System and method for heating feedwater using a solar heating system   

BACKGROUND OF THE INVENTION

The present invention relates to the feedwater consumed by a boiler during operation or a steam turbine; and more particularly to a system and method of incorporating a solar heating system to heat the feedwater.

A powerplant incorporating a steam turbine is typically integrated with a condensor and a boiler. The condensor receives the low energy steam, or steam-water mixture, discharged by the steam turbine. After receiving the low energy steam, the condensor extract heat from the steam, which condenses to form feedwater. The boiler receives and heats the feedwater until conversion to steam, which is sent to the steam turbine, and this closed loop process is repeated. Some boilers, such as, but not limiting of, a heat recovery steam generator (HRSG) heat the feedwater with energy from the exhaust of a gas turbine. Other boilers heat the feedwater via steam extracted from the steam turbine. Both of these approaches to heating the feedwater reduce the output of the powerplant.

Solar power is a renewable energy source whose application and usage is on the rise. Solar power usage can be advantageous in regions where turbomachines are exposed to a sufficient amount of sunlight. Some of the benefits of using solar power include, but are not limited to: increase in the output and efficiency of the turbomachine and a reduction in turbomachine emissions. The efficiency of solar power systems varies on the type of solar technology used. This variance can make the addition of solar technology to a turbomachine site cost prohibitive. If a solar power system can be configured to heat the feedwater, then the steam that is customarily used for feedwater heating will be available to produce power.

For the foregoing reasons, there is a need for a system that reduces the parasitic load associated with heating the feedwater consumed by a boiler. The system should incorporate a relatively efficient solar technology to increase the temperature of the feedwater.

In accordance with an embodiment of the present invention, a system for increasing a temperature of a feedwater, the system comprising: a steam turbine configured for converting steam into mechanical energy: a condensor integrated with the steam turbine, wherein the condensor is configured for transferring steam discharged from the steam turbine into feedwater; and a solar heating system configured for heating the feedwater, wherein the solar heating system receives the feedwater discharged from the condensor; wherein the solar heating system heats the feedwater from a first temperature to a second temperature.

In accordance with an alternate embodiment of the present invention, a powerplant configured for increasing a temperature of a feedwater, the powerplant comprising: a steam turbine configured for converting steam into mechanical energy; a condensor integrated with the steam turbine, wherein the condensor is configured for transferring the steam discharged from the steam turbine into feedwater; a solar heating system configured for heating the feedwater, wherein the solar heating system receives the feedwater discharged from the condensor; wherein the solar heating system heats the feedwater from a first temperature to a second temperature; and a boiler configured for converting the feedwater to steam, wherein the boiler receives the feedwater, at the second temperature, which is discharged by the solar heating system, and wherein the boiler discharges the steam to the steam turbine; wherein the solar heating system reduces an amount of work performed by the boiler in heating the feedwater to a temperature allowing for conversion of the feedwater to steam; increasing an overall efficiency of a powerplant.

In accordance with an another alternate embodiment of the present invention, a method of increasing a temperature of a feedwater, the method comprising: providing a steam turbine, wherein the steam turbine is configured for converting steam into mechanical energy; providing a condensor integrated with the steam turbine, wherein the condensor is configured for condensing the steam discharged from the steam turbine into feedwater; providing a solar heating system configured for heating the feedwater, wherein the solar heating system receives the feedwater discharged from the condensor; and operating the solar heating system to heat the feedwater from a first temperature to a second temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustrating an environment in which an embodiment of the present invention may operate.

FIG. 2 is a schematic illustrating an example of a solar heating system in accordance with an embodiment of the present invention.

FIG. 3 is a schematic illustrating an example of a solar heating system in accordance with an alternate embodiment of the present invention.

DETAILED DESCRIPTION

The following detailed description of preferred embodiments refers to the accompanying drawings, which illustrate specific embodiments of the invention. Other embodiments having different structures and operations do not depart from the scope of the present invention.

Detailed example embodiments are disclosed herein. However, specific structural and functional details disclosed herein are merely representative for purposes of describing example embodiments. Example embodiments may, however, be embodied in many alternate forms, and should not be construed as limited to only the embodiments set forth herein.

Accordingly, while example embodiments are capable of various modifications and alternative forms, embodiments thereof are illustrated by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit example embodiments to the particular forms disclosed, but to the contrary, example embodiments are to cover all modifications, equivalents, and alternatives falling within the scope of example embodiments.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any, and all, combinations of one or more of the associated listed items.

The terminology used herein is for describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes” and/or “including”, when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It should also be noted that in some alternative implementations, the functions/acts noted might occur out of the order noted in the FIGS. Two successive FIGS for example, may be executed substantially concurrently or may sometimes be executed in the reverse order, depending upon the functionality/operations involved.

Certain terminology is used herein for the convenience of the reader only and is not to be taken as a limitation on the scope of the invention. For example, words such as “upper,” “lower,” “left,” “right,” “front”, “rear” “top”, “bottom”, “horizontal,” “vertical,” “upstream,” “downstream,” “fore”, “aft”, and the like; merely describe the configuration shown in the Figures. Indeed, the element or elements of an embodiment of the present invention may be oriented in any direction and the terminology, therefore, should be understood as encompassing such variations unless specified otherwise.

The present invention may be applied to the variety of powerplants that have a steam turbine, such as, but not limiting of, a combined cycle powerplant, a co-generation powerplant, an individual steam turbine plant; or the like. An embodiment of the present invention may be applied to either a single steam turbine or a plurality of steam turbines.

An embodiment of the present invention takes the form of a system and method that may use at least at least one solar heating system to heat the feedwater consumed by a boiler, such as, but not limiting of, a HRSG. The elements of the present invention may be fabricated of any material that can withstand the operating environment under which the solar heating system may function and operate.

An embodiment of the present invention may incorporate a concentrated solar power (CSP) system. Generally, CSP systems incorporate a plurality of lenses, mirrors, or combinations thereof and a tracking system to focus a large area of sunlight forming a small concentrated beam of light. The concentrated light may then be used as a heat source. In an embodiment of the present invention, the heat source may be used to partially or completely heat the feedwater consumed by the HRSG. CSP systems may take the form of a solar trough system, a parabolic dish system, a solar power tower system, or the like.

Referring now to the Figures, where the various numbers represent like elements throughout the several views, FIG. 1 is a schematic illustrating an environment in which an embodiment of the present invention may operate. FIG. 1 illustrates a combined-cycle powerplant that includes a gas turbine 100 in a combined cycle configuration, and at least one solar heating system 175. The gas turbine 100 generally comprises a compressor 105, a combustion system 110, and a turbine section 115. A stack 140 may be located downstream of the turbine section 115.

Generally, the compressor 105 receives and compresses an inlet air, represented by an arrow in FIG. 1. The compressed air may flow downstream to the combustion system 110, where the compressed air is mixed with a fuel (not illustrated), such as, but not limiting of, a natural gas, and is then combusted. The energy released during the combustion process flows downstream and drives the turbine section 115. A load, such as, but not limiting of, a generator 125 may be coupled to the gas turbine 100, wherein the mechanical torque generated in the turbine section 115 may drive the generator 125.

The exhaust 120 generated during the operation of the gas turbine 100 may flow downstream towards a heat recovery steam generator (HRSG) 135. The HRSG 135 may incorporate a heat exchanging process to transform a feedwater 165 into steam 145. Here, an embodiment of the present invention uses the solar heating system 175 to heat (partially or completely) the feedwater 165. The steam 145 may flow downstream to a steam turbine 150, which may be coupled to a load, such as, but not limiting of, a generator 155. During the operation of the steam turbine 150, the steam 145 may condense in a condensor 160, forming the feedwater 165. Here, in some powerplant configuration, an extraction from the steam turbine 150 may partially heat the feedwater. A pump 170, such as, but not limiting of, a boiler feed pump, may drive the feedwater 165 into the HRSG 135, where the aforementioned process may be repeated. After flowing through the HRSG 135, the exhaust 120 may flow through the stack 140.

A first embodiment of the a solar heating system 175 may comprise a parabolic trough system 200, as illustrated in FIGS. 1 and 2. An embodiment of the parabolic trough system 200 may comprise a plurality of linear parabolic reflectors 205 that concentrate the sunlight onto a receiver 210 positioned along a focal line of the parabolic reflectors 205. The linear parabolic reflectors 205 are designed to follow the sunlight during the daylight hours by tracking along at least one axis (not illustrated in the FIGS.). The receiver 210 may comprise a pipe through which the feedwater 165 may flow. Here, the solar heating system 175 may heat the feedwater 165 via a convection form of heat transfer, such as, but not limiting of, forced convection, natural convection, or the like.

A second embodiment of the solar heating system 175 may comprise a solar tower system 300, as illustrated in FIG. 3. An embodiment of the solar tower system 300 may incorporate a plurality of tracking reflectors 305 for concentrating sunlight light onto a central receiver 310 near the top of a tower 315. The receiver 310 may comprise a pipe through which the feedwater 165 may flow. Here, the solar heating system 175 may heat the feedwater 165 via a convection form of heat transfer, such as, but not limiting of, forced convection, natural convection, or the like.

In use, the at least one solar heating system 175 may heat the feedwater 165 from a first temperature to a second temperature. Here, the first temperature may be considered the temperature of the feedwater 165 existing the condensor 160. In an embodiment of the present invention, the first temperature may be up to about 150 degrees Fahrenheit. Furthermore, the second temperature may be considered the heated temperature of the feedwater 165. In an embodiment of the present invention, the second temperature may be up to about 700 degrees Fahrenheit.

The at least one solar heating system 175 may provide a user with a plurality of benefits. In an embodiment of the present invention the at least one solar heating system 175 may provide up to about 8 megawatts of equivalent power generated by a typical heavy duty turbomachine. In an embodiment of the present invention, the at least one solar heating system 175 may have an efficiency of up to about 85%.

An embodiment of the present invention may provide a control system for operating a configuration integrating the solar heating system 175 and the HRSG 135 in manner for collectively heating the feedwater 165. Here, the control system may determine the amount of heat necessary to convert the feedwater 165 to steam. Next, the control system may determine the amount of heat currently available by the solar heating system 175 and the remaining heat necessary, if any, to be provided by the HRSG 135. Next, the control system may operate this configuration such that the maximum amount of heat available from the solar heating system 175 is used to heat the feedwater 165, with the remaining heat deriving from the HRSG 135, if any.

An alternate embodiment of the present invention may provide a control system for operating a configuration integrating the solar heating system 175 and an extraction of the steam turbine 150 in manner for collectively heating the feedwater 165. Here, the control system may determine the amount of heat necessary to convert the feedwater 165 to steam. Next, the control system may determine the amount of heat currently available by the solar heating system 175 and the remaining heat necessary, if any, to be provided by the steam turbine 150. Next, the control system may operate this configuration such that the maximum amount of heat available from the solar heating system 175 is used to heat the feedwater 165, with the remaining heat deriving from the steam turbine 150, if any.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Although specific embodiments have been illustrated and described herein, it should be appreciated that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiments shown and that the invention has other applications in other environments. This application is intended to cover any adaptations or variations of the present invention. The following claims are in no way intended to limit the scope of the invention to the specific embodiments described herein.

As one of ordinary skill in the art will appreciate, the many varying features and configurations described above in relation to the several exemplary embodiments may be further selectively applied to form the other possible embodiments of the present invention. Those in the art will further understand that all possible iterations of the present invention are not provided or discussed in detail, even though all combinations and possible embodiments embraced by the several claims below or otherwise are intended to be part of the instant application. In addition, from the above description of several exemplary embodiments of the invention, those skilled in the art will perceive improvements, changes, and modifications. Such improvements, changes, and modifications within the skill of the art are also intended to be covered by the appended claims. Further, it should be apparent that the foregoing relates only to the described embodiments of the present application and that numerous changes and modifications may be made herein without departing from the spirit and scope of the application as defined by the following claims and the equivalents thereof.