Patent Application
20150135713
1. Technical Field
The disclosure is related generally to turbine system. More particularly, the disclosure is related to a steam turbine system and a steam turbine control system for the steam turbine system.
2. Related Art
Conventional steam turbine systems are frequently utilized to generate power for electric generators. More specifically, a working fluid, such as steam, is conventionally forced across sets of steam turbine blades, which are coupled to the rotor of the steam turbine system. The force of the working fluid on the blades causes those blades (and the coupled body of the rotor) to rotate. In many cases, the rotor body is coupled to the drive shaft of a dynamoelectric machine such as an electric generator. In this sense, initiating rotation of the steam turbine system rotor can initiate rotation of the drive shaft in the electric generator, and cause that generator to generate an electrical current (associated with power output).
The amount of power generated by the steam turbine during operation, and ultimately the efficiency of the steam turbine, oftentimes stated in the form of ‘heat rate’, may be dependent upon a plurality of factors. For example, one such factor may include the efficiency of the condenser of the steam turbine system. The condenser may be responsible for receiving exhaust steam that has flowed through the various sections (e.g., high-pressure section, low-pressure section) of the steam turbine system, and converting the exhaust steam to fluid. The fluid may be subsequently converted back to steam and flowed through the various sections of the steam turbine system again. When exhaust steam enters the condenser at an undesirable temperature (e.g., higher than optimum conversion temperature), a portion of the exhaust steam may be removed from or rejected by the condenser in order for the condenser to convert all of the exhaust steam to fluid. The overall efficiency of the steam turbine system may be reduced when a portion of the exhaust steam is rejected by the condenser. To compensate for this loss in efficiency, larger condensers are used in the steam turbine system, such that less exhaust steam having an undesirable temperature may be rejected. However, a larger condenser requires an increased power requirement for operation, and also increases the size of the steam turbine system.
An additional factor that may affect the efficiency of the steam turbine system is the temperature of the fluid prior to reaching the boiler of the steam turbine system. That is, the overall efficiency of the steam turbine system may be directly affected by the temperature of the fluid just prior to the fluid reaching the boiler and subsequently being converted to operational steam. The greater the difference between the actual fluid temperature and a desired conversion temperature, the greater the power requirement for the boiler to convert the fluid to steam. That is, as the difference between the actual fluid temperature and the desired conversion temperature increases, the power required to convert the fluid to steam also increases, increasing the heat rate of the steam turbine system. The power required by the boiler to convert the fluid to steam may be generated from other portions of the steam turbine system, which may result in a decrease in power generated by the steam turbine system, and ultimately may decrease the efficiency of the steam turbine system.
A steam turbine system and a steam turbine control system are disclosed. In one embodiment the steam turbine system includes: an auxiliary turbine in fluid communication with an intermediate-pressure (IP) turbine of the steam turbine system via an IP exhaust conduit; and a heat exchanger system coupled to the steam turbine system, the heat exchanger system for removing heat from an IP exhaust steam flowing through the IP exhaust conduit, and adding the removed heat to water flowing through a boiler feed-water conduit to a boiler of the steam turbine system.
A first aspect of the invention includes a steam turbine system comprising: an auxiliary turbine in fluid communication with an intermediate-pressure (IP) turbine of the steam turbine system via an auxiliary turbine inlet conduit branch of an IP exhaust conduit; and a heat exchanger system coupled to the steam turbine system, the heat exchanger system for removing heat from IP exhaust steam flowing through the auxiliary turbine inlet conduit, and adding the removed heat to water flowing through a boiler feed-water conduit to a boiler of the steam turbine system.
A second aspect of the invention includes a steam turbine control system comprising: a diagnostic system configured to: determine a heat rate of the steam turbine system; and modify an amount of heat removed from an intermediate-pressure (IP) steam turbine exhaust steam flowing through an auxiliary turbine inlet conduit and added to a boiler feed-water conduit to a boiler of the steam turbine system by a heat exchanger system to minimize the heat rate of the steam turbine system.
A third aspect of the invention includes a steam turbine system comprising: an auxiliary turbine in fluid communication with an intermediate-pressure (IP) turbine of the steam turbine system via an auxiliary turbine inlet conduit branch of an IP exhaust conduit; a heat exchanger system coupled to the steam turbine system, the heat exchanger system for removing heat from an IP exhaust steam flowing through the auxiliary turbine inlet conduit, and adding the removed heat to water flowing through a boiler feed-water conduit to a boiler of the steam turbine system; and a steam turbine control system including: a diagnostic system operably connected to the heat exchanger system, the diagnostic system configured to: determine a heat rate of the steam turbine system; and modify the amount of heat removed from the IP exhaust steam flowing through the auxiliary turbine inlet conduit and added to the boiler feed-water conduit by the heat exchanger system to minimize the heat rate of the steam turbine system.
These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various embodiments of the invention, in which:
It is noted that the drawings of the invention are not necessarily to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings.
As discussed herein, aspects of the invention relate generally to steam turbine systems. More particularly, as discussed herein, aspects of the invention relate to a steam turbine system and a steam turbine control system.
Turning to
During operation of steam turbine system 10, operational steam may be supplied to steam turbine component 12 via steam inlet conduit 24. More specifically, as shown in
IP turbine section 16 may include an IP exhaust conduit for moving IP exhaust steam out of IP turbine section 16 of steam turbine component 12. As shown in
As shown in
It is understood that first heat exchanger system 36 of heat exchanger system 35, as shown in
Auxiliary turbine inlet conduit 32 may also fluidly couple IP turbine section 16 of steam turbine component 12 to an auxiliary turbine 39 of steam turbine system 10. That is, steam turbine system 10 may include auxiliary turbine 39 in fluid communication with IP turbine section 16 via auxiliary turbine inlet conduit 32. As shown in
Steam turbine system 10, as shown in
Steam turbine system 10 may also include a boiler feed-water conduit 50 fluidly coupling condenser 44 with a boiler 52. More specifically, as shown in
As shown in
By allowing second heat exchanger 54 of heat exchanger system 35 to increase the temperature of the water using the removed heat from the IP exhaust steam, boiler 52 may not require as much energy or power to convert the water to operational steam for steam turbine component 12, as discussed herein. That is, by utilizing the removed heat from the IP exhaust steam of IP turbine section 18, the water entering boiler 52 may have a temperature that is substantially higher than the temperature of the water as it immediately flows from condenser 44 into boiler feed-water conduit 50. As a result, the temperature of the water entering boiler 52 may be substantially equal to or slightly higher than a temperature for converting the water to operational steam, which may ultimately allow boiler 52 to convert the water to operational steam at a reduced energy or power requirement, reducing the heat rate of steam turbine system 10.
As shown in
As shown in
As shown in
As discussed herein, diagnostic system 108 of control system 100 may be configured to determine a heat rate of steam turbine system 10, and modify the amount of heat removed from the IP exhaust steam flowing through auxiliary turbine inlet conduit 32 and added to boiler feed-water conduit 50 by heat exchanger system 35 to minimize the heat rate (i.e., increase the efficiency) of the steam turbine system. As discussed herein, diagnostic system 108 of control system 100 may be configured to modify the heat exchanger system 35 to one of increase or decrease the amount of heat removed from the IP exhaust steam flowing through auxiliary turbine inlet conduit 32 in response to the heat rate of the steam turbine system increasing.
Turning to
Referring to
HR=(m_HP_inlet*(H_HP_inlet−H_ffw)+m_IP_inlet*(H_IP_inlet−H_HP_exh))/GEN kW,
where m_HP_inlet is mass flow of inlet steam to HP turbine section 14, H_HP_inlet is enthalpy of inlet steam to HP turbine section 14, H_ffw is enthalpy of inlet water at the final feedwater (ffw) location at the inlet to boiler 52, m_IP_inlet is mass flow of inlet steam to IP turbine section 16, H_IP_inlet is enthalpy of inlet steam to IP turbine section 16, H_HP_exh is enthalpy of exhaust steam from HP turbine section 14, and GEN kW is the power output of generator 22. Based on the foregoing, heat rate is determined using pressure and temperature measurements in the dry region of the steam turbine (i.e. HP and IP sections) along with measured generator output.
With continuing reference to
In addition to determining heat rate, heat rate module 110 may also determine whether a heat rate of the steam turbine system 10 is increasing, i.e., relative to a previously calculated heat rate. Adjustment module 112 may be configured to adjust heat exchanger system 35 (e.g., via control valves and other equipment) to modify the amount of heat removed from auxiliary turbine inlet conduit 32 and added to boiler feed-water conduit 50, i.e., to water flowing through the conduit to boiler 52. More specifically, adjustment module 112 may be configured to determine how to adjust heat exchanger system 35, i.e., increase or decrease heat removal.
Adjustment module 112 of diagnostic system 108 may be configured to receive or obtain an indicator from heat rate module 110 in response to determining that the heat rate has increased or decreased, i.e., from a previously calculated heat rate, and may modify heat exchanger system 35 accordingly. More specifically, adjustment module 112 of diagnostic system 108 may receive or obtain the indicator from heat rate module 110 and may modify first heat exchanger 36 and/or second heat exchanger 54 of heat exchanger system 35 to increase or decrease the amount of heat removed from the IP exhaust steam flowing through auxiliary turbine inlet conduit 32. Adjustment module 112 may modify the amount of heat transmitting fluid used in first heat exchanger 36 and/or second heat exchanger 54 of heat exchanger system 35 to increase or decrease the amount of heat removed/added from the IP exhaust steam flowing through auxiliary turbine inlet conduit 32. For example, and as discussed herein, adjustment module 112 of diagnostic system 108 may be operably connected to a regulating component 38 of first heat exchanger 36, and may send an electronic signal to regulating component 38 of first heat exchanger 36 to modify regulating component 38. Regulating component 38 may be an adjustable valve positioned within inlet conduit 37, where heat rate module 112 may modify a position (e.g., open, closed, partially open) of the valve forming regulating component 38. In modifying the position of regulating component 38 of first heat exchanger 36, adjustment module 112 may modify the amount of heat transmitting fluid supplied to first heat exchanger 36, which may ultimately increase or decrease the amount of heat removed from IP exhaust steam flowing through first heat exchanger 36 via auxiliary turbine inlet conduit 32. Similar structure and functioning may be employed with second heat exchanger 54.
As discussed herein with respect to heat rate module 110, adjustment module 112 may be configured to modify heat exchanger system 35 to increase or decrease the amount of heat removed from the IP exhaust steam based, at least in part, upon operational characteristics of steam turbine system 10 that impact heat rate, and the operational characteristics of auxiliary turbine 39, which may determine the anticipated heat transfer or heat loss, adjustment module 112 may modify first heat exchanger 36 of heat exchanger system 35 to increase or decrease the amount of heat removed from the IP exhaust steam. Additionally, the heat transfer or heat loss may be calculated using a conventional heat transfer equation, the determined temperature of the auxiliary exhaust steam and knowing the operational characteristics of auxiliary turbine 39. As discussed herein, the operational characteristics of auxiliary turbine 39 that may aid in determining the heat transfer or heat loss in auxiliary turbine 39 may include, but are not limited to: the size of auxiliary turbine 39, the power output of auxiliary turbine 39, the temperature of the IP exhaust steam flowing through auxiliary turbine 39, etc. A number of examples of diagnostic system 108 operation will now be described. In an embodiment, where heat rate module 110 determines heat rate is increasing, adjustment module 112 may modify first exchanger 36 of heat exchanger system 35 to increase the amount of heat removed from IP exhaust steam. Adjustment module 112 may modify the position of regulating component 38 of first heat exchanger 36 to increase the amount of heat removed from the IP exhaust steam flowing through auxiliary turbine inlet conduit 32. Adjustment module 112 may modify first heat exchanger 36 of heat exchanger system 35 to increase the amount of heat removed from the IP exhaust steam by modifying the position of regulating component 38 of first heat exchanger 36 to be open or partially open. Where regulating component 38 is substantially open, a maximum amount of heat transmitting fluid of first heat exchanger 36 may be provided to first heat exchanger 36 to substantially cool IP exhaust steam flowing through auxiliary turbine inlet conduit 32 prior to the IP exhaust steam flowing through auxiliary turbine 39.
By utilizing heat exchanger system 35 and/or control system 100, as discussed herein, heat rate may be minimized. As a result, condenser 44 may substantially decrease or eliminate the amount of auxiliary exhaust steam rejected during operation of steam turbine system 10. The decrease or elimination of rejected auxiliary exhaust steam may ultimately increase the efficiency of condenser 44 and also minimize heat rate, i.e., increase the overall operational efficiency of steam turbine system 10. Also, by decreasing or eliminating the rejection of a portion of the auxiliary exhaust steam, condenser 44 of steam turbine system 10 may be smaller in size, which may also decrease the overall size or space requirement for steam turbine system 10. Furthermore, where the size of condenser 44 may be reduced as a result of utilizing heat exchanger system 35 and/or control system 100, the costs associated with condenser 44 (e.g., manufacturing, transporting, installation) may also be reduced. Additionally, in utilizing heat exchanger system 35 and/or control system 100, and more specifically, removing and adding heat to the water of the steam turbine system 10 via heat exchanger system 35, boiler 52 of steam turbine system 10 may heat the water and/or convert it to operational steam more quickly and/or with a decreased power requirement. As a result, boiler 52 may also become more efficient during operation, which may also increase the overall operational efficiency of steam turbine system 10.
Diagnostic system 108, and its respective components (e.g., heat rate module 110, adjustment module 112), may be configured as any conventional data processing system (e.g., computer system, hard drives) capable of receiving, temporarily storing and transmitting/forwarding data and signals within the system and to external components coupled to the system (e.g., first heat exchanger 36). More specifically, diagnostic system 108 of control system 100 may be configured as any conventional hardware device (computer system controller), and the components of diagnostic system 108 (e.g., heat rate module 110, adjustment module 112) may be configured as software components stored within said computer system forming diagnostic system 108. In an example embodiment, diagnostic system 108 may be configured as a circuit board implemented on a conventional computer system, and may include associated software for performing the operational functions discussed herein. Additionally, it is understood that control system 100 may also be included in a control system (not shown) for the entire steam turbine system 10. That is, control system 100, as discussed herein, may be included within the control system configured to operate steam turbine system 10 and its various components (e.g., turbine component 12, condenser 44, boiler 52, etc.).
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. 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.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
