliary steam) from the auxiliary boiler 206 to the superheater panels 234.

[0047] The superheater panels 234 are further fluidly connected to the BDFT 208 via the fifth valve 215, the heat transfer section 210 and the first additional valve 251, such that the auxiliary steam, after having passed through the superheater panels 234, may be sent from or "dumped" by the superheater panels 234 into the BDFT 208, as will be described in more detail later below with reference to FIGs. 3 and 4. More specifically, the fifth valve 215 is fluidly connected between the superheater panels 234 and the second conduit 232 of the heat transfer section 210, and the second conduit 232 is fluidly connected between the fifth valve 215 and the BDFT 208. The fifth valve 215 is configured to control and/or regulate the flow of the auxiliary steam from the superheater panels 234, through the second conduit 232. The first additional valve 251 is located along the second conduit 232 between the heat transfer section 210 and the BDFT 208. The first additional valve 251 is configured to control and/or regulate the flow of the auxiliary steam from the superheater panels 234, through the heat transfer section 210 via the second conduit 232, and into the BDFT 208.

[0048] In this embodiment, the second additional valve 252 is located on a conduit that directly connects the superheater panels 234 to the BDFT 208, i.e. such that auxiliary steam can flow from the auxiliary boiler 206 into the BDFT 208, via the superheater panels 234 or conduit 240, directly into the BDFT 208. The second additional valve 252 is configured to control and/or regulate the flow of the auxiliary steam from the superheater panels 234 directly into the BDFT 208.

[0049] The BDFT 208 is a tank, vessel or container configured to receive, and safely store or dispose of, blown down fluid received from the superheater panels 234, as will be described in more detail later below with reference to FIGs. 3 and 4.

[0050] The superheater panels 234 are further fluidly connected to an outlet 238 of the solar receiver 108 via the sixth valve 216. The outlet 238 may be fluidly coupled to a turbine for producing electricity by utilizing superheated steam received from the superheater panels 234. The sixth valve 216 is configured to control and/or regulate the flow of superheated steam from the superheater panels 234 out of the outlet 238.

[0051] In this embodiment, the auxiliary boiler 206 is further fluidly connected to the second conduit 232 of the heat transfer section 210 via a so-called "bypass conduit" 240. The bypass conduit 240 fluidly connects the auxiliary boiler 206 to the second conduit 232 in a way that bypasses the superheater panels 234 such that auxiliary steam may be caused to flow from the auxiliary boiler 206 to the second conduit 232 without flowing through the superheater panels 234. The seventh valve 217 is disposed along the by-pass conduit 240 and is configured to control and/or regulate the flow of the auxiliary steam from the auxiliary boiler 206 to the second conduit 232 via the bypass conduit 240.

[0052] In operation, the power plant 102 will typically be subject to frequent startups and shutdowns. Specifically, during the daytime, the power plant 102 may nin in so-called "normal operation" mode in which the turbine drives the generator to generate electricity, while at nighttime it is shut down. During the shutdown period (i.e. overnight), components of the steam generation section 112 and the superheater section 114 (specifically the steam generation panels 218 and the superheater panels 234, and fluid therein) lose heat to ambient air, and tend to reach lower temperatures than those preferred or required for starting up the power plant 102 in the morning. A "startup" process is performed following a shutdown period to heat the components of the steam generation section 112 and the superheater section 114 to temperatures preferred or required for normal operation of the power plant 102 (i.e. electricity generation). Subsequent to the startup process being performed, the power plant 102 is run in normal operation mode, to produce electricity.

[0053] What will now be described with reference to FIG. 3 is an embodiment of a startup process that may be implemented by the power plant 102 to heat the components of the steam generation section 112 and the superheater section 114 to temperatures greater than or equal to those preferred or required for starting normal operation of the power plant 102.

[0054] FIG. 3 is a process flow chart showing certain steps of a startup process 300 for the power plant 102.

[0055] During the startup process 300, the first valve 211, the fourth valve 214, the fifth valve 215, and the first additional valve 251 are opened thereby to permit fluid flow therethrough. In contrast, the second valve 212, the third valve 213, the sixth valve 216, and the seventh valve 217 are closed thereby to prevent fluid flow therethrough.

[0056] At step s302, the auxiliary boiler 206 boils (and preferably superheats) water thereby to produce the auxiliary steam. In some embodiments, the auxiliary boiler 206 comprises superheating means such that the auxiliary steam is superheated. In some embodiments, a de-superheating station is implemented to reduce the temperature of the superheated auxiliary steam to a desired temperature.

[0057] At step s304, the auxiliary steam travels from the auxiliary boiler 206 to the superheater panels 234. The auxiliary steam output from the auxiliary boiler 206 may have a pressure of approximately 50bar, a temperature of approximately 350-515°C, and/or a flow rate of about 7-10kg/s.

[0058] The flow of the auxiliary steam from the auxiliary boiler 206 to the superheater panels 234 is permitted by the (open) fourth valve 214, and by the (open) fifth valve 215. At least one of the first additional valve 251 and the second additional valve 252 is open. In some embodiments, this flow of auxiliary steam may be controlled or regulated by the fourth valve 214, the fifth valve 215, the first additional valve 251, and/or the second additional valve 252 [0059] At step s306, the auxiliary steam travels through the superheater panels 234 thereby to heat the superheater panels 234 to a temperature greater than or equal to that preferred or required for starting up the power plant 102.

[0060] The superheater panels 234 may, additionally, be heated at least to some extent by incident solar rays 236, e.g. from the heliostat 110. However, due to initially low Sun angles and initially low direct normal irradiance (DNI), the heating effects of the solar rays may, at least initially, be relatively low.

[0061] At step s308, the auxiliary steam travels from the superheater panels 234 to the second conduit 232 of the heat transfer section 210.

[0062] The flow of the auxiliary steam from the superheater panels 234 to the second conduit 232 is permitted by the (open) fifth valve 215, and by the (open) first additional valve 251, and may, in some embodiments, be controlled or regulated by the fifth valve 215 and/or the first additional valve 251.

[0063] At step s310, the auxiliary steam travels through the second conduit 232 that is wrapped around the first conduit 231 within the heat transfer section 210. Due to the close proximity and intertwining of the first and second conduits 231, 232, heat energy is transferred from the relatively hot auxiliary steam travelling within the second conduit 232 to the relatively cooler fluid travelling within the first conduit 231 (which is typically water during startup of the power plant 102).

[0064] At step s312, the auxiliary steam travels through the second conduit 232 from the heat transfer section 210 and into the BDFT 208, where is it stored or disposed of The auxiliary steam dumped into the BDFT 208 may have a pressure of approximately 10-30bar, a temperature of approximately 180-300°C, and/or a flow rate of about 7-10kg/s upstream of the first additional valve 251.

[0065] Steps s302 to s312 of the startup process 300 may be performed continuously, thereby to provide a continuous flow of auxiliary steam from the auxiliary boiler 206 to the BDFT 208.

[0066] Steps s314 to s318 described below may be performed contemporaneously with the above-described steps s302 to s312.

[0067] At step s314, the BCP 204 pumps a fluid, which in this embodiment is water, within the first circulation path 221, from the BCP 204 to the steam generation panels 218 via the first conduit 231 of the heat transfer section 210. The water passing through the first conduit 231 is heated in the heat transfer section 210 by the relatively hot auxiliary steam flowing through the second conduit 232.

[0068] At step s316, the water pumped by the BCP 204 (which has been heated in the heat transfer section 210) travels through the steam generation panels 218 thereby to heat the steam generation panels 218.

[0069] The steam generation panels 218 may, additionally, be heated at least to some extent by incident solar rays 220, e.g. from the heliostat 110. However, due to initially low Sun angles and initially low DNI, the heating effects of the solar rays may, at least initially, be relatively low.

[0070] At step s318, the water pumped by the BCP 204 travels from the steam generation panels 218 back to the BCP 204 via the first valve 211 [0071] The flow of the water from the steam generation panels 218 back to the BCP 204 is permitted by the (open) first valve 211, and may, in some embodiments, be controlled or regulated by the first valve 211.

[0072] After step s318, the startup process 300 returns to step s314, whereby the water is recirculated about the first circulation path 221 by the BCP 204. Thus, the water within the first circulation path 221 is further heated by the heat transfer section 210 and the steam generation panels 218, thereby to heat to an increasingly higher temperature, and eventually to a temperature greater than or equal to that preferred or required for starting up the power plant 102.

[0073] The water/fluid within the first circulation path 221 may have a pressure within the range 1-30bar, and/or a temperature that increases over the course of the startup process within the range 50-230°C.

[0074] The startup process 300 may be performed at least until the steam generation panels 218 and the superheater panels 234 reach temperatures greater than or equal to those preferred or required for starting up the power plant 102, at which point the startup process 300 may end and transition to normal operation may begin, which may include closing of circulation path 221, stopping of auxiliary steam flow and opening of circulation path 222. In some embodiments, after the startup process 300 is performed, in which heated water is circulated around the first fluid circulation path 221, the first fluid circulation path 221 may be closed (e.g. by closing the first valve 211), and the second circulation path 222 may be opened (e.g. by opening the second valve 212). The auxiliary steam may continue to flow around the second circulation path 222 and may be further heated by the steam generation panels 218. The pressure and temperature of the fluid circulating in the steam generation section 112 may continue to rise until preferred or required process conditions are achieved. The process may then end, and normal operation may begin.

[0075] Thus, a process flow chart showing certain steps of a startup process for the power plant 102 is provided.

[0076] Advantageously, in the above-described startup process, the auxiliary steam used to heat up the superheater section 114, including the superheater panels 234, is additionally used to heat water within the steam generation section 112 [0077] Advantageously, the above-described startup process tends to reduce the time spent heating up the steam generation section 112, including the steam generation panels 218, e.g. in the morning following an overnight shut-down.

[0078] Advantageously, the above-described startup process tends to reduce the startup time of the power plant 102, e.g. in the morning following an overnight shut-down. Startup time for the power plant 102 may, for example, be reduced by 10-15minutes. Thus, the time the power plant spends in "normal operation" mode, i.e. producing electricity, tends to be increased.

[0079] In operation, the power plant 102 may experience period of relatively low light and/or low DNI. For example, during dawn and dusk, the angle of the Sun's incident rays to Earth's surface may be relatively shallow, leading to low DNI. Also, for example, periods during which the Sun is obscured by clouds may lead to a reduction in incident solar ray intensity. Such periods may be referred to as periods of low load operation. During and/or subsequent to such periods of low load operation (for example, periods of relatively low light and/or low DNI), steam generation by the steam generation section 112 may be reduced. This may lead to a reduced volume flow (or mass flow) of steam being received by the superheater section 114, and thus reduced electricity generation by the power plant 102. Thus, it may be desirable, during and/or subsequent to such periods of relatively low light and/or low DNI, to boost steam production by the steam generation section 112 so as to increase or maintain flow rates of steam being received by the superheater section 114.

[0080] What will now be described with reference to FIG. 4 is an embodiment of a so-called steam generation boosting process that may be implemented by the power plant 102 to increase a temperature of steam generated by the generation section 112, for example during periods of low DNI, etc. [0081] FIG. 4 is a process flow chart showing certain steps of a steam generation boosting process for the power plant 102.

[0082] During the steam generation boosting of FIG. 4, second valve 212, the third valve 213, the sixth valve 216, and the seventh valve 217 are open thereby to permit fluid flow therethrough. In contrast, the first valve 211, the fourth valve 214, and the fifth valve 215 are closed thereby to prevent fluid flow therethrough [0083] At step s402, the auxiliary boiler 206 boils (and, preferably, superheats) water thereby to produce the auxiliary steam [0084] At step s404, the auxiliary steam travels from the auxiliary boiler 206 to the second conduit 232 of the heat transfer section 210 via the bypass conduit 240 A portion of auxiliary steam may travel directly to the BDFT 208 via the second additional valve 252.

[0085] The flow of the auxiliary steam from the auxiliary boiler 206 to the second conduit 232 is permitted by the (open) seventh valve 217, and by the (open) first additional valve 251, and may, in some embodiments, be controlled or regulated by the seventh valve 217 and/or the first additional valve 251. A flow of the auxiliary steam through the superheater panels 234 is prevented by the closed fourth and fifth valves 214, 215.

[0086] At step s406, the auxiliary steam travels through the second conduit 232 that is wrapped around the first conduit 231 within the heat transfer section 210 Due to the close proximity and intertwining of the first and second conduits 231, 232, heat energy is transferred from the relatively hot auxiliary steam travelling within the second conduit 232 to the relatively cooler fluid travelling within the first conduit 231 (which typically comprises steam during normal operation of the power plant 102) [0087] At step s408, the auxiliary steam travels through the second conduit 232 from the heat transfer section 210 and into the BDFT 208, where is it stored or disposed of [0088] Steps s402 to s408 of the steam generation boosting process 400 may be performed continuously, thereby to provide a continuous flow of auxiliary steam from the auxiliary boiler 206 to the BDFT 208.

[0089] Steps s410 to s424 described below may be performed contemporaneously with the above-described steps s402 to s408.

[0090] At step s410, the drum 200 receives feedwater from the feedwater source 202. The feedwater may be received from the feedwater source 202 so as to keep a volume or level of feedwater within the drum (e.g. relative to a steam content level) at a predefined threshold level.

[009]] At step s412, the BCP 204 pumps a fluid, which may be liquid water (and may include a portion of the feedwater), within the second circulation path 222, from the drum 200 to the steam generation panels 218 via the first conduit 231 of the heat transfer section 210. The fluid passing through the first conduit 231 is heated in the heat transfer section 210 by the relatively hot auxiliary steam flowing through the second conduit 232. At least some of the fluid pumped through the first conduit 231 may be converted to steam.

[0092] The flow of the fluid from the drum 200 to the first conduit 231 is permitted by the (open) second valve 212, and may, in some embodiments, be controlled or regulated by the second valve 212.

[0093] At step s414, the fluid pumped by the BCP 204 (which may be a two-phase mixture of liquid water and steam downstream of the heat transfer section 210) travels through the steam generation panels 218, which further heat the fluid. The steam generation panels 218 heat the fluid travelling therethrough by means of solar rays 220, e.g. from the heliostat 110. This heating of the fluid by the steam generation panels 218 tends to convert a greater proportion of the fluid to steam.

[0094] At step s416, the two-phase mixture of liquid water and steam is pumped by the BCP 204 from the steam generation panels 218 back to the drum 200. The steam returning to the drum may have a pressure of about 30-190bar or higher.

[0095] At step s418, liquid water within the drum 200 is recirculated about the second circulation path 222 by the BCP 204. Thus, feedwater is continually converted to steam (i.e. steam is generated by the steam generation section 112) and returned to the drum 200 [0096] At step s420, steam within the drum 200 travels from the drum to the superheater panels 234 [0097] The flow of the steam from the drum 200 to the superheater panels 234 is permitted by the (open) third valve 213, and may, in some embodiments, be controlled or regulated by the third valve 213.

[0098] At step s422, the steam output from the drum 200 travels through the superheater panels 234 thereby to further heat (e.g. "superheat") the steam.

[0099] The superheater panels 234 heat the steam travelling therethrough by means of solar rays 236, e.g. from the heliostat 110.

[00100] At step s424, the superheated steam travels from the superheater panels 234 to the outlet 238, whereby the superheated steam exits the solar receiver. The superheated steam may then be used by a turbine of the power plant 102 for the production of electricity. The superheated steam output at the outlet 238 may have a temperature of approximately 400-570°C and/or a flow rate of about 15-135kg/s.

[00101] The flow of the steam from outlet 238 is permitted by the (open) sixth valve 216, and may, in some embodiments, be controlled or regulated by the sixth valve 216.

[00102] Steps s410 to s424 of the steam generation boosting process 400 may be performed continuously, thereby to provide a continuous flow of superheated steam from the outlet 238.

[00103] Thus, a process flow chart showing certain steps of a steam generation boosting process for the power plant 102 is provided.

[00104] In the above-described steam generation boosting process, the auxiliary steam from the auxiliary boiler 106 is advantageously used to provide additional heating to the fluid in the steam generation section 112 (i.e. in addition to that provided by the steam generation panels 218), thereby to increase the volume flow rate (or mass flow rate) and/or temperature of the steam provided by the steam generation section 112 to the superheater section 114.

[00105] Advantageously, the above-described steam generation boosting process tends to mitigate against periods of relatively low light and/or low DNI. The steam generation boosting process may be implemented to increase or maintain the volume flow rate (and/or mass flow rate) of steam supplied to the superheating section 114. The steam generation boosting process may be implemented to increase the volume flow rate (and/or mass flow rate) of steam supplied to the superheating section 114 above that which would otherwise be supplied if no steam generation boosting process was performed. The steam generation boosting process may be implemented to lengthen the time the power plant operates in normal operation, i.e. producing electricity.

[00106] In the above embodiments, the solar receiver comprises a heat transfer section that comprises the first conduit around which is wound the second conduit. Auxiliary steam from the auxiliary boiler flows through the second conduit thereby to heat the fluid flowing through the first conduit. However, in other embodiments, a temperature increase of fluid within the steam generation section is achieved in a different way. For example, the heat transfer section may be configured in a different way.

[00107] By way of example, FIG. 5 is a schematic illustration showing a schematic illustration of a further embodiment of a power plant, hereinafter referred to as the further power plant 500 [00108] The elements of the further power plant 500 that are common to both the further power plant 500 and the power plant 102 are identified with like reference numerals and configured as described in more detail earlier above with reference to FIG. 3 [00109] In this embodiment, the heat transfer section 210 comprises a heat exchanger 502 and an eighth valve 504.

[00110] The heat exchanger 502 may be any appropriate type of heat exchanger.

The heat exchanger 502 is arranged between the BCP 204 and the steam generation panels 218. The heat exchanger 502 is configured to transfer heat from the auxiliary steam following through the second conduit 232 to the fluid flowing within the first conduit 231.

[00111] In this embodiment, the BCP 204 is further fluidly connected to the steam generation panels 218 via a further conduit, hereinafter referred to as the -further bypass conduit" 506. The further bypass conduit 506 fluidly connects the BCP 204 to the steam generation panels 218 in a way that bypasses the heat exchanger 502 such that fluid pumped from the BCP 204 to the steam generation panels may bypass the heat exchanger 502. The eighth valve 504 is disposed along the further bypass conduit 506 and is configured to control and/or regulate the flow of fluid from the BCP 204 to the steam generation panels 218 via the further bypass conduit 506. In this embodiment and as shown in FIG. 5, a further valve 507 may be located along the first conduit 231, for example, at or proximate to the inlet of the heat exchanger 502. The eighth valve 504 and the further valve 507 may be operated to control and/or regulate fluid flow through the heat exchanger 502, via the first conduit 231. For example, the eighth valve 504 may be closed and the further valve 507 may be opened, thereby to prevent fluid flow through the further bypass conduit 506 and to cause said fluid to flow through the heat exchanger 502, whereby it is heated. Similarly, the eighth valve 504 may be opened and the further valve 507 may be closed, thereby to allow fluid flow through the further bypass conduit 506 and to cause said fluid to flow to bypass the heat exchanger 502.

[00112] As another example, FIG. 6 is a schematic illustration showing a schematic illustration of a further embodiment of a solar receiver, hereinafter referred to as the second further solar receiver 600. The second further solar receiver 600 may be implemented in the power plant 102 instead of or in addition to the solar receiver 108 and/or the further solar receiver 500.

[00113] The elements of the second further solar receiver 600 that are common to both the second further solar receiver 600 and the solar receiver 108 are identified with like reference numerals and configured as described in more detail earlier above with reference to FIG. 3 [00114] In this embodiment, the second conduit 232 is fluidly connected to the first conduit 231, such that the auxiliary steam produced by the auxiliary boiler 206 may flow into, and mix with, fluid within the first conduit 231.

[00115] Thus, the evaporation of water to steam within the steam generation section 112 is increased, thus increasing the volume flow rate of steam supplied to the superheater section 114.

[00116] The flow of auxiliary steam into the first conduit 231 may be controlled or regulated by the fifth valve 215, the seventh valve 217, and/or the first additional valve 251, or by any other control and/or regulation means.

[00117] In this embodiment, the auxiliary steam is introduced into the first conduit 231 at a position downstream of the BCP 204, i.e. between the BCP 204 and the steam generation panels 218 This advantageously tends to reduce or eliminate the likelihood of cavitation occurring within the BCP 204 caused by the introduction of the auxiliary steam into the fluid travelling through the steam generation section 112.

[00118] As shown in FIG. 6, the further solar receiver 600 may further comprise an additional conduit 602 fluidly connecting the drum 200 to the BDFT 208. A ninth valve 604 may be disposed along the additional conduit 602 to control and/or regulate the flow of fluid from the drum 200 to the BDFT 208. The ninth valve 604 may be controlled to allow fluid to be removed from the drum 200, for example in order maintain a desired (e.g. substantially constant) fluid volume or level within the drum 200 and/or steam generation section 112.

[00119] It will be appreciated by those skilled in the art that the additional conduit 602 and ninth valve 604 may be omitted. Also, the additional conduit 602 and ninth valve 604 may be implemented in any of the previously presented embodiments, such as those described in more detail earlier above with reference to FIGs. 3 and 5.

[00120] In the above embodiments, the heat transfer section is at a position downstream of the BCP, i.e. between the BCP and the steam generation panels. However, in other embodiments, the heat transfer section is located at a different position on either the first circulation path or the second circulation path. For example, in some embodiments, the heat transfer section is located upstream of the BCP, between the steam generation panels and the BCP [00121] In the above embodiments, the auxiliary boiler is fluidly connected to the second conduit via the bypass conduit, on which is disposed the seventh valve 217. However, in some embodiments, the bypass conduit and the seventh valve 217 are omitted.

[00122] In the above embodiments, the steam generation section and the superheater section are fluidly coupled via the drum. However, in other embodiments, the steam generation section and the superheater section are fluidly coupled together in a different way.

[00123] In the above embodiments, the system for startup or post-shutdown preparation of the power plant is implemented in a solar power plant. It will be appreciated by those skilled in the art that the system may be utilized in relation to any solar operated power plants or any other power plants (other than solar), arid is particularly useful for those that are subject to frequent startups and shutdowns.

[00124] It should be noted that certain of the process steps depicted in the flowcharts of FIGs. 3 and 4 and described above may be omitted or such process steps may be performed in differing order to that presented above and shown in FIGs. 3 and 4. Furthermore, although all the process steps have, for convenience and ease of understanding, been depicted as discrete temporally-sequential steps, nevertheless some of the process steps may in fact be performed simultaneously or at least overlapping to some extent temporally.

[00125] The foregoing descriptions of specific embodiments of the present disclosure have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments have been chosen and described in order to best explain the principles of the present disclosure and its practical application, to thereby enable others skilled in the art to best utilize the present disclosure and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the scope of the claims of the present disclosure.

Claims

CLAIMS1. A system comprising: a steam generation section; a superheater section; an auxiliary fluid source; an auxiliary fluid flow path and a heat transfer section; wherein the steam generation section comprises one or more steam generation components configured to generate steam from water flowing through the steam generation section, and to output the generated steam to the superheater section; the superheater section comprises one or more superheater components configured to heat the steam received from the steam generation section; the auxiliary fluid flow path is configured to convey an auxiliary fluid from the auxiliary fluid source to the one or more superheater components, for heating the one or more superheater components, the auxiliary fluid flow path is further configured to convey the auxiliary fluid from the auxiliary fluid source to the heat transfer section; the heat transfer section is configured to provide for heat transfer between the auxiliary fluid received via the auxiliary fluid flow path and the water flowing through the steam generation section.
2. The system of claim 1, wherein: the system is a solar power plant or a solar receiver of a solar power plant; the one or more steam generation components comprises one or more steam generation panels; and the one or more superheater components comprises one or more superheater panels.
The system of claim 1 or 2, wherein: the auxiliary fluid is steam; and the auxiliary fluid source comprises a boiler, a direct storage means, or an indirect storage means.
The system of any of claims Ito 3, wherein: the heat transfer section comprises: a first conduit, the first conduit being a conduit of the steam generation section through which water flows; and a second conduit through which the auxiliary fluid flows; and at least a part of the second conduit is wound around at least part of the first conduit, or vice versa.
5. The system of any of claims I to 4, wherein the heat transfer section comprises a heat exchanger.
6. The system of any of claims I to 5, wherein the heat transfer section is configured to permit the auxiliary fluid to flow into a conduit that is arranged to carry the water within the steam generation section.
The system of claim 6, wherein: the steam generation section comprises a pump configured to pump water through the steam generation section; and the heat transfer section is configured to permit the auxiliary fluid to flow into the conduit that is arranged to carry the water within the steam generation section at a position downstream of the pump in a direction in which the water is pumped.
8. The system of claim 6 or 7, further comprising means for removing water from the steam generation section responsive to the auxiliary fluid being introduced into the conduit that is arranged to carry the water within the steam generation section.
9. The system of any of claims 1 to 8, wherein the auxiliary fluid flow path is configured to convey an auxiliary fluid from the auxiliary fluid source to the one or more superheater components and then from the one or more superheater components to the heat transfer section.
10. The system of any of claims 1 to 9, further comprising a bypass conduit arranged to permit a flow of the auxiliary fluid from the auxiliary fluid source to the heat transfer section which bypasses the one or more superheater components.
11. The system of any of claims 1 to 10, further comprising a flash tank, wherein the auxiliary fluid flow path is further configured to convey the auxiliary fluid from the heat transfer section to the flash tank.
12. The system of any of claims 1 to 11, further comprising: a drum, fluidly connected between the steam generation section and the superheater section; and a water source configured to supply liquid water to the drum; wherein the drum is arranged to: output liquid water to the steam generation section; receive liquid water and/or steam from the steam generation section; and output the received steam to the superheater section.
13. A method for performance by a system, the system comprising a steam generation section, an auxiliary fluid source, and a heat transfer section, the method comprising: outputting, by the auxiliary fluid source, an auxiliary fluid; causing the auxiliary fluid to flow from the auxiliary fluid source to the heat transfer section; transferring, by the heat transfer section, heat from the auxiliary fluid to water flowing through the steam generation section; and causing the heated water to flow through the heat transfer section, thereby to heat one or more steam generation components of the steam generation section.
14. The method of claim 13, wherein the system further comprises a superheater section, and the method further comprises causing the auxiliary fluid to flow from the auxiliary fluid source to one or more superheater components of the superheater section, thereby to heat the one or more superheater components.
15. The method of claim 13 or 14, wherein: the system is a solar power plant or a solar receiver of a solar power plant; and the method is performed at least during a startup operation of the solar power plant
16. A method for performance by a system, the system comprising a steam generation section, a superheater section, an auxiliary fluid source, and a heat transfer section, wherein the steam generation section comprises one or more steam generation components configured to generate steam from water flowing through the steam generation section and to output the generated steam to the superheater section, the method comprising: outputting, by the auxiliary fluid source, an auxiliary fluid; causing the auxiliary fluid to flow from the auxiliary fluid source to the heat transfer section, the flow of the auxiliary fluid bypassing the superheater section; transferring, by the heat transfer section, heat from the auxiliary fluid to water flowing through the steam generation section, thereby to heat the water and to increase steam production by the one or more steam generation components of the steam generation section
17. The method of claim 16, wherein the system is a solar receiver of a solar power plant, and the method is performed in low load operation of the solar power plant responsive to a detection of low solar light levels or low direct normal irradiance (DNI).
18. The method of any of claims 13 to 17, wherein the system is the system of any of claims t to 12.