GB2152591A

GB2152591A - Steam turbine-generator thermal performance monitor

Info

Publication number: GB2152591A
Application number: GB08431125A
Authority: GB
Inventors: Jens Kure-Jensen; Harris Stanley Shafer
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1983-12-19
Filing date: 1984-12-10
Publication date: 1985-08-07
Also published as: JPH0336125B2; FR2556773A1; CH680008A5; DE3445791A1; KR910004915B1; JPS60192807A; DE3445791C2; IT1177447B; CA1246667A; KR850004297A; IT8424114A0; GB8431125D0; GB2152591B; FR2556773B1

Description

GB 2 152 591A 1

SPECIFICATION

Steam turbine-generator thermal performance monitor Background of the Invention The present invention relates to steam turbines and, more particularly, to thermal performance monitors for evaluating the instantaneous performance of steam turbine-generator systems.

Large steam turbine-generator systems represent major capital invediments for their owners and their economic benefit to the owners varies with the thermal efficiency with which the steam turbines are operated. To highlight the importance of thermal efficient operation, it is 10 believed that a difference of one percent in the efficiency of a steam turbine driving a one gigawatt electric generator is worth on the order of tens of millions of dollars over the life of the unit. Thus, the owners of a large steam turbine-generator are vitally interested in maintaining the operating parameters of the system as close as possible to the optimum set of operating parameters as designed for the system, and/or developed during operational testing following 15 initial installation of the system, since departure from these parameters tends to reduce the thermal efficiency. In addition, unavoidable degradation in performance over time can occur due to deterioration of internal parts and other causes. Means for detecting the onset and severity of such deterioration is useful. Furthermore, it is desirable to monitor the turbine for internal problems, especially the type which necessitate rapid detection thereby permitting timely action 20 to be taken.

Despite the importance of maintaining the operating parameters at levels which maximize thermal efficiency, in normal practice, encompassing the minute-to-minute control of the controllable parameters of a large steam turbine, the turbine shift operators customarily maintain such operating parameters at values close to optimum levels but still far enough different from the optimum to produce substantial efficiency deviations which result in cost penalties.

Additionally, conventional power station instrumentation does not provide a class of information which has either the accuracy or the information content to guide an operator in adjusting and keeping a steam turbine at its best performance levels. In fact, it is possible, during the attempt to optimize system performance using monitoring systems of the prior art, for the shift operator 30 to make adjustments which, instead of changing the operating paran;eters in the direction of improved efficiency, change the operating parameters in directions resulting in degraded efficiency.

As part of the installation procedure of a steam turbine-generator subsystem, it is customary for the owners and/or the contractor or turbine manufacturer to conduct very accurate tests to 35 demonstrate or determine the heat rate of the system. Heat rate is a measure of thermal efficiency of a steam turbine-generator system defined as the number of units of thermal input per unit of electrical power output. In one convenient system of units, heat rate is measured in BTUs per kilowatt hour of power output. One standard test of heat rate is known as the ASME test and is defined in an ASME publication ANSI/ASME PTC 6-1976 Steam Turbines. A 40 simplified ASME test is described in A Simplified ASME Acceptance Test Procedure for Steam Turbines, presented at the Joint Power Conference, September 30, 1980, in Phoenix, Arizona.

A requirement and characteristic of both of the above tests is accurate instrumentation for temperatures, pressures and flows within a steam turbine along with the resulting generator power output to determine accurately the energy content of such conditions and the resulting 45 power output. The accuracy of measurement is sufficiently great that no measurement tolerance need be applied to the results. Such tests are costly to perform. For example, the standard ASME test requires a substantial installation of specialized measuring equipment at a substantial cost in conjunction with a great amount of manpower to administer the test. Thus, economic reality keeps the administration of such tests limited to the initial commissioning of a new steam 50 turbine-generator system and (less frequently) to the recommissioning of a steam turbine generator system at a subsequent time after a refurbishment.

Besides their cost, ASME-type tests have the additional drawback that they are not suitable fc)f use in day-to-day operation of a steam turbine-generator system. The types of instrumentation required may not retain useful accuracy over extended periods. In addition, even if such testing could be conducted on a substantially concurrent, instantaneous and daily basis, the type of information conventionally produced during such tests, although invaluable in the initial engineering evaluation of the system, is of a type which requires such substantial interpretation and calculation to derive control adjustments that it is, at best, of marginal value in guiding an operator in manipulating the controls which are available to him.

Customarily, the shift operator, directly controlling the steam turbine system, does not have the time, the inclination, nor the sophistication to reduce the technical results of the ASME-type tests into an understandable format on a substantially instantaneous basis. His primary function is to monitor the turbine-generator performance as it relates to other turbine-generator sets tied into the electrical transmission system. In this view, a thermal performance monitor must gather 65 2 GB 2 152 591 A 2 relatively instantaneous data from the turbine-generator system and present a limited amount of information-to the shift operator in a very concise, quickly readable and understandable format, such that the operator can adjust the turbine-generator set to operate more efficiently.

In contrast, a results engineer reviews the periodic performance statistics for the turbine generator set in a more sophisticated and detailed manner. Since the results engineer's attention 5 is not immediately focused on the steam pressures and temperatures and other parameters affecting the turbine, he can leisurely proceed with a more detailed analysis of the turbine's operation. From the results engineer's perspective, a detailed presentation at a much higher technical level of the thermal performance of each major component in the steam turbine generator system is desirable. As an example, the detailed thermal performance data compiled, 10 throughout one week of turbine operation, may illuminate an incipient problem with the steam condensor as reflected in an increased exhaust pressure value. By focusing his attention on the exhaust pressure vis-a-vis the other components of the turbine over an extended period of time, e.g., 2 months, the results engineer could approach the owners of the turbine-generator unit with a request for a cleaning or modification of the condensor. Further trend analysis would be 15 facilitated by a sophisticated thermal performance moditor.

ASME-type testing can, h-owever, be relied on initially to produce reference or a design data base from which optimum sets of operating parameters and the related heat rates and other parameters throughout a new steam turbine-generator system can be derived. Once such optimum sets of operating data are established, operating parameters during later operation of 20 the system may be compared to it for determining correct operation of the system.

Objects and Summary of the Invention

Accordingly, it is an object of the invention to provide an apparatus for guiding optimum operation of a steam turbine-generator system.

- It is a further object of the invention to provide an apparatus for instrumenting a steam turbine-generator system and for producing an output which may be used on a substantially instantaneous basis to control the controllable parameters of the steam turbine and obtain improved system efficiency.

It is a still further object of the invention to provide an apparatus for instrumenting a steam 30 turbine-generator system and for producing an output effective for directly informing an operator of the economic consequences of an existing set of operating parameters and for guiding the operator toward modifying the operating parameters in a direction tending to improve the system efficiency.

It is an additional object of this invention to provide for means for informing the results 35 engineer of detailed information and analysis regarding each major component in the steam flow path of the turbine-generator system.

It is a further object of the invention to provide an apparatus for instrumenting a steam turbine-generator system which is effective to monitor and display the thermal performance of each major component in the steam flow path of the turbine-generator system.

Summary of the Invention

A steam turbine-generator thermal performance monitor includes several sensors for measur ing the pressure and temperature of the steam in a steam turbine generator system. The position of the steam admission control valve is also sensed. An operator's thermal performance monitor obtains the pressure and temperature upstream of the control valve and the exhaust pressure of the steam downstream of the turbine. A power output signal from the electric generator is obtained and a means for determining the percentage of rated load at which the turbine is instantaneously operating at is also provided. An initial temperature heat rate correction factor is generated, in addition to an initial pressure heat rate correction factor and an exhaust pressure 50 heat rate correction factor. Means for determining the substantially instantaneous design heat rate for the turbine-generator system is provided which is based upon the temperature and pressure signals, the control valve position signal, and the design pressure and temperature values for the steam turbine. A main steam temperature loss signal is generated by multiplying the first temperature heat rate correction signal, the power signal, the design heat rate signal, 55 and a signal representativi of the cost per unit heat factor of operating the steam generator in the turbine-generator system. The main steam temperature loss signal is displayable in cost per unit time to the turbine operator. A steam pressure loss signal, also displayable in cost per unit time, is generated in a similar fashion utilizing a pressure heat rate correction signal and other signals. An exhaust pressure loss signal is generated by utilizing the exhaust pressure heat rate 60 correction signal and similar signals. The operator's monitor includes means for displaying, on a substantially continuous basis, the main steam temperature loss signal, the steam pressure loss signal and the exhaust pressure loss signal, all in cost per unit time format. This presentation informs the operators of the economic consequences of operating the turbine at the controllably selected temperature and pfessure and at a certain exhaust pressure.

3 GB 2 152591 A 3 The steam turbine-generator system may include a first, a second and a third turbine and additional temperature and pressure signals are generated and supplied to the monitor. A reheat steam temperature loss signal, displayable in cost per unit time, is summed with the first steam temperature loss signal to provide a total steam temperature loss signal. The displaying means presents the total steam temperature loss signal, in the cost per unit time format, to the operator of the steam turbine generator system.

A results engineer's thermal performance monitor measures the substantially instantaneous temperature and pressures throughout the steam turbine system. An ictual enthalpy drop and an isentropic enthalpy drop is calculated for the first, or high pressure turbine (hereinafter the HP turbine), and the second, or intermediate pressure turbine (hereinafter the IP turbine). The 10 substantially instantaneous design efficiencies for the HP turbine is calculated based upon the first temperature, first pressure, and the control valve position, in addition to the design pressure and temperature values for the HP turbine. The IP turbine has an installation dependent constant for its design efficiency. The actual efficiencies of the HP and IP turbine are calculated based upon the ratio of the actual enthalpy drops and the isentropic enthalpy drops. A pair of 15 deviation in heat rate from design calculators generate appropriate signals for the HP and W turbine respectively. Means for presenting the actual efficiencies of the HP and W turbine, the design efficiencies of the HP and IP turbine, and the HP and IP deviations in heat rate from design allows the results engineer to identify the overall performance of the turbine at a particular time.

The results engineer's thermal performance monitor may also include means for calculating a main steam temperature power loss, a main steam pressure power loss, a reheat steam temperature power loss, a turbine efficiency power loss, and an exhaust pressure power loss.

These power loss signals are presented to the results engineer and provide a basis for altering the operating parameters of the steam turbine-generator system, effecting the maintenance of 25 the system or recommending modifications of the system.

Brief Description of the Drawings

The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, together with 30 further objects and advantages thereof, may be best understood by reference to the following description taken in connection with the accompanying drawings in which;

Figure 1 is a simplified block diagram of a steam turbine-generator system according to an embodiment of the invention; Figure 2 is a simplified schematic diagram of a steam turbine-generator showing monitoring 35 points employed in the present invention; Figure 3 is a flow chart illustrating the functional aspects of an operator's thermal performance monitor as part of the data processing subsystem of Fig. 11; Figure 4 is an exemplary Initial Temperature Correction Factor Graph; Figure 5 is an exemplary Reheat Temperature Correction Factor Graph; Figure 6 is an exemplary Initial Pressure Correction Factor Graph; Figure 7 is an exemplary Exhaust Pressure Correction Factor Graph; Figure 8 illustrates an operator's display for the operator's thermal performance monitor; Figure 9 is a partial flow chart illustrating the functional aspects of the results engineer's thermal performance monitor as part of the data processing subsystem of Fig. 2; Figure 10 is the balance of the flow chart shown in Fig. 9, which further illustrates the functional aspects of a result engineer's m ' onitor; and Figure 11 illustrates a result engineer's display for the thermal performance monitor.

Detailed Description of an Embodiment

The principal controls available to a shift operator of a steam turbinegenerator system include boiler controls which determine the temperature and pressure of the main steam and reheat steam supplies and a main steam admission control valve or valves which determines the amount of steam admitted to the first or high pressure turbine stage. Practical guidance to an operator of such a steam turbine-generator system includes evaluations of the substantially instantaneous operating parameters in a manner which can be interpreted easily, quickly and without detailed technical analysis to facilitate the manipulation of these principal controls.

Referring now to Fig. 1, there is shown, generally a steam turbinegenerator system 10.

Steam turbine-generator system 10 includes a steam turbine-generator 12 receiving a thermal input from a steam boiler 14. Boiler 14 may be of any convenient type, such as coal-fired or oil- 60 fired. Both steam turbine-generator 12 and boiler 14 are controlled by operator inputs represented by a line 16 from an operator 18 to produce an electric power output represented by a line 20. A set of measured parameters from steam turbine-generator 12 are applied on a line 22 to a data processing subsystem 24. As will be more fully discussed hereinafter, the types of measured parameters are those which can be obtained with sufficient reliability and 4 GB2152591A 4 accuracy over the long term and which can be interpreted by data processing subsystem 24 in a fashion which can guide operator 18 in controlling steam turbine-generator 12 and boiler 14 on a minute-by- minute basis. The outputs of data processing subsystem 24 are applied to an operator interface subsystem 26 which may be of a conventional type such as, for example, a cathode ray tube display, a printer or other types of analog or digital display devices. The output from data processing subsystem 24, may also be applied to a data storage subsystem 28 wherein the data may be stored for short-term or long-term purposes. Data storage subsystem 28 may be of any convenient type including a printer, however, in the preferred embodiment, data processing subsystem 24 includes a digital processor and data storage subsystem 28 oreferably includes a digital storage device such as, for example a magnetic or optical disc or a 10 magnetic tape storage device.

Coupled parallelly with operator interface subsystem 26 is a results engineer interface subsystem 27. Interface 27 allow a results engineer 29 to study the outputs of data processing subsystem 24 on a more leisurely basis as compared with operator 18. Results engineer 29 communicates with operator 18 to improve the long-term performance of turbine-generator system 10 due in part to the higher level, sophisticated analysis with which the engineer views the data. The engineer also determines the maintenance procedures for the system and subsystem 27 assists in the promulgation of those procedures.

Referring now to Fig. 2, a simplified schematic diagram of steam turbinegenerator 12 is shown including only sufficient detail to fully disclose the present invention. Steam turbine- 20 generator 12 is conventional except for the measurement devices installed therein to support the present invention. Thus, a detailed description of steam turbinegenerator 12 is omitted. In general, the present invention relies on temperature and pressure measurements at various locations throughout steam turbine-generator system, including a measurement of the generated electrical power output and compares their relationship to corresponding design values to determine the power losses, efficiencies and heat rates throughout the system on a substantially instantaneous basis.

Steam turbine-generator 12, of Fig. 1, consists of a steam turbine 30 coupled through a mechanical connection 32, to an electric generator 34 which generates an electric power output. A transducer (not shown) in electric generator 34 produces an electric power output signal W1 which is applied to line 20 for transmission to data processing subsystem 24. The operator input on line 16 is applied by hydraulic, electrohydraulic, digital or other well known means, to a main control valve actuator 36 which affects a main control steam admission valve 38 as illustrated by line 40. A valve position signal V1, is generated by appropriate means and represents the amount by which main control valve 38 is opened, and the signal is applied to line 20 for transmission to data processing subsystem 24. It is to be understood that valve 38 is representative of a number of steam admission control valve commonly associated with a steam turbine.

A steam generator 42, which is part of boiler 14, produces a supply of hot pressurized steam which is applied to main control valve 38 on a line 44. The steam passing through main control 40 valve 38 is applied on a main steam line 46 to an input of a high pressure turbine 48. As utilized herein, the term---HP- refers to high pressure turbine 48. The steam exiting from HP turbine 48, now partially expanded and cooled, but still containing substantial energy, is applied on a cold reheater line 50 to, a reheater 52 which is also part of boiler 14. The pressure and 45 temperature of the steam in line 44, upstream of main control valve 38 and generally at its inlet 45 are measured by sensors (not shown) to produce a representative first pressure signal P1 and a first temperature signal T1 which are transmitted to data processing subsystem 24. The pressure and temperature of the steam in cold reheater line 50, downstream of high pressure turbine 48 at substantially its exit, are measured by sensors (not shown) to produce a representative third pressure signal P3 and a third temperature signal T3 which are also transmitted to data processing subsystem 24.

A pressure sensor (not shown) produces a pressure signal P2, representing the pressure sensed proximate the first stage of HP turbine 48, and the signal is transmitted to data processing subsystem 24.

An intermediate pressure turbine 54 (hereinafter---IP-turbine) receives reheated steam from 55 reheater 52 on a hot reheiter line 56, expands the steam to extract energy from it and exhausts the steam through an exhaust line 58 to a low pressure turbine 60. Mechanical outputs of HP turbine 48, IP turbine 54 and low pressure turbine 60 (hereinafter "LP" turbine) are nterconnected mechanically as shown by coupling means 62 and 64 which are, in turn, mechanically coupled to connection 32 and to the generator. A fourth temperature T4 and pressure P4 in hot reheater line 56, upstream of IP turbine 54 are measured by sensors (not j;hown) and representative signals are transmitted to data processing subsystem 24. In addition, :a fifth temperature T5 and pressure P5 of the steam in line 58, downstream of [P turbine 54, is measured by sensors (not shown) and signals representing those quantities are also transmitted to data processina subsystem 24. In another embodiment, T5 and P5 are measured at the low 65 GB 2 152591 A pressure bowl of LP turbine 60.

Exhaust steam from LP turbine 60 is applied on a line 66 to a condenser 68 wherein the steam is condensed to water and thereafter conveyed on a line 70 to steam generator 42 for reuse. One of the factors which can degrade system efficiency is deficient operation of condenser 68 which can result in higher than normal back pressure at the exhaust of low pressure turbine 60. Such back pressure is an indication that the operation of condenser 68 requires adjustment for improved efficiency. A pressure sensor (not shown) in line 66 produces an exhaust pressure signal P6 which is transmitted to data processing. subsystem 24 for further processing and display.

It should be noted that the temperature sensors used may be of any convenient type, 10 however, in the preferred embodiment, each temperature sensor includes a plurality of high accuracy chromel constantan (Type E) thermocouples disposed in a well and positioned to give access to the steam whose temperature is to be measured. By using a plurality of thermocouples for each sensor, the results from the plurality of thermocouples may be averaged to substantially reduce individual thermocouple errors or minor differences in system temperatures. In addition, 15 the availability of more than one thermocouple offers a measure of redundancy in case of failure of one or more of the thermocouples at a sensor location. Transmission of the temperature signals may be accomplished using analog voltages or the temperature signals may be digitized before transmission to make the measurements less susceptible to the lengths of cable runs and to noise. Similarly, the pressure sensors may be of any convenient type such as, for example, pressure sensors commercially available under the name Heise Model 71 5T having appropriate pressure, accuracy and environmental temperature ranges.

Referring now to Fig. 3, there is shown the flow chart for the principal elements making up an operator's thermal performance monitor 72 as part of data processing subsystem 24. The flow chart functionally describes the various components in the operator's thermal performance monitor 72. Beginning at the top left hand corner of Fig. 3, temperature and pressure inputs are supplied to monitor 72. All the temperature and pressure inputs are supplied to a temperature and pressure deviation from design calculator 74. Calculator 74 has a data base therein which maintains the design temperature and pressure values for each sensed temperature and pressure signal. Hence, pressure P1, sensed at the inlet of control valve 38, has a corresponding first design pressure value, P1 DES. Similarly, temperatures T1, T3 etc., have corresponding design temperature values T1 DES, T3DES, etc. These design pressure and temperature values are illustrated within the brackets of calculator 74. The steam temperature and pressure design values are established by the turbine-generator manufacturer or are established during the initial commissioning of the turbine-generator unit. The substantially instantaneous temperatures and 35 pressures sensed throughout the turbine-generator system are displayed to the operator by operator display 76. Calculator 74 subtracts the design values from their corresponding instantaneously sensed signals to obtain temperature and pressure deviations from design. The temperature and pressure deviations from designs are supplied to operator display 76.

It is important to note that the operator display 76 is part of operator interface subsystem 26 40 and that the subsystem must present information in a simplified, easily understood fashion to operator 18. As is commonly recognized in the art, operator 18 is responsible for overseeing several other major control systems in the turbine-generator system. Hence, operator display 76 presents very refined information based upon certain operating parameters, i.e., selected temperature and pressures, to the operator.

Central to the data processing of the raw temperature and pressure data, is an economic loss calculator 78. Basically, economic loss cal ' culator 78 has supplied to it several heat rate correction factors, the electrical power output signal W1, and a design heat rate signal H3. As will be described later, loss calculator 78 manipulates this information and presents specific economic loss figures, in a cost per unit time format, which is normally dollars per day, to the 50 operator through operator display 76.

Specifically, an initial temperature heat rate correction factor signal FHR1 is generated by an initial temperature heat rate correction factor calculator 80. Calculator 80 obtains signal T1 and a signal representative of the substantially instantaneous percentage of rated load at which the system is operating. The signal is illustrated herein as -%LOAD---. The percentage of rated load 55 signal is easily computed and is well known in the art. The initial temperature heat rate correction factor, FHR1, is a function of T1 and %LOAD signal. The initial temperature function is a relationship between the deviation of T1 from the design temperature value T1 DES which results in a percentage change in a design heat rate value.

Fig. 4 graphically illustrates the initial temperature correction factor values for an exemplary 60 system. FHR1 is illustrated by the lines extending through the lower left quadrant and into the upper right quadrant. As illustrated therein, the slope of the initial temperature function is affected by the percentage of rated load. The initial temperature correction factor graph, as well as the reheat temperature correction factor graph of Fig. 5, the initial pressure correction factor graph of Fig. 6, and the exhaust pressure correction factor graph of Fig. 7 are based upon 65 6 GB2152591A 6 theoretically calculated data relating to a certain group of steam turbines and verified by testing of actual steam turbines. These graphs are well known in the art. As is well known in the art, the graphs illustrated in Figs. 4, 5, 6 and 7 are supplied by the turbine-generator manufacturers normally at the time the turbine-generator system is sold to the utility company or owners of the 5 system. The graphs illustrated herein relate only generally to a system schmetically shown in Fig. 2. As is well recognized in the art, HP turbine 48 has an associated design

temperature T1 DES at which a design heat rate value should be attained. When T1 deviates from T1 DES, the heat rate changes graphically as illustrated in Fig. 4.

A reheat temperature heat rate correction factor calculator 82, of Fig. 3, provides means for 10 determining a corresponding signal, FHR2, which is a function of T4 and %LOAD. IP turbine 54 should be operated at a specific design temperature, i.e., T4DES, hence, the FHR2 factor is a percentage change in heat rate as displayed graphically by the lesser sloped lines in Fig. 5.

An initial pressure heat rate correction factor, FHR3, calculator 84 is supplied with pressure P1 and the %LOAD signal as illustrated in Fig. 3. The FHR3 signal is a function of P1, %LOAD, 15 and the design pressure value for HP turbine 48, P1 DES. Graphically, the FHR3 correction factor is illustrated in Fig. 6. Basically, HP turbine 48 is designed to operate at a design pressure P1 DES and deviations from that design pressure affect the heat rate. As clearly illustrated in Fig. 3, the FHR1 signal, the FHR2 signal, and the FHR3 signal are supplied to economic loss calculator 78. All the signals are percentage changes in heat rate from design and 20 are related to the deviation from design of certain operating parameters.

Generally, the overall performance of the turbine-generator system is affected by the back pressure or exhaust pressure present at the exit of the last turbine in the system. Hence, LP turbine 60 has a sensor located on line 66 to determine exhaust pressure P6. P6 is supplied to exhaust pressure heat rate correction factor, FHR4, calculator 86 as is an adjusted flow signal AF from an adjusted flow calculator 88. AF signal can be calculated in many ways as is commonly recognized in the art. One method of calculating adjusted flow AF is based upon T1, V1 (the position of steam admission control valve 38), P1, P1 DES, the steam design flow value FL1, and T1 DES. One algorithm to obtain the adjusted flow signal AF is as follows:

AF = FL1 -[(Tl + 460)i/(T1 DES + 460ff 2-P 1 /P1 DES where FL1 is in pounds per hour and T1, T1 DES is in degrees farenheit and AF is in pounds per hour.

The AF signal and the exhaust pressure signal P6 is applied to calculator 86. Fig. 7 graphically illustrates an exemplary function for determining the factor FHR4. The FHR4 factor is a relationship between the deviation of P6 from a design exhaust pressure value P6DES which results in a percentage change in the design heat rate value for the turbine-generator system. As illustrated in Fig. 7, the instantaneous slope of the exhaust pressure affected by the ratio of adjusted flow AF to the design flow value FL1. The ratio provides the percentage of 40 design flow. Signal FHR4 is supplied to economic loss calculator 78.

As is well known in the art, the turbine-generator system has associated with it a design heat rate value at specific a percentage of rated load. The design heat rate value for the turbine generator system is dependent in part upon the turbine being supplied with steam at design temperature T1 DES and design pressure P 1 DES. Hence, when P 1 and T1 deviates from the 45 design values, the design heat rate for the turbine system changes. A design heat rate calculator provides means for determinining the substantially instantaneous design heat rate H3 for the system including the turbine and the electric generator. A design heat rate signal H3 is generated by calculator 90. The control valve signal V1, signal T1 and signal P1 are supplied to calculator 90. The H3 signal is related to a corrected percentage of flow (PCF2) through the 50 turbine system, and by comparing PCF2 to a data base developed by the turbine-generator manufacturer at or after the initial testing at the commissioning of the turbine-generator unit, the design heat rate signal H3 is obtained. PCF2 can be calculated by many well known methods, one of which follows from the equation:

PC F2 = f(V 1)-[(P 1 /VO L(P 1 T1))/P1 DES/VOL(P1 DES,T1 DESffl' 12 where f(V1) is the percent steam flow through the control valve, VOL(P1J1) is the specific volume of the steam at the pressure and temperature P1, T1, and VOL(P1 DES, T1 DES) is the design specific volume of the steam at design pressure and design temperature values. It is well 60 known in the art how to determine percent steam flow through the control valve as a function of V1.

Calculator 78 obtains FHR1 signal, FHR2 signal, FHR3 signal, FHR4 signal, electrical output signal W1, and H3 signal. Calculator 78 has stored within it a cost per unit heat factor CF at which the system operates. In other words, boiler--- 14 outputs heat or thermal energy at a certain 65 7 GB 2 152 591 A 7 cost per unit heat, such as in dollars per million BTU. Generally, calculator 78 includes means for multiplying the several inputs together along with a several conversion constants thereby developing economic loss signals displayable in cost per unit time. A main steam temperature loss signal LOSS1 is developed by multiplying W1, FHR1, H3 and the cost per unit heat factor signal CF, together with a first constant. With respect to the steam turbine system under discussion herein which includes HP turbine 48, IP turbine 54 and LP turbine 60, the main steam temperature loss signal LOSS1 is added to a reheat steam temperature loss signal LOSS2 to obtain a total temperature loss signal LOSS5. As is well recognizedin the art, if the steam turbine system included only one turbine mechanically coupled to an electromagnetic generator, main steam loss signal LOSS 1 would be directly displayed to the operator of that single turbine 10 system.

One algorithm for determining the main steam temperature loss signal LOSS1 is as follows:

LOSS1 =(FHR 1 (T1,% LOAD)/ 1 00)-H3-1 0 -3-W1 -1 06-24-CF-1 0-6 In the above equation, the main steam temperature loss signal LOSS1 is displayable in dollars per day.

The reheat steam temperature loss signal LOSS2 represents the economic loss of operating IP turbine 54 at a temperature and pressure different from the design temperature and pressure.

One algorithm for determining the reheat steam temperature loss signal LOSS2 is as follows: 20 LOSS2 = (FHR2(T4,%LOAD)/1 00)'H3M 0-3-W1.1 06'24TFM 0-6 The economic loss of operating the steam turbine system 30 at a certain pressure is provided by a main steam pressure loss signal LOSS3 which is derived from the equation:

LOSS3 = (F1-1R3(P1,%LOAD)/1 00)'H3-10-3-W1-1 06'24'CF-1 0-6 An exhaust pressure loss signal LOSS4 relates the economic loss of operating the steam turbine system at an exhaust pressure P6, and one equation for determining the exhaust 30 pressure loss signal LOSS4 is as follows:

LOSS4 = (FHR4(P6,AF)/ 1 00)-H3'1 0 -3W1.1 06-24-CF"] 0.

As stated earlier, the total temperature economic loss LOSS5 is the sum of LOSS1 and LOSS2. Total temperature loss LOSS5, main steam pressure loss LOSS3 and exhaust pressure loss LOSS4 are applied to operator display 76. In this manner, operator 18 is presented, in dollars per day, the economic consequences of operating steam turbine system 30 at a controllable temperature and pressure. The exhaust pressure loss indicates that elements downstream of LP turbine 60 are raising the back pressure and thereby affecting the expansion 40 of the steam through the steam turbine system generally. By altering the control valve position V1, and the input into boiler 14, operator 18 can affect the pressure and temperature of the steam supply to steam turbine system 30 to increase the thermal performance and economic performance of the system. Operator display 76 also indicates electrical power output signal W1 and total control valve position V1 in megawatts and percent respectively.

Fig. 8 illustrates the operator's display for the operator thermal performance monitor. The operator's display may be a CRT or other human readable mechanism. The components of the operator's display have been explained hereinabove. As is recognized in the art, the data supplied to the operator's display could be continuously recorded on appropriate means by data stored subsystem 28. Also, as well recognized in the art, the operator's thermal performance 50 monitor may be coupled to an electronic control system which directly controls steam turbine system 30. In this view, the control system would have acceptable ranges of economic loss values. If steam turbine system 30 was not operating within those preestablished ranges, the electronic control system would alter the various controllable parameters to bring steam turbine system 30 within the acceptable ranges of operation. The display, in Fig. 8, of measured temperatures, pressures and their corresponding deviation from design simply highlight selected areas in steam turbine system 30. The display also presents P2, P3, P5 and their related deviations from design.

Data processing subsystem 24, illustrated in Fig. 1, also includes a results engineer thermal performance monitor. Generally, the results engineer's thermal performance monitor calculates 60 the actual efficiency of the HP and IP turbine, the deviation from design heat rate for those turbines, and the power loss associated with the steam turbine system operating at an instantaneous supply temperature, and instantaneous reheat temperature, instantaneous supply pressure and an instantaneous exhaust pressure. Due to the results engineer's extensive technical training, education and turbine-generator system experience, he or she, when 8 GB2152591A 8 presented with this information, can recommend maintenance procedures or substantial changes in the overall operation of the steam turbine system 30, boiler 14, condensor 68, and other related elements in the steam turbine plant. Commonly, the results engineer reviews the turbine system performance over a substantially long period of time, such as one week, as compared to the shift operator's supervision of the turbine system operation. Substantially longer periods of time are utilized for long term trend analysis. Fig. 9 illustrates a flow chart showing the functional aspects of a portion of the results engineer's thermal performance monitor which is included in data processing subsystem 24. Primarily, Fig. 9 deals with means for calculating the enthalpy of the steam entering and leaving the HP turbine and [P turbine, converting those enthalpy values to efficiency values for the HP and IP turbine, and subsequently calculating the HP nand IP deviation in heat rate from design. An input enthalpy calculator 110 obtains temperature T1 and pressure P 1 at the inlet of control valve 38. Calculator 110 may include a data base which can be characterized by a Mollier diagram. Hence, the input enthalpy J1, of the steam is calculated and a signal is applied to an actual HP efficiency calculator 112. An output enthalpy calculator 114 is supplied with T3 and P3, determines the output enthalpy J1. of the steam, and thereafter applies signal J l,. to calculator 112. The signal J 1, and signal J 1. are calculated on a substantially instantaneous basis with the sensing of the temperatures and pressures. Hence, calculator 112 is continually updating the efficiency signal representative of the operating condition of HP turbine 48. An isentropic output enthalpy calculator 116 receives T1, P1 and P3. The isentropic enthalpy 20 drop J l., is based upon the instantaneous temperature and pressure readings and assumes an adiabatic and reversable process in the steam turbine and the control valve. This calculation is well known in the art and may be obtained from a data base characterized by as a Mollier diagram. 25 Calculator 112 obtains the ratio between the actual enthalpy drop (J 1,-J 1J and the isentropic 25 enthalpy drop (J 1,- J 1,,) and generates E3 signal. That actual H P efficiency signal E3 is supplied to a results engineer's display 116 which is part of the results engineer interface subsystem 27 illustrated in Fig. 1. The efficiency of IP turbine 54 is also of concern to the results engineer. Hence, calculator 30 118 receives signal T4 and signal P4 sensed at the inlet of 1 P turbine 54 and determines the input enthalpy J2i for that turbine. Calculator 120 receives signal T5 and signal P5, representing the condition of the steam exiting W turbine 54, and determines the output enthalpy signal J2.. Calculator 122 receives signal T4, signal P4 and signal P5 to determine the isentropic output enthalpy J2., for IP turbine 54. These three enthalpy signals are applied to an actual IP efficiency calculator 124. Calculator 124 subtracts output enthalpy signal J2e from input enthalpy signal J2, as well as subtracts the isentropic enthalpy signal J2, from input enthalpy signal J2, A ratio of the actual enthalpy drop and isentropic enthaipy drop for IP turbine 54 produces the actual IP efficiency signal E4. E4 is ultimately supplied to results engineer's display 116.

A design efficiency calculator 126 obtains signal T1, signal P1 and control valve position signal V1 to determine the substantially instantaneous design efficiency of the steam turbine.

The design efficiency signal E1 is based upon the above inputs and the design pressure and temperature values for the steam turbine. Specifically, calculator 126 includes therein a data base formulated bv the turbine-nenerator manufacturer or established during the initial commis- sioning of the turbine-generator unit. Siqnal E 1 is based upon the corrected percentage of steam flow, PC172, through the turbine system. One of the methods of determining PCF2 is disclosed by the algorithm discussed above in relationship to design heat rate calculator 90 and utilizes V1, P1 and T1 as inputs.

Signal Ell is supplied to HP deviation in heat rate from design calculator 130 as is actual HP efficiency signal E3. Calculator 130 provides means for obtaining the deviation heat rate from 50 design.. H1, by subtracting the instantaneous design HP efficiency E1 from the actual efficiency E3 and dividing the resultant by the instantaneous design efficiency E1 and a conversion factor. The algorithm for the HP deviation in heat rate signal H 'I is as follows:

H 1 = - (1 OC(E3 - El)/l))/6.7 The H 1 signal is applied to result engineer's display 116. The divisor 6. 7 depends upon the specific turbine design, and hence is exemplary only.

A design efficiency for the IP turbine 132 is supplied by the turbine manufacturer as an installation dependent constant E2. It is well known in the art that the IP turbine's design 60 efficiency is substantially constant due to the absence of valves or other devices obstructing the flow of steam therethrough. A person of ordinary skill in the art recognizes that the IP design efficiency is constant over the substantially entire range of steam flow. Design efficiency signal E2 is supplied to an IP deviation in heat rate from design calculator 134. Also supplied to calculator 134 is actual [P efficiencv signal E4. Calculator 134 subtracts signal E2 from signal 65 9 GB2152591A 9 E4, divides the resultant by signal E2 and multiplies by a conversion factor to generate the IP deviation in heat rate from design signal H2. One algorithm for H2 follows:

H2 (1 00-((E4 - E2)/E2))/1 0) 5 Signal H2 is supplied to results engineer's display 116 as is signal E2 and signal E4. The factor is exemplary only and relates to a specific turbine system. As illustrated in Fig. 9, both the HP deviation from design signal H1 and W deviation from design signal H2 are transmitted to other elements functionally shown in Fig. 10.

Fig. 10 is a flow chart illustrating the remaining porflon of the results engineer's thermal 10 performance monitor. Basically, Fig. 10 relates to the power losses associated with operating the steam turbine system 30 at controllable temperatures and pressures which may differ from design values.

An initial temperature kilowatt load correction factor (FLOAD 1) calculator 140 is supplied with T1 and the percentage of rated load signal %LOAD. The function for determining factor FLOAD1 is an expression based upon the deviation of temperature T1 from the design temperature T1 DES which results in a percentage change in the design heat rate value for the turbine system. The slope of this initial temperature power expression is affected by %LOAD signal. One FLOAD1 function is graphically illustrated in Fig. 4 by the lines extending from the upper left quadrant to the lower right quadrant. In a similar fashion to the initial temperature heat rate correction factor function, FHR1, described in relationship to calculator 80 of Fig. 3, the function is based on theoretical calculations which are confirmed by field tests on actual turbine systems.

The signal FLOAD1 is applied to a main steam temperature power loss, W6, calculator 142.

Calculator 142 is supplied with the electrical power output signal W1 and one method of 25 calculating W6 is as follows:

W6 = (FLOAD 1 (T1,% LOAD)/ 1 00)W Signal W6 may be directly applied to results engineer's display 11 6b or may be supplied to 30 summer 144 as illustrated in Fig. 10.

A reheat temperature kilowatt load correction (FLOAD2) factor calculator 146 is supplied with T4 and %LOAD. The function for determining the FLOAD2 factor is an expression based upon the deviation of temperature T4 from a reheat design temperature value T4DES which results in a percentage change in the design heat rate value for the turbine system. The FLOAD2 function 35 is graphically illustrated in Fig. 5 and is generated substantially similar to FHR2, FLOAD1 and FHR1.

The FLOAD2 signal is supplied to a reheat steam temperature power loss, W7, calculator 148 as is signal W1. Calculator 148 divides the FLOAD2 factor by a correction factor and multiplies by signal W1 as follows in one exemplary algorithm:

W7 = (FLOAD2(T4, %LOAD)/ 1 00)W1 Signal W7 is supplied to summer 144 wherein that signal is added to signal W6 to provide a total temperature power loss signal W9. Signal W9 is ultimately presented to results engineer's 45 display 11 6b.

An initial pressure kilowatt load correction factor (FLOAD3) calculator 150 obtains P1 and %LOAD. The function for determining the signal FLOAD3 is an expression based upon the deviation of signal P1 from P1 DES which results in a percentage change in the design heat rate value for the steam turbine system. In a similar fashion to the initial pressure heat rate correction factor FHR3, the FLOAD3 factor has a slope which is affected by the percentage of rated load signal. One example of the initial pressure correction factor as it relates to changes in kilowatt load is graphically illustrated in Fig. 6. It is to be recognized that the FLOAD1 factor, the FLOAD2 factor and the FLOAD3 factor functions are established in the same manner as the corresponding heat rate correction factors discussed earlier.

The FLOAD3 signal is applied to a main steam pressure power loss, W8, calculator 152 as is signal W1. Calculator 152 provides means for determining signal W8 by dividing FLOAD3 signal by a conversion factor and multiplying by signal W1 as follows:

W8= - (FLOAD3(P 1,% LOAD)/ 1 00)-W1 Signal W8 is applied to display 11 6b.

A poor exhaust pressure power loss signal W3 indicates to the results engineer a power loss based upon unduly high turbine exhaust pressure due to elements in the system downstream of LP turbine 60. Signal W3 is generated by an exhaust pressure power loss calculator 154 which65 GB 2 152591A 10 receives signal W1 and the exhaust pressure heat rate correction factor signal FHR4. The exhaust pressure heat rate correction factor signal FHR4 is generated by an appropriate calculator 156. Calculator 156 and an adjusted flow, AF, calculator 158 are substantially similar to calculator 86 and calculator 88 of Fig. 3. It should be appreciated that the results engineer's thermal performance monitor may be independent from the operator's thermal performance monitor or may be combined with the operator's monitor. In the latter situation, duplication of calculator 158 and 156 would be unnecessary. One algorithm to obtain W3 is as follows:

W3 = [FHR4(P6,AF)/(1 00 + FHR4(P6AFffi-M An HP and IP turbine efficiency power loss calculator 160 receives the HP deviation in heat rate from design signal H1 and the IP deviation in heat rate from design signal H2 as illustrated in Fig. 10. Signal W 1 is also supplied to calculator 160. An H P and 1 P turbine eff iciency power loss signal W2 is calculated by multiplying signal H 'I by a conversion factor, adding to the resultant signal H2 and by multiplying the resulting sum by signal W1 and another conversion factor. One equation for deriving the HP and W efficiency power loss signal W2 is as follows:

W2 = ((1.7-Hl) + H2)'(W1 /100) Signal W2 is supplied to display 11 6b. The 1.7 conversion factor in the above equation is related to the specific turbine system. That factor illustrates that the HP deviation in heat rate from design contributes more to a power loss than the IP deviation in heat rate from design. This greater effect is noted because smaller enthalpies within the HP turbine, as reflected in H 1, reduce the enthalpy which can be added to the steam in the reheater. Hence, the energy which can be extracted from the steam by the W turbine is reduced.

Design temperature and pressure data base 162 supplies the design pressure and tempera tures to the result engineer's display 11 6b. Also supplied to the results engineer's display 11 6b are all the sensed pressures and temperatures P1, P2, P3, P4, P5, P6 and T1, T3, T4 and T5.

The origin of these sensed signals are clearly shown in Fig. 2.

Fig. 11 generally illustrates a result engineer's display which presents the control valve 30 position V1, the design efficiencies E1 and E2, the actual efficiencies E3 and E4, the deviation in heat rate from design H 'I and H2, as well as the various power loss signals W9, W8, W2 and W3 and their relationship to the measured load or the electrical power output signal W1.

A person of ordinary skill in the art recognizes that the turbinegenerator systern can be operated beyond its recommended design parameters, i.e., T1 and P1 can be higher than 35 T1 DES and P1 DES. Carrying this point further, the system can be operated at higher efficiencies which result in negative economic losses (as in the operator's monitor) and in negative power losses (as in the results engineer's monitor). The monitor(s) discussed and claimed herein are meant to cover such a situation.

It is to be recognized that the operator's thermal performance monitor and the results 40 engineer's thermal performance monitor may be combined into one general thermal perform ance monitor. One of ordinary skill in the art would recognize the feasibility of such a combination. The claims appended hereto are meant to cover such a general thermal performance monitor.

Throughout the discussion of the embodiment of the present invention, steam turbine system 45 included HP turbine 48, IP turbine 54, and LP turbine 60. One of ordinary skill in the art would recognize that other steam turbine systems could utilize the turbine thermal performance monitor as disclosed herein. In fact, a single steam turbine could be driving an electromagnetic generator and the thermal performance monitor could operate in conjunction with that single steam turbine. For clarity the foregoing discussion only focused on a three turbine system.

However, some of the claims appended hereto relate to a single turbine system. To differentiate between the various signals in either system, lower case letters identify signals in the single turbine system and upper case letters identify signals in the multiple turbine system. For example, in the single turbine system, the first temperature is designated '11---and the first substantially instantaneous design efficiency is designated---el -. In contrast, the corresponding signals in the multiple turGine system are designated '11---and---E2- respectively. This nomenclature is used for clarity and is not meant to be limiting in any sense.

From another perspective, a turbine system may include two or more high pressure steam turbines mechanically coupled to an intermediate pressure turbine and a low pressure turbine and ultimately coupled to a lectric generator. One of ordinary skill in the art could utilize the 60 present invention by adding appropriate means to include this additional turbine's performance into the thermal performance monitor. The claims appended hereto are meant to cover such a geam turbine system.

1 Although several sensors are discussed to obtain PJ signals herein, it should be recognized lpat conditioning means or other fail-safe means could be utilized with the sensors to insure the 65 1 11 GB 2 152591 A 11 integrity of the inputs into the thermal performance monitor. These conditioning means could be adjusted periodically, such as annually, to correct the raw PJ data.

One of ordinary skill in the art will recognize that many types of electrical devices could be utilized as a thermal performance monitor disclosed herein. In one embodiment, a Hewlett Packard HP 1000 minicomputer associated with a set of Fortran subroutines were utilized. In a second embodiment, an Intel 8086 minicomputer, manufactured by Intel Corporation, was utilized with the Fortran subroutines. However, it is to be understood that even though several working embodiments utilized digital electronic equipment, the operatlion of a completely analog thermal performance monitoring device could be developed by one of ordinary skill in the art as 10 disclosed herein.

The claims appended hereto are meant to cover all modifications apparent to those individuals of ordinary skill in the art. The recognition of various constants, proportional ities, numbers and conversion factors stated in the claims is not meant to be limiting.

Claims

1. For or in combination with a steam turbine driving an electric generator and a steam generator controllably supplying steam through a control valve to said turbine at a controllably selected pressure and temperature, said steam turbine operating at a known cost per unit heat factor [ef] and said turbine having a first design temperature [tl des], pressure [p 1 des] and steam flow [fil] values; a thermal performance monitor providing information to the operators 20 and results engineer of said turbine on a substantially continuous basis comprising:

means for sensing the substantially instantaneous first pressure [p l] and first temperature [tl] of said steam upstream of said control valve and providing representative pressure and temperature signals; means for sensing the substantially instantaneous position of said control valve [vl] and 25 providing a representative valve position signal; means for sensing the substantially instantaneous first exhaust pressure [p3] of said steam downstream of said turbine and providing a representative first exhaust pressure signal; means for sensing the substantially instantaneous electrical power output [wl] from said electric generator and providing a representative power signal; means for determining the percentage of rated load [%load] at which said turbine is instantaneously operating at and providing a representative signal; means for determining a first initial temperature heat rate correction factor [fhrl], which is a function of said first temperature signal [tl] and the percentage of rated load signal [%load], and providing a first temperature heat rate correction signal; means for determining a first initial pressure heat rate correction factor [fhr31, which is a function of said first pressure signal [pl] and said percentage of rated load signal [%load], and providing a first pressure heat rate correction signal; means for determining a first exhaust pressure heat rate correction factor [fhr41, which is a function of said first exhaust pressure signal [p3], said first temperature signal [tl], said first 40 design temperature value [tl des], said valve signal [vl], and the first design steam flow value [fil], and providing a first exhaust pressure heat rate correction signal; means for determining a substantially instantaneous first design heat rate [h3] for said turbine and said electric generator and providing a signal, said substantially instantaneous first design heat rate [h3] being related to said first temperature [tl] and first pressure [pl] signals, said valve signal [vl] and said first design pressure [p 1 des] and first design temperature [tl des] values for said turbine; means for multiplying said power signal [wl], said first temperature heat rate correction signal [fhrl], said design heat rate signal [h3] and a signal representative of said cost per unit heat factor signal [cf] together with a first constant to provide a first main steam temperature loss 50 signal [lossl] displayable in cost per unit time; means for multiplying said power signal [wl], said first initial pressure heat rate correction signal [fhr3], said first design heat rate signal [h3] and the cost per unit heat factor signal [cf] together with a second constant to provide a first steam pressure loss signal [loss3] displayable in cost per unit time; means for multiplying said power signal [wl], said first exhaust pressure heat rate correction signal [fhr4], said design heat rate signal [h3] and said cost per unit heat factor signal [cf] together with a third constant to provide a first exhaust pressure loss signal [loss4] displayable in cost per unit time; and means for displaying on a substantially continuous basis said first main steam temperature 60 loss signal [lossl], said first steam pressure loss signal [loss3] and said first exhaust pressure loss signal [loss4], all in said cost per unit time format to inform said operators of the economic consequences of operating said turbine at said controllably selected temperature and pressure and to inform said operators of the economic consequences of operating the elements in the balance of said turbine system downstream of said turbine.

12 GB

2 152591A 12 2. A combination as in claim 1 wherein said first temperature [tl] and first pressure [pl] are sensed at the inlet of said control valve, said thermal performance monitor further including:

means for measuring a substantially instantaneous outlet temperature [t3] and said exhaust pressure [p3] being a substantially instantaneous outlet pressure; means based on said instantaneous first temperature [tl] and pressure [pl] said outlet 5 temperature [t3] and pressure [p3] for calculating a first actual enthalpy drop [deltaJ] in said steam turbine and said control valve; means for calculating a first isentropic enthalpy drop [delthJ,,,,] in said steam turbine and said control valve based on said first temperature [tl] and said first pressure [pl 1 and said outlet pressure [p3] assuming an adiabatic and reversible process in said steam turbine and said 10 control valve; means for determining a substantially instantaneous first design efficiency [e 1] of said steam turine based upon said first temperature [tl] and pressure [pl], said control valve position [vl] and said first design pressure [p 1 des] and temperature [t 1 des] values for said steam turbine; means for calculating a first actual efficiency [e3] for said steam turbine based upon the ratio 15 between said first actual enthalpy drop [deltaJ] and said first isentropic enthalpy drop [de'tajlhl; means for calculating a first deviation in heat rate from design [h 1] for said steam turbine by subtracting said instantaneous first design efficiency [el] from said first actual efficiency [e3], dividing by said first design efficiency [el] and multiplying by a first proportionality; and means for presenting said instantaneous first design efficiency [el], said first actual efficiency 20 [e3] and said first deviation in heat rate [hl].

3. The combination as in claim 2 further including:

means for determining a first initial temperature kilowatt load correction factor [fload 11 based upon said first temperature [tl] and said percentage of rated load [%load]; means for calculating a first main steam temperature power loss [w6] by multiplying said first 25 initial temperature kilowatt load correction factor [fload 1] by said instantaneous electrical power output [wl] and multiplying by a second proportionality; means for determining a first initial pressure kilowatt load correction factor [fload3] based upon said first pressure [pl] and said percentage of rated load [%load]; means for calculating a first main steam pressure power loss [w8] by multiplying said first 30 initial pressure kilowatt load correction factor [fload3] by said instantaneous electrical power output [wl] and multiplying by a third proportionality; means for calculating a first deviation from design efficiency power loss [w21 by multiplying said first deviation in heat rate from design [M] by said instantaneous electrical power output [wl] and by a fourth proportionality; means for calculating a first exhaust pressure power loss [w3] by dividing said first exhaust pressure heat rate correction factor [fhr4] by the sum of a first number and said first exhaust pressure heat rate correction factor [fhr4] and multiplying the resultant by said electrical power output [wl]; and said means for presenting also displays said first main steam temperature power loss [w6], 40 said first main steam pressure power loss [w8], said first deviation from design efficiency power loss [w2], said first exhaust pressure power loss [w3].

4. In or for combination with at least a first, a second, and a third steam turbine driving an electric generator and a steam generator as a steam turbine-generator system, said steam generator controllably supplying steam through a control valve to said first turbine at a controllably selected temperature and pressure, said steam exiting said first turbine and flowing through a reheating means then into said second turbine and subsequently flowing to said third turbine, said turbine-generator system operating a a known cost per unit heat factor [CF], said turbine-generator system having a first design temperature [T1 DES), pressure [P1 DES] and steam flow [FL11 values; an operator's thermal performance monitor providing information to the operators of said turbine-generator system on a substantially continuous basis comprising:

means for sensing a substantially instantaneous first pressure [P1] and first temperature [T1] of said steam upstream of said control valve and providing representative pressure and temperature signals; means for sensing a substantially instantaneous position of said control valve [V1] and 55 providing a representative valve position signal; means for sensing a substantially instantaneous fourth temperature [T4] of the steam upstream of said second turbine but downstream of said reheating means and providing a representative fourth temperature signal; means for sensing a substantially instantaneous exhaust pressure [P6] of said steam downstream of said third turbine and providing a representative exhaust pressure signal; means for sensing a substantially instantaneous electrical power output [Wl] from said electric generator and providing a representative signal; means for determining a percentage of rated load [%LOAD] at which said turbine is instantaneously operating at and providing a representative signal; 13 GB 2 152591 A 13 means for determining an initial temperature heat rate correction factor [FH R 1], which is a function of said first temperature signal [T11 and the percentage of rated load signal [%LOAD], and providing an initial temperature heat rate correction signal; means for determining a reheat temperature heat rate correction factor [FHR2], which is a function of said fourth temperature signal [T4] and said percentage of rated load [%LOAD] 5 signal, and providing a reheat temperature heat rate correction signal; means for determining an initial pressure heat rate correction factor [FHR3], which is a function of said first pressure signal [P1] and said percentage of rated'load signal [%LOAD], and providing an initial pressure heat rate correction signal; means for determining an exhaust pressure heat rate correction factor [FHR4], which is a 10 function of said exhaust pressure signal [P61, said first temperature signal [T1], said first design temperature value [T1 DES], said valve signal [V1], and said design steam flow value [FL1], and providing an exhaust pressure heat rate correction signal; means for determining a substantially instantaneous design heat rate [H3] for said turbine- generator system and providing a design heat rate signal, said substantially instantaneous design heat rate [H31 being related to said first temperature [T1] and pressure [P1] signals, said valve signal [V1] and said first design pressure [P1 DES] and temperature [T1 DES] values for said turbine-generator system; means for multiplying said power signal [W1], said first temperature heat rate correction signal [FHR1], said design heat rate signal [H3] and a signal representative of said cost per unit 20 heal factor signal [CF] together with a first constant to provide a main steam temperature loss signal [LOSS1] displayable in cost per unit time; means for multiplying said power signal [W1], the reheat temperature heat rate correction signal [FHR2], said design heat rate signal [H3] and said cost per unit heat factor signal [CF] together with a second constant to provide a reheat steam temperature loss signal [LOSS2] 25 displayable in cost per unit time; means for multiplying said power signal [W1], said first pressure heat rate correction signal [FHR3], said design heat rate signal [H3] and the cost per unit heat factor signal [CF] together with a third constant to provide a steam pressure loss signal [LOSS3] displayable in cost per unit time; means for multiplying said power signal [W1], said exhaust pressure heat rate correction signal [FHR4], said design heat rate signal [H3] and said cost per unit heat factor signal [CF] together with a fourth constant to provide an exhaust pressure loss signal [LOSS4] displayable in cost per unit time; means for summing said main steam temperature loss signal [LOSS 1] and said reheat steam 35 temperature loss signal [LOSS2] to provide a total steam temperature loss signal [LOSS5]; and means for displaying on a substantially continuous basis said total steam temperature loss signal [LOSS5], said steam pressure loss signal [LOSS3] and said exhaust pressure loss signal [LOSS4], to inform said operators of the economic consequences of operating said turbine- generator system at said controllably selected temperature and pressure and to inform said operators of the economic consequences of operating the elements in the balance of said turbine-generator system downstream of said third turbine.

5. A combination as in claim 4 wherein said turbine-generator system having a design heat rate value established at said first design pressure [P1 DES] and said first design temperature [T1 DES], a reheat design temperature value [T4DES] and an exhaust design pressure value [P6DES]; wherein the function for determining said initial temperature heat rate correction factor [FH R 'I l is based upon the deviation of said first temperature [T1] from said first design temperature value [T1 DES] which results in a percentage change in said design heat rate value, and the slope of the initial temperature function being affected by said percentage of rated load [%LOAD]; the function for determining said reheat temperature heat rate correction factor [FHR2] is based upon the deviation of said fourth temperature [T4] from said reheat design temperature value [T4DES] which results in a percentage change in said design heat rate value, and the slope of the reheat temperature function being affected by said percentage of rated load [% LOAD]; the function for determining said initial pressure heat rate correction factor [FHR31 is based upon the deviation of said first pressure [P1] from said first design pressure value [P1 DES] which results in a percentage change in said design heat rate value, and the slope of the initial pressure function being affected by said percentage of rated load [%LOAD]; and The function for determining said exhaust pressure heat rate correction factor [FHR4] is based 60 upon the deviation of said exhaust pressure [P6] from said design exhaust pressure value [P6DES] which results in a percentage change in said design heat rate value, and the instantaneous slope of the exhaust pressure function being affected by the adjusted steam flow value [AF] through said first turbine, said adjusted steam flow value [AF] being calculated from said first temperature signal [T1], said first design temperature value [T1 DES], first pressure GB 2 152 591 A 14 signal [P 1], first design pressure va I ue [P 'I DES], said design steam flow va l ue [FL1], and said valve position signal [V1].

6. In or for combination with a first, second and third turbine driving an electric generator and a steam generator controllably supplying steam through a control valve to said first turbine at a controllably selected pressure and temperature, said steam turbine having a first design temperature IT1 DES], pressure [P1 DES] and steam flow [FL1] values, and said second turbine having an installation dependent design efficiency constant [E2]; a results engineer's thermal performance monitor providing information to the results engineer of the turbine-generator system on a substantially continuous basis comprising:

means for measuring the substantially instantaneous position of said control valve [V1 j; 10 means for measuring a substantially instantaneous first temperature [T1] and a first pressure [P 1] at an inlet of said control valve; means for measuring a substantially instantaneous third temperature [T3] and a third pressure [P3] at an outlet of said first turbine; means for measuring a substantially instantaneous fourth temperature [T4] and pressure [P4] 15 at the inlet of said second turbine:

means for measuring a substantially instantaneous fifth temperature [T5] and pressure [P5] between the outlet of said second turbine and the inlet of said third turbine; means for measuring a substantially instantaneous exhaust pressure [P6] at the outlet of said third turbine; means based on said instantaneous first and third temperatures and pressures [T1, P1, T3, P3] for calculating an actual enthalpy drop in said first turbine and said control valve [deltaJl]; means for calculating an isentropic enthalpy drop [deltaJ 1,j in said first turbine and said control valve based on said instantaneous first temperature [T1], said instantaneous first pressure [P1] and said third pressure [P3] assuming an adiabatic and reversible process in said 25 first turbine and said control valve; means for determining a substantially instantaneous design efficiency [E1] for said first turbine based upon said first temperature [T1] and pressure [P 1], said control valve position [V1] and said first design pressure [P1 DES] and temperature [T1 DES] values; means for calculating the actual efficiency of said first turbine [E3] based upon the ratio between said actual enthalpy drop [deltaJl] and said isentropic enthalpy drop [deltaJ1.,j of said first turbine; means for calculating the deviation in heat rate from design [H 1] for said first turbine by subtracting said instantaneous design efficiency [E1] from said actual efficiency [E3] for said first turbine and dividing by said design efficiency [E1] for said first turbine and multiplied by a 35 first conversion factor; means based on said fourth and fifth temperatures and pressures [T4, P4, T5, P5] for calculating an actual enthalpy drop for said second turbine [deltaJ2]; means for calculating an isentropic enthalpy drop for said second turbine [deltaJ2,j based upon said fourth temperature and said fourth pressure and said fifth pressure [T4, P4, P5] assuming an adiabatic and reversible process in said second turbine; means for calculating the actual efficiency of said second turbine [E4] based upon the ratio between said actual enthalpy drop for said second turbine [deltaJ2] and said isentropic enthalpy drop for said second turbine [deltaJ2.1h]; means for calculating the deviation of heat rate from design for said second turbine [H2] by 45 subtracting said design efficiency constant for said second turbine [E2] from said actual efficiency of said second turbine [E4] and dividing by said design efficiency constant of said second turbine [E2] and multiplying by a second conversion factor; means for measuring the substantially instantaneous electric power output [Wl] from said electric generator; means for calculating a deviation from design power loss 1W2] by multiplying said deviation in heat rate from design for said first turbine [H 1] by a third conversion factor adding to the resultant said deviation heat rate from design for said second turbine [H2], and by multiplying the resulting sum by said electric power output [Wl] and a fourth conversion factor; means for determining the percentage of rated load [%LOAD] at which said steam turbine is 55 instantaneously operating bt; means for determining an initial temperature kilowatt load correction factor EFLOAD1] based upon said first temperature [T1] and said percentage of rated load [%LOAD]; means for calculating a main steam temperature power loss [W6] by multiplying said initial temperature kilowatt load correction factor [FLOAD1] by said instantaneous electrical power 60 output 1W11 and dividing by a fifth conversion factor; means for determining a reheat temperature kilowatt load correction factor [FLOAD2] based upon said fourth temperature [T4] and said percentage of rated load [%LOAD]; means for calculating a reheat steam temperature power loss [W7] by multiplying said reheat 6 5 temperature kilowatt load correction factor [FLOAD2] by said electrical power output [W 1] and 65 GB 2 152591 A 15 dividing by a sixth conversion factor; means for determining an initial pressure kilowatt load correction factor [FLOAD3] based upon said first pressure [P 1] and said percentage of rated load [%LOAD]; means for calculating a main steam pressure power loss [W8] by multiplying said initial pressure kilowatt load correction factor [FLOAD31 by said instantaneous electrical power output 5 [Wl] and dividing by a seventh conversion factor; means for determining a total temperature power loss [W9] by summing said main steam temperature power loss [W6] and said reheat steam temperature poer loss [W7]; means for determining an exhaust pressure heat rate correction factor [FHR4] based upon said exhaust pressure [P6], said first temperature [T1], said first design temperature [T1 DES], 10 said valve position [V1], and said design steam flow value [FL1]; means for calculating an exhaust pressure power loss [W3] by dividing said exhaust pressure heat rate correction factor [FHR4] by the sum of a first number and said exhaust pressure heat rate correction factor [FHR41 and multiplying the resultant by said electrical power output [W1]; and means for presenting said design efficiency for said first turbine [E 11, said design efficiency constant for said second turbine [E2], said actual efficiency of said first turbine [E3], said actual efficiency of said second turbine [E4], said deviation in heat rate from design for said first turbine [H 1] and for said second turbine [H2], said deviation from design efficiency power loss [W2], said exhaust pressure power loss [W3], said main steam pressure power loss [W8] and 20 said total temperature power loss [W9] to said results engineer.

7. A combination as in claim 6 wherein said turbine-generator system having a design heat rate value at said first design temperature and pressure values, [T1 DES, P1 DES], a reheat design temperature value [T4DES] and an exhaust design pressure value [P6DES], wherein said means for determining said initial temperature kilowatt load correction factor [FLOAD13 is based upon a relationship between the deviation of said first temperature [T1] from said design temperature value [T1 DES] which results in a percentage change in said design heat rate value, and the initial temperature relationship having a slope affected by said percentage of rated load [%LOAD]; said means for determining said reheat temperature kilowatt load correction factor [FLOAD2] 30 is based upon a relationship between the deviation of said fourth temperature [T4] from said reheat design temperature value [T4DES] which results in a percentage change in said design heat rate value, and the reheat temperature relationship having a slope affected by said percentage of rated load [%LOAD]; said means for determining said initial pressure kilowatt load correction factor [FLOAD3] is 35 based upon a relationship between the deviation of said first pressure [P1] from said design pressure value [P1 DES] which results in a percentage change in said design heat rate value, and the initial pressure relationship having aslope affected by said percentage of rated load [%LOAD]; and said means for determining said exhaust pressure heat rate correction factor [FHR4] is based 40 upon a relationship between the deviation of said exhaust pressure [P61 from a design exhaust pressure value [P6DES] which results in a percentage change in said design heat rate value, and the exhaust pressure relationship having an instantaneous slope affected by an adjusted steam flow value [AF] through said turbine system, said adjusted flow [AF] being based upon said first temperature [T1], said design temperature value [T1 DES], said design steam flow value [FL1], 45 first pressure [P1], design pressure value [P1 DES], and said valve position [V1].

8. A thermal performance monitor for or in combination with at least one steam turbine substantially as herein described with reference to and as shown in the accompanying drawings.

9. A steam turbine generator system including a thermal performance monitor as claimed in any preceding claim.

Printed in the United Kingdom for Her Majesty's Stationery Office, Dd 8818935, 1985, 4235. Published at The Patent Office. 25 Southampton Buildings, London. WC2A 1 AV, from which copies may be obtained.