Note: Descriptions are shown in the official language in which they were submitted.
~66~
17TU-2967
STEAH TURBINE-GENERATOR THERMAL
PERFOR~NCE MONITOR
The pres~nt lnvent~on relates to ~team turbin~
and, more particularly, to thermal performance
monitors for evaluating the in~tantaneous per~ormance
of steam turbine-generator ~y~tems.
L~rge ~team turbine-generato~ fiystems represent
- major c2pital investment~ for ~he~r owner~ and their
economic benefit to the owners varies with the
thermal ef~iciency with which the steam ~urbines are
opera~d. To highlight the importance of theem~l
~fficient operation, $t is believed that a difference
of one percent in the efficiency of a steam t~rbine
d~ivin~ a one gigawatt electric generator i& worth .
on the order of tens of millions of dollars over the
life of the unlt. Thu~, the owners of a large ~team
turbine-generator are vita}ly ~nterested in
maintaining the operating parameter6 of the sy~tem as
~lo~e as po~ible to the optimum ~et of operating
: parame~er~ a~ de~ign~d for the ~y~tem, a~d/or
developed during operational t~sting following
i~:itial in~:tallation of the sy~tem, since departure
fro~ these parameter~ tend~ to reduce the thermal
: efficiency. ~n additlon, unavoidable degradatlon in
performance over time ca~ occur due to deter~oration
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17TU-2967
of intarnal part~ and other cau~es. ~e~n~ for
d~t~cting the on~et and æeverity of ~uch
deterior~tion 1~ u~eful. ~urth~r~ore~ lt i8
desirable to ~onitor ~he ~urbine or intern~l
problems, e~pecially thc type which nece 6itate rapid
dete~tlon ther~by peraitting tl~ely ~ction to be
taken.
De~p~te ~he il~por~ance o~ maint~ining the
operatlng para~eters at l~vels which max~m~ze therl~al
e~ficlency, in normal pr~otlce, enco~pa~sing th~
mlnute~to-minute control of the controllable
parameters of a large steam turbine, the turbine
~hift operator3 cu~tomarlly maint~in such operating
parameters at values clo~e to optimu~ levels but
still far enough di~ferent from the optimum to
produce subst~ntial efficiency d~viations w~lich
result in cost penalties. Addit~onally, conventional
power station instrumentation does not provide a
class of information which h~s either the accuracy or
the informatlon content to guide an operator in
ad~ustinq and keeping a st~am turbine ~t its best
perfor~ance levels. In f~c~, it iB po~sible, during
the attempt to optimize 8y8tem performance using
moni~oring sy~te~R of the prlor art, for ~he shift
2S operator to make adjustment~ which~ in~tead of
changing ~he operating parameter~ in the direction of
improved efficiency, change tbe op~rat~ng parameters
ln direction~ resulting ln degraded efficiency.
AB part of the $nsta~1Atlon p~ocedure of a steam
turbine-generator sub6y~tem, it i6 customary for the
owners and/or the contractor or turbine manuf~cturer
to conduct very accurate tests to demon6trate or
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17TU-2967
--3~
determine th~ heat rate of the ~ystem. Neat rate is
a mea~ure o therDal efflciency of ~1 ~team
~urbine-ganerator sy~tem de~ined ~ ~he nu~ber of
uni~s of thermal lnput per unit of ~lectric~l power
ou~put. In ~ne convenlent ~yste~ of units~ heat rate
is measur~d in BTU~ per ~ilowat~ hour of power
output. One ~tandard te~t of heat rat~ ls known as
th~ ASME test and is def$ned in ~n hSME publication
ANSI/~SME PTC 6 ~ 1976 ~t~a~ Turbines. A 6implified
ASME test is described in ~ S~E
AcceDtance:~es~ Procedure Por S~eam ~urblnes~
presented ~t the Joint Power Conference, 8eptember
30, 1980, in Phoenix, Arl~ona. A requirement and
characteristic of both o the above test~ is accurate
instru~entation ~or temperatures, pre~ure~ and flows
within a ~team turbine along with the resulting
generator power output to determine accurately the
ener~y content of such condition~ ~nd tbe resulting
power out~ut. The accuracy of measurement i~
sufficiently great that no mea~urement tolerance need
be applied to the results. Such te~ts are costly to
perform. For example, the s~andard ASME test
re~uires a substantial in~tallation of specialized
mea3uring eguip~ent æ~ a ~ubstanti2l cos~ in
conjunction with a great amount of manpower to
admini~er the test. Thu~, economic reality keeps
the admin~stratlon <: f sllch te~ts limited to the
inltial commi~sion~ng of a new ~tear~ -
tu~bin~-g~n~r~tor ~ystes~ ~nd lles~ ~r0qu~ntly~ to the
30 recommi~s~oning s:~f a ~team turbin~-gener~tor system
at a ~ubsequent time ater a refurbishmen~,
~ esides their COfit, AS~lE-type tests have the
addltional drawback ~hat they ~re not ~uitable ~or
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17TU-2367
use in d~y-to-day opera~ion of a ~teiam
turbine-g@nerator 8y5tem. The typ~8 of
instrumentatlon required ~ay not retaln u~eful
accuracy ~ver extended periods. In ~ddi~ion, even if
~uch testing could be condu~ed on a sub~tantially
ccncurrent, in6santaneou~ and da~ly baals, the type
of ~nor~tion ~onvent~onally produced durlng ~uch
~est~, although invalu~ble in the lnltlal engineering
evaluation of the ~y~tem7 18 of a type wh~ch require~
~uch ~ubst~ntial interpret~tlon and calculation to
derive control adjust~ent6 that lt is, ~t bestr of
marginal v~lu~ in ~uiding an operator in ~nipulaeiny
the controls ~hlch are available to him.
Custom~rlly, the ~hlf~ op~r~tor, directly
1i controlling th~ ~ta~m turbine ~ystem, do~ not h~ve
the time, the inclination, nor the ~ophi~tication to
reduce the t~chnical result~ of the ASME type tests
into an understandable format on a ~ub~tan~ially
instantaneou~ ba~ primary functlon is to
monitor the turbine-generator performance as it
relates to other t~rbine-generator B2tS tied into the
electrical tran~mi~ion Isystem~ In thi~ view, a
thermal p~rform~nce monltor must g~ther relatlvely
instan~aneou~ data Prom th~ turbine-generator ~y~tem
and pr~en~ a limit~d ~ount of in~or~ation to the
~hift operator in a v~ry conci~e, quickly ~eadable
and under~tandable format, ~uch th~t the operator ~n
adjust the turbine-gen~rator set to oper~t~ ~ore
efficiently.
In cont~a~t, a re~ults engin~er r~iews the
periodic performance statist~c~ for the
turbine generator set in a more sophi~ticated and
detailed ~anner~ Since the result~ engineer's
17TU-2967
attention is not im~edia~ely focused on the ~team
pressures and temperatures and other parameters
- affecting the turbine, he can leisurely proceed ~ith
a more detailed analysi~ vf the turbine'~ operation.
From the result~ ~ngineer~ perspective, a detailed
presentation at a ~uch higher ~e~hnical level of the
thermal performance of each ~ajor co~ponent in the
steam turbin2-generator ~y~t~m ~a d~eirable. A an
example, ~he de~iled thermal performance data
compiled, 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 Vi8 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 analysi~ would be facilitated by a
sophisticated thermal performance monitor.
ASME-type testing can, however, be relied on
initially to produce reference or a de~i~n data base
from whi~h optimum se~ of operating parameters and
the related heat rates and other parameters
throughout a new stea~ turbine-generator system can
be derived. Once such optimu~ sets of opera~ing data
are established, oper~ting parameters ~uring later
operation of the 6yste~ may be co~pared to i~ for
determining correct operation of the system.
~
Accordingly, it is an object of the invention to
provide an apparatus or guiding op~imum operation of
a steam turbine-generator system,
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17TU-2967
--6--
It ia ~ furth2r vb~ect of the lnvsntion to
provlde an appara~us ~or lnstrumen~$ng a steam
turbine-generator ~y~e~ ~nd for produclng ~ output
which may be u~ed on ~ eub~tantially lnst~ntaneDus
basis to control the contro~la~le par~meters o~ the
steam turbine and obtain lmproved ~y~tem efflciency,
It i~ a till further ob~ect of the invention to
provide an app~ratus for lnstrumenting a steam
turbine~generator ~y~e~ and for producin~ an output
effective for directly in~3r~ing ~n cperator of the
e~onomio consequences of an e~i~ting set o operating
parameterq ~nd for guiding the operator toward
modifying the operating par~meter6 in ~ ~irection
tending to improve the system efficiency.
It i8 an additlorlal ob~ect o thia invention to
provide for means for in~orming the results engineer
of detailed information and analy~i~ regarding each
major component in the ~team flow path of the
turbine-generator system.
It i~ a further object of the inven~ion to
provide an apparatus for in3trumentlng ~ steam
turbine-gerlerator system which i6 ef fective to
monitor and di~play the thermal perfor~ance of each
major component i~ the steam flow path of the
turbine~generator ~y~tem.
~b~
A ste~m turbin~-generator thermal performance
: ~onitor lnclude~ ~ev~ral ~nsor~ or ~a~uring the
pressure and t~mperature of the steam ln ~ steam
turbine generator ~y~tem. The po~ition of th~ ~team
admi~ion co~trol valve is al60 s~nsed~ An
operator'~ thermal performance ~on~to~ obt~in~ the
pressure a~d ~e~perature upstream of the con~rol
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valve and the exh~u~t pr~8 ure of the ~te~m
downEtrea~ of the turbine~ A p~wer output ignal
rom th~ electric generator 1~ obtained and a means
for determining the percentage of rat~d load ~t which
the turbine 1~ instantan~ou~ly operating at 1~ al~o
provided, An initial temperature heat r~te
correction ~actor i~ generated~ in ad~ition to an
iLnitial pres~ure heat rate corre~ion Pactor and an
exhaust pre~ure heat rate correctic~n iEactor. ~eans
10 fs~r determining the sub tantially instantaneous
design heat rate for the turbin~-generator system is
prov$ded which ifi ba~ed upon the temperature and
prefiaure signal~, the.control valve po~ition s~gnal
and the design pressure and te~perature v~lues for
the steam turbine. ~ main ffte~m temperature 1088
signal is generated by multlplying the fir~t
temperature heat rate correction signal, the power
signal, the design heat rate signal t a~d a signal
repre~en~ative of the co~t per unit heat factor of
2~ operating the ~team generator in the
turbine-generator ~y~tem. ~he ~ain steam temperature
loss signal is displayable in cost per unit time to
the turbine operator. A ~team pressure loss ~ignal,
al30 displayahle in cost p~r unit time, is generated
in a simil~r ~ashion utili2ing a pres~ure he~t rate
correction signal and other siqnals. An exhau~t
preS5~re 1oS6 signal is generated by utilizing the
exh~u~t pres~ur~ heat rate ~orroction signal ~nd
~imilar 6ig~al~. ~he oper~tor~s ~on~tor includes
~e~ns for displ~ying, on a ~ubstantislly con~lnuou~
ba ist the ~ain ~team temperature loss ~ignal, the
~team pre~sure 1099 signal and the exhaust pressure
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17TU-2967
loss sign~l, all in cost per unit time format. This
presentation informs the operator~ of the econo~ic
consequances of operating the ~urbine at the
controllably ~elected tempera~ure and pre~sure and at
a certain exhaust pre~sure.
The ~team turbin~-g~n~rator ~y~tem ~ay include a
flr~ econd and ~ third turbln~ and additional
te~np~ra~ure and pres6ure ~ignal6 are generated and
6upplied ~o the monito~. ~ reh~at steam temperature
10 loss sign~l~ displayable in co~t per unit
time, is summed with the first steam temperature loss
signal to provide a total steam t~mperature loss
signal, The displaying means present~ the total
s~eam temperature los~ signal, in the co~t per unit
1~ time format, to the operator of the steam turbine
generator system.
A results engineer's thermal per~ormance monitor
measures the sub6tantially instantaneous temperature
and pressures throug~.out the steam turbine system.
20 An actual 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 pres~ure turbine ~hereinafter the IP
turbine). The substantlally instan~aneous de~i~n
r erf ic, cnC~
~, 25 e_ for the BP turbinc i8 calculated based
upon the f ir~t temperature, f irst pre~sure, and the
control valve position, in addition ~o the ~esign
pressure and temperature values for ~he ~lP turbi~e.
The IP turbine has an in~tallation dependent constant
for its design efficiency, The actual efficiencies
- of the HP and IP turbine are calculated ba~ed upon
the ratio of the ac~ual enthalpy drop6 and the
isentropic enthalpy drops. A pair of
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17TU-2967
deviation ln heat r~te from deslgn calc~ tor~s
generate sppropraate ~lgnals for the ~P and IP
turbine re~pectively. P~ean~ for presentlng the
actual efficiencies of the ~P and IP turbinel the
5 design eiEf ~clencies of ~he HP and IP tur~ine, and the
HP and IP deviation~ in heat rate rom design allows
~he results engineer to identify the overall
performance of the turbine at a particular time.
The results engirleer's thermal performance
10 moni~or may also include ~eans for calculating a main
steam te~perature power loss, a main ste~ pressure
power loss r a reheat steam temperature power loss, a
turbine efficiency power 1088~ and an exhaust
pressure power loss. These power los6 8ign~1~ are
~5 presented to the results ~ngineer and provide a basis
for ~lter~ng the operating param~ters of the ste~m
turbine-generator 8y8tem, effecting the maintenance
of the system or reco~ending modifications of the
system.
2~ ~
The su~ject matter which is regarded as the
invention is particul~rly pointed out and distinctly
claimed in the concluding portion of the
specification. The invent~on, however, together with
2~ further objects and advantages thereof, may be be~t
understood by reference to the ~ollowlng descrip~ion
taken ln connection with the accomp~nying drawings in
wh~ch;
Fig, 1 1~ a si~plified b70ck di~gram of a s~eam
30 turbin~-generator ~ys'cem according to an e~odimerlt
o the inv~nt ion;
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17TU-2967
10-
FigO 2 i~ a simplified schematic d~agram of a
steam turbi~e-generator ~howing Mon~l:or~ng points
employed in the present ~nvention;
Fig. 3 i~ a flow cbart illustratlng the
function~l a8p~ct8 of an op~r~tor~ th~r~al
performance ~oni~or ~ part of the ~ta processing
sub~ystem of Fig. 1~
Figo 4 is an exemplary Init~al Temperature
Correction ~actor Graph;
Fig. S is an exemplary Reheat Temperature
Correction Factor Graph;
Fig. 6 is an exemplary Initial Pres~ure
Correction Factor Graph;
Fig~ 7 is an exemplary E~haust Pres~ure
Correction Factor Graph;
Fig, ~ illu~trate3 an operator'~ display for the
operator's thermal performance monitor;
Fig. 9 i~ a partial flow chart illustrating the
unct~ onal aspects oP the result~ engineer's thermal
performance monitor a~ part of the data proces~ing
sub~ystem of ~lgure 2:
Fig. 10 is the balance of the flow chart ~h~wn
in Fig. g~ which ~urther illu~trates the ~unctional
aspects of a result ~ngine~r's monitorS and
Fig. 11 illustrates a re~ult engineer'~ display
for the thermal perfor~an~e ~onitor.
~
The principal control~ ~vailable to a shif~
: operator vf a ~team turbine-genera~or ~yg~em i~clude
boiler controls which det~rmlne the temperature and
pressure of the main steam and r~hea~ ~eam ~uppl ies
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17TU-2967
and a main steam admi~ion control valve or valves
which d~termin~ the ~ount of ste~m ~d~ltted to the
fir~t or hig~ pre~sure ~ur~lne ~tage~ Pr~ctic~l
guidance to ~n oper~tor of ~uch ~ st~
turbine-gener~tor ~y~tem include~ evaluation~ o~ the
substantially instantaneou operating para~eter~ in a
manr,er which can be ~nte~pret@d easily, qui~kly and
without detailed technical analy~i~ to fscilitate the
manipulation of the~e principal controls.
Referring now to Pig. t, there i~ ~hown,
generally a steam turbine-senerator ~y~tem 10. Steam
turbine-generator ~ystem 10 includes a ~team
turbine-generator 12 receiving a thermal input from a
~team boiler 14. Boller 14 may be of any convenient
1S type, such a~ ooal-fired or oil~fired. Both ~te~n
turbine-generator 12 and boile~ 14 are controlled by
operator inputR represented by a line 1~ from an
operator 18 to produce an electrie power output
represented by a line 2~. A ~et of measur~d
parameter~ ~rom ~team turbine-generator 12 are
applied on a line 22 to a data processing subsystem
24. A~ will be more fully discussed hereinafter, the
types of mea~ured para~eter~ are tho~e whlch can be
obtained with ~ufficient reliability and accuracy
over the long ter~n and whicb can ~e interpr~ted by
datd proce~sing ~ub~y~tem 24 in a ~ashlon which can
guide opera~or 18 in con~rolling ~team
turbine-generator 12 ~nd boiler 14 on a
minute-by-minute ba i~. Th~ outputs of data
proce~sing ~u~ystem 24 are applied to an operator
interface subsyst~m 26 which may be o~ a conven~onal
type uch as, for example, a c~hode ray tube
display, ~ pri~ter or other type~ of analog or
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17TU-2967
-12-
digital d~æplay devic2s. The output from data
proces~ing sub~ystem 24, ~ay also be appli~d to
data ~torage Rubsys~em 28 wherein ~he data may be
stored for ~hort ter~ or long-term purpo~e-q, Data
storage ~ubsy6te~ 28 may be of any conv~nient type
including a printer, however, in the preferred
embodiment, data proce~ing ~ub~ys~e~ 24 includes a
digital proce~sor ~nd data ~torage ~ubsy~tem 2B
preferably includes a digital ~torage device ~uch as,
for ~xample a magnetic or optical di6c or a ~agnetic
tape storage device.
Coupled parallelly with operator interface
subsystem 26 iB a results engineer interface
æub~yæ~em 27. Intersce 27 allow a re~ults engineer
29 to study the output6 of data processing ~ublsy~tem
24 on a more lelsurely ba~is an compared wlth
operator 18. Result6 engineer 29 communicates with
operator 1a to impro~e the long term performance of
turbine-yenerator syætem 10 due in part to the higher
level, sophistic~ted analysis with which the engineer
views the data. The engineer al80 determines the
: maintenance procedures for the ~ystem and subsystem
27 as~iæt6 in the promulgation of thoRe procedures~
Referri~g now to Fig. 2, a ~lmplified ~chematic
diagram o~ ~team turbine-generator 12 i8 ~hown
including only sufficien~ detail to fully di8cloæe
the present ~nvention~ Ste~m turbine-generator 12 is
: conventional except for ~he ~ea~ure~en~ device8
lnstalled therein to ~upport the pre~en~ invention.
Thus, a deta~led de8cr~ption of :~team
turbine-gener~tor 12 i~ o~ltted. In g~n~ral, the
pre~ent invention rel~e~ on ~emperature and pressur~
: measurements at variou~ lo~ations thrGughoNt ~team
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17TU 2967
-13-
turbine-generator ~ystem, including a ~*~surement of
the gene~ated elec~ric~l pow~r output ~nd co~pares
their relationship ~o corresponding ~e~i~n values to
determlne the power lo~ , effic~en~les ~nd h~at
rates throughou~ the ~y~t~ on a sub~tanti~lly
in6tan aneous b~sis.
St~am turbln~-gener~tor 12, of Fi~ur~ 1,
consi~ts of ~ steam turbina 30 coupl~d throu~h ~
mechanl~al connectlon 32, to an electric generator 34
which gener~tes an elect~ic power o~tput. A
tran~ducer ~not ~hown) in ele¢tric generator 34
;.~ produce~ an electr~ c power ou~put signal W1 which iB
appli~d to line ~ or transmi~sion to data
proce~sing subsy~t~m 24. The operator input on line
16 is ~pplied by hydraulic, ~lectrohydraulic, digital
or other well known mean~, to a main control
valve actuator 36 which affects a main control st~am
admission valve 3B ~ illustrated by line 4~. A
valve position ~ignal V1, is generated by appropriate
means and repre~ents the amount by which main con~rol
~lve 38 is opened, and the ~ignal is appli~d to line
for transmission to data proc~sslng ~ub~ystem 24.
It i~ to be understood that valve 38 is
repre6entative o~ a number of st~am admission control
valve co~only a~sociated with a steam turbine.
A steam generator 42, wh~ch i~ part of boiler
14, produces a ~upply 4f hQt prQssurized ~team which
i~ appli~d to main ~ontrol valve 38 on a line ~4.
The ste~m p3~8ing through main con~rol v~lve 3~ iB
applied on a main ~t~am line 46 ~o an i~put of a high
pres~ure turbine 48~ As utili2ed herein, the term
aHP~ refers t~ high pre~sure turbine 48. The ~team
exiting fro~ 8P turbine ~, now parti~lly expanded
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17TU-2967
and cooled~ but s~ill containing ~ubstantial energy,
is applied on a cold rehea~er line 50 to a reheater
52 which is al~o part of boiler 14. The pre~ure and
temperature of the Bteam in line 44 r upstream of
S m~in control valve 38 ~nd generally ~t lt~ inl~ ~re
measured by ~n~ors (not ~hvwn) ~o produce a
repr~sentatlve ~ir~ pr~sure ~ignal P1 And a
first temperature ~ignal ~1 which are tran~mitted to
data pro~e~slng ~b~y~t~m 24. ~he pre~ure ~nd
temperature o~ the steam in cold reheater line 50,
downstream of high pre~sure turbine 48 at
substan~ially its exit, are measured by sensors ~not
~hown) to produce a representative third pressure
signal P3 and a third temperature signal T3 which are
also transmitted to data processing ~ubsy~tem 24.
A pre~sure ~en30r (not 6hown) produces a
pressure signal P2, representing the pres ure sensed
proxi~ate the f irst stage of ~P turbine 48, and ~he
signal is transmitted to data processing sub.system
2~ 2~.
An intermediate pressure turbine 54 (hereinafter
~IP" turbine) receives reheated s~eam from reheater
52 on a hot reheater line 5S, expands the ~team to
ex~ract energy from i~ and exhausSs the steam through
an exh~ust line 58 to a low preR~ure turbint~ 60.
Mechanical output~ of ~P ~urbine ~ P turbine 5
and low pres~ure turbine 60 (hereinafter ~LP"
turbine~ are interconnec~ed mechanically as shown by
coupling means 62 and 64 which are~ in turn,
mechanical~y coupled to connection 32 ~nd to the
genera~o~ A four~h ~emperature T4 and pre sure P4
in hot reheater line 56, upstrea~ of ~P turblne 54
are measured by sensor~ (not ~hown~ and represenative
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17TU-2967
--15--
~ignals are ~ransmit~ed to data proceq~ing subsystem
24. In addition, a fifth temperature T5 ~nd pres~ure
PS of the steam in line 58, downs~ream of IP turbine
54, i~ measured by sen~ors Inot ~hown) and ~ignals
r~presenting ~ho3~ quantitle~ ~re ~l~o ~ransmittecl to
data processing subsy~tem 24. In another
embodimen~, T5 and P5 3re measured at the low
pres R ure bowl of LP turbine 60~
Exhaust ~team from LP turbine 60 i~ ~pplied on a
line 66 to a c3ndenser 6~ wherein ~he s~eam is
condensed to water and thereafter conveyed ~n a line
70 to steam genera~or 42 for reu6e. One of th~
factors which can degrade sy6tem efficiency i5
deficient operatiQn of cond~nser ~B which can result
in higher than normal back pre~s~re at the exhaust o~
low pressure turblne 60. Such back pre~sure is an
indication that the operation of condenser 68
requires ~dju~tment or imp~oved efficiency. A
pressure sensor (not shown) in line 66 produces an
exhaust pres~ure signal P6 which is transmitted to
data processing ~ubRystem ~4 for further processing
and display.
It ~hould be noted that the temperature sensors
used may be of any convenient type, howeYer, in the
25 preferred embodiment, each temperature ~ensor
include~ a plurality of high accur~cy chromel
con~tant~n lType E~ thermocouples di~posed in a weIl
and posltioned to give access to the stea~ whose
temperature i~ to be ~easured. ~y u8in~ a plurali~y
of thermocouple6 for e~ch ~ensor9 the results Prom
the plurality of thermocouples m~y be av~ra~ed to
substan~ially reduce in~ividual thermocouple
: errors or minor diff~rences in syst~m ~emperatures.
~n addition~ ~the av~ilability of ~ore
17TU-2967
-16-
than one thermocouple offers a mea~ure of redundancy
in case of failùre of one or mo~e of ~he
thermocouples at a sensor location. Transmi~ion of
the temper~ture signals may be acco~plished using
analog voltages or the te~perature ~ignal~ ~ay be
digitized before tr~n~mission to m~ke tbe
mea~ure~ent~ lea~ ~us~eptible to th~ lengths o~ cable
runs and to noise. Similarly, ~he pres~ure sensors
m~y be of any convenient type ~uch ~6~ for sx~mple,
10 pressure sensors commercially available under ~he
r~ame Heise Model 71 5T having appropriate pressure,
accuracy and environmental temperature ranges.
Referring now to Fig. 3, there ~s ~hown the
flow chart for the principal elements making up ~t'l
operator's thermal p~rformance monitor 72 as part of
data processing subsystem 24. T~e flow cl~art
functionally describes the various components in t}ie
operator'~ thermal performance monitor 72. ~eginning
at the top left hand corner of ~ig . 3, temperature
and pressure input~ are ~upplled to moni~or 72. All
the temperature and pressure i~puts are s~pplied to a
temperature and pressure deviation fr~m design
calculator 74. Calculator 74 ha~ a data base therein
which maintains the design temperature and pressure
value~ for ~ach sensed temperature ~nd pr~saure
signal. Hence, pressure Pl, ~en~ed at the inlet of
control valve 3~, ba~ a corresp~nding first design
pres~ure v~lue, P1DES. Similarly, temperatures T1,
T3 etc., have corresponding design temperat~re values
T1DES, T3DES, etc. These design pre~sure and
tempera~ure values are illustrated within the
brackets of calculator 74. The ~team temperature and
17TU-2967
-77-
pres~ure de~ign values are establi~hed by the
turbine-generator manufacturer or ~re e~tabllshed
during the ~nl~ial co~issloning of ~he
turblne-generator u~ The ~ub~tan~aally
in~tantaneous te~peratures ~nd presE;ures sen~ed
throu~hout th~ turbine-gen~rator ~y~tem ~r~ played
to the operator by operator di~play 76~
Calculator 74 subtracts the design value6 from their
corresponding instantaneously sensed ~ignals to
obtain temperature and pres~ure deviations from
design. The temperature and pre~ure deviations from
designs ar~ supplled to operator display 76.
It ifi important to note that ~he oper~tor
display 76 i~ part of operator interface subsystem 26
and that the aub~ystem mu~ present information in a
simpli~ied, easily understood fashion to operator 18.
As is commonly recognized in the art/ operator 18 is
responsible ~or over~eeing ~everal other major
control systems in the turbine-generator system.
Hence, operator display 76 presents very refined
information ba~ed upon certain operating parameters,
i.e~ ~elect~d ~mperature and pre~sures, to the
operator.
Central to the dat2 proces~ng of the raw
temperature and pres6ure data, i8 an economic loss
calculator 78. B~sic~lly, economic 1068 calculator
78 has ~upplied ~o it ~everal heat r~te correction
factors, the electricll power output ~gnal Wl, and a
~esign heat rate signal ~3. A~ ~ill be described
later, 108s calculator 78 manipulates thi~
information ~nd presents ~peclflc economle loss
igure~, in a C06t per unlt time fo~at, which i6
:
~2~
17TU-2967
-~8-
normally dollar~ per day, So ~he oper~tor through
operator display 76.
Specific~lly, ~n initial temperature heat rate
correction factor ~ignal F~R1 i~ generated by an
initial t~mper~ture heat r~ e correction factor
calculator BO. Calculator 30 obtains ~ignal T1 and a
~lgn~l r~pr~ent~tlve of th~ eub~S~ntl~lly
in~tantaneou6 percentage of rated load at which the
8yBtem is op~rat1ng. ~he ~ign~ illustrat~d
~0 herein a6 W~LGADn. The percent~ge of rated load
signal is easily computed and i~ well known in the
art. The initial temperature heat rate correction
factor, FHR1, is a funct.ion of T1 and ~LOAD 8ignal.
The initial temperature ~unction i8 a rel~tionship
between the deviation of T1 from the design
temperature value TlDES which result~ in a percentage
change in a design heat rate value.
Fig. 4 graphically illu~trates the initial
temperature correction factor values fvr ~n exemplary
system. F~1 is illustrated by the lin~s extending
through the lower left quadrant and into the upper
right quadran~. As lllu~trsted therein, the ~lope of
the initial temperature function i6 ~f~ected by the
percentage of rated load. The initial temperature
cvrrec~ion fac~or gr~ph, a~ well a~ the reheat
temperature correction factor graph of Fig. 5, the
~nitial pre~sure correction ~actor ~raph of Fig~ 6,
and ~he exhau t pre~sure correcti4n fa~tor graph of
Fig. 7 ~re ba~ed up~n theoretically calculated data
relating ~o a ~ert~in group of ~team turbi~e~ and
verified by testing o~ actual ~team turbine6. These
graphs are well known in tbe art. As 1~ well known
:
" , .
,: , ..
17TU-2967
in the art, the graph~ illu~trated in Figs. 4, 5t 6
and 7 are ~upplied by the turbine=generator
manufacturer~ nor~ally ~t th* ti~e the
turbine-generator ~yste~ i~ sold to the utility
5 co~pany or owners of ~he ~ystem. ~he g~aph6
illu~trated h~rein relate only generally to a ~ystem
~ch~etically ~hown ~n ~ig. 2~
A~ i6 well recognized in the art, ~P turbine 48
has an associa~ed design temperature T1~ES at which a
design heat rate value should be attai~ed. When T1
deviates from T1DES, the h~at rate change~
graphically as illu~trated in Fig. 4.
A reheat temperature heat rate correctiQn fact~r
calculator 82, of Fig. 3, provides means for
determining a corresponding ~ignal, F~R2, which is a
function of T4 and ~LOAD~ IP turbine 54 should be
operated at a ~pecific design te~perature, i.e.,
T4D~S, hence, the FHR2 fa~tor i~ a percentage change
in heat rate as displayed graphically by the lesser
sloped lines in Fig. 5.
An initiAl preRsure he~t rate correction f~ctor,
FHR3, calculator 84 i8 ~upplied with pres~ure P1 and
the %LOAD ~ignal as illustrated in Fig. 3. ~he FHR3
aignal is a function of P1, ~LO~ and the d~ign
pre~ure value ~or HP turbine 48, PlD~S.
Graphically, the ~HR3 correction factor i~
illu~rated in F.ig. 6. Basical~y, ~P turbine 4~ is
das~gn~d to operate at ~ de~ign pre~sur~ P1~ES a~d
deviation~ ~ro~ that design pres~ure affect the heat
rate. As clearly illu~trated in Fig. 3, the ~HR1
~ignal, tha F~R2 signal, and the F~R3 s~gnal are
suRplied to economic loss calcula~or 78. All the
signal6 are percentage changes in heat r~te
,.
66~7
17TU-2967
_~Q ;~
from design and are related to lthe deviation from
design o certain oper~ting paramets~r3.
Generally, the overall perfor~ance of the
turbin~-gener~tor 8yf3te~m iB affe~ted by the b~ck
S pressure or exhau~t pre~ure pre~enlt st the exit of
the la t turbine in the ~ystem. Hellce, LP turbine 60
has a sensor located on line 66 to determine exhau
pressure P6. P6 i6 ~upplied to exhau~t pre6sure hea~
rate correction faol:or, ~R~, calculator ~6 as is an
t0 adjusted flow ~igrlal AF from an adjusted flow
calculator 88. AF ~ignal can be calculated in many
ways as is commonly reoognized in the art. One
method of calculatlng adjusted flow AF i8 based upon
T1, Vl (the po~ition of steam admis~ion control valve
15 38), Pl, PlDES, the steam design flow value FLl, and
T1~ES. One algorithm 'co ob~ain the ad~u6~ed flow
ignal AP i~ as follows:
. ~ A~ z FLl~ l~Tl + 46a)/(TlDES ~ 460)1 1/2*P1/P1DES
where FL1 is in poun~s per hour and T1, T1DES is in
l-a l~ re n h ~i
20 degrees ~r~F}he~t and AF i5 in pounds per hour.
q~he AF ~ignal and the exha!Jst pre~sure ~ignal P6
is applied to calculator 86. ~ig. 7 graphically
illustra~e an exemplary function for determining the
factor FH~4, The FHR4 factor i8 a relationship
25 between the deviation of P6 from a de~ign exhaust
pres6ure value P6DES which r~sults in ~ perc~ntage
change in the deslgn heat rate value for th~
~:: turbine-generator system. A illu~trated in Fig. 7,
the instantaneous ~lope of the exhause pressure ~ s
: ~ :
~ " ' .
i7
17TU-2967
-Zl-
~ffected by the ratio of adju~ed flow ~P to ~he
design low value PLl. The ratio provide~ the
percentage of design flow. ~ignal F~R~ i6 supplied
to economic 10RS calculator 780
A6 1~ well ~nown ln the art, the
turbine-generator 6y8tem ha~ aasociated with lt a
daslgn hea~ rate ~alue ~t ~pe~lfl~ a percent~ge of
rated load. The design heat rate value for the
turhine-generator 5y8tem 18 dependent ln part upon
the turbine b~ing ~upplied with Btea~ at design
temperature T1Dæs and de~ign pressure PlDES~ Hence,
when Pl and T1 dævlate~ from the design values, the
design heat rate for the turbine system ch~nges. A
de~ign heat rate calculator gO provides means for
determinLning the substanti~lly instantaneous design
heat rate H3 for the sy~tem including the turbine and
~he electric generator. ~ de~ign heat rate signal H3
is generated by calculator 90. The ~ntrol ~alve
signal Vl, signal T1 and signal P1 are supplied to
calculator 90. The ~3 aignal is related to a
corrected percentage of flow (PCF2) through the
turbine ~yste~, and by comparing PCF2 to a data base
developed by the turbine generator manufacturer at or
af~er the inltial testing ~t the ~om~ ionlng of the
turbine-gene~ator u~lt, th~ design heat rAte ~i~nal
~3 is obtained. PCF2 can be calcula~ed by many well
known methods, one of which follows from the
equa~ions
PCF2-f(Vl~l(Pl/VOL~P1,T~))/(P1D~S/VO~(P1~ES,~1DES))]l/?
,.
,;,
67
17TIJ-2967
--22--
where f~V1) is the percent 8team flow through the
control valve, VOL(P1,T1) i8 the splecific volume of
the steam at the pressure and temperature P1, T1, and
YOL~PlDES, TlDES) is the design specific volume of
the ste~m at design pr~6 ure and design temperature
values. It is well known in ~he ~rt how to determine
percent steam flow through the ~ontrol valve a~ a
f~nction of V1~
Calculator 78 obtains FHR1 ~ignal, PHR2 6ignal,
FHR3 signal, F~R4 signal, electrical output ~ignal
W1, and H3 signal. Calculator 78 ha~ stored within
it a cost per unit heat factor CF at which the system
operates. In o~her words, boiler 14 output~ heat or
thermal energy at a certain cos~ per unit heat, such
as in dollars per million ~TU. ~enerally, calculator
7 a includes means for multiplying the several inputs
.- together along with ~ several conversion constant~
i, ,..~
thereby developing economic loss 6ignal~ displayable
in co~t per uni~ time. A main ~team temperature loss
signal LOSS1 ls developed by multiplying W1, F~ 3
and the cost per unit heat factor ~ignal CF, together
with a first con6tant. With re~pect to the steam
turbine sy~tem under di~cu~sion herein which includes
HP turbine ~a~, IP tur~ine 5~ and LP turbine 6D, the
main ~team temperature 1088 ~ignal LOSS1 i& added to
a reheat steam ~smperature loss signal LOSS2 to
~btain a total temperature 1068 ignal LOSS5. As is
well reco~nized in the art, if the st~am turbine
system included only one turbine ~echanic~lly coupled
to an electromagn~tic generator, main ~team
~. . .
, ~ .
. I
, .
6~
17TU-2967
--23--
1QSS signal LOSS1 would be dlrectly displayed ~o ~he
operator of that single turbine sy~tem~
One algorithm for determlnlng the ~in steam
tempera~ure 10~6 signal LOSS1 i~ as follows:
LOS$1~(~HR1lT1,%LOAD)/100)*H3~10 3~W1~106~24~CF*10 6
In the above equation, the main steam te~perature loss
signal ~OSS1 is di~playable in dollars per day~
The reheat ~team temperature loss ~ignal LOSS2
repre~ents the economic 108s of operating IP turbine
54 at a temperature and pressure different from the
~esign temperature and pressure. One algorithm for
determining the reheat ~team ~emperature loss signal
LOSS2 is as followfi:
3 6 -6
LOSS2=(FHR2~T4,~0AD)/100)*H3*10 ~Wl~tO *24~CFblQ
The economic loss of operating th~ steam turbine
system 30 ~t a certain pres~ure i8 provided by a
main steam pressure los~ signal LOSS3 which is
derived from the equation:
LOSS3~FHR3~Pt,~OAD~ 0)~H3~10 3*W1~106*24~CF*10 S
An exhaust pressure 108S signal LOSS4 relates the
e~onomic 108S of operatlng the steam ~urbine ~ystem at ~n
exhaust pres~ure P6, and one ~quation for deter~inlng the
exhaust pressure 1088 ~iqnal LO~S4 is ~s ~o~lows:
~ LOSS4-tPHR4lP6~AF~/1QO~H3*10 3~W1~106~24~CF*t0 6
:
~ ., ~ .
, .................... .
~2~i6~
17TU-2967
As ~tated ear~ier~ the total k~mperature
economic 10~8 LOSS5 is the ~um o~ LOS~1 ~nd LOSS~.
Total temperature lo 6 LOSS5, ~a~n ~tea~ pressure
los~ LOSS3 ~nd exhaust pre~ure lo8~ LO$~4 are
applied to oper~tor di~play 76. In thl~ ~annerD
operator 1~ ~ pres~nted, ~n dQll~rs p~r day, the
economic consequences o~ operati~g xtea~ turbine
~y~tem 30 at a ~ontrolla~le tempera~ure ~nd pre~sure.
The exhau~t pre~ure 108~ indi~ate~ that el~ment~
downstream of ~P turbine 60 are rai~ing the bac~
presæure and thereby affecting the exp~nsion of the
steam through the steam turbine ~y6tem generally. By
altering the control valve position V1, and the input
into boiler 14, operator 18 c~n affect the pre~sure
and temperature of the steam ~upply to steam turbine
system 30 to increase the thermal performan~e and
economic per~rmance of the syste~,. Operator display
76 also indicates electrical power output aignal Wt
and total control valve position V1 in megawatts and
percent re~pectively.
Fig. 8 illustrates the operator'~ di~play for
the operator thermal performance ~onitor, The
oper~tor ' ~ display may be a CRT or ot}ler human
readable mechanism. The component~ of tbe operator' 6
25 display haYe been explained hereinabovec ~8 18
recognized in the art, the da~a ~upplied t~ the
operator ' 8 di~play coulû be continuously recorded on
appropriate means by dat~ ~tored 8ubsy8tem 28. Al~o,
a~ well recognized in the art, the operator~'~ th~rmal
30 perfc~rmance monitor may be coupled 'co an ele~!tronic
.
,..
.
~` ~
~6~6~
~ 7TU 2967
--25--
control system which directly control~ 6team turbine
syste~ 30~ In this vi~w, the control ~yBtem would
have acceptable rangse of economic los8 value~. If
Bteam turbine ~y~em 30 wa~ not operating wlthin
S ~ho~e pre-establish~d r.anges, the ~lectronic control
8y8te~ would al~er the v~riouC oontrollable
para~eter~ to bring 8te~m turbine ~y~tem
30 within the accept~ble r~ng~s of operati~n, ~he
displ~y, ln Fig. 8, of ~aasured t~mperatureR,
pressure~ and their corresponding deviation from
design simply highlight selected area~ in steam
turbine ~y6te~ 30. The di8play al80 presents P2, P3,
P5 and kheir related deviations from design.
Data proce~sing ~ubsystem 24, illustrated i~
15 Fig. 1, also includ~-~ a re6ults engineer thermal
perfor~ance monitor. Generally, the results
engineer's th~rmal per~ormanee ~onitor calculates the
actual ~fficiency of the HP and ~P turbine, the
deviation from design heat rate for those turbines,
and the power lo~s ~ssociated with the st~am turbine
~ystem operating at an in~tantaneous supply
temperature, and instantane~us reheat temperature,
insta~tan~ou~ ~upply pressure and an ~n~t~ntaneous
exhau~t pressur~. Due to the result~ engineer'~
~S extensive technical training, edu~ation and
tur~ genera~or syQtem experience, he or 4he, when
presented with this information, can recommend
: ~intenance proc~dur~ or æubstantial chan~es in the
oveYa}l operation oP ~h~ steam ~urbine fiystem 30,
bo~ler 14, condensor 6B, and other rel~ted elements .
in the steam ~urbine plant~ Co~only, the results
engineer reviews the turbine ~ys~em performance over
.
2 ~ 6~ J l7TU-2967
2~-
a ~ubstantially long perlod of tl~e, ~uch a~ one
week~ as compared to the ~hift op0r~tor' Q BUpervi~ion
o~ the turbine ~ystQm oper~tion. ~ub t~nti~lly
longer p~rlod~ of tl~e ~re util$~d ~or long term
S trend analy~
Flg. 9 illu~tra~a ~ flow ch~rt ahow~ng the
functional aspects of a portlon of the re~ults
engineer'~ thermal perfor~ance ~onitor ~hlch i~
included in d~ta proc~ing ~ubsy~tem 24. Pri~arily,
Fig. 9 deal~ with ~eans for calculating the entha:ipy
of the steam entering and leaving the HP turbine and
IP turbine, converting tho~e enthalpy valuas to
efficiency values for the HP and IP turbine, and
sub~equently calculatlng the HP and IP devia~ion in
heat r~te from d~sign. ~n input enthalpy calculator
110 obtains temperature ~1 and pressure P1 a~ the
inlet of control valve 38. Calculator 110 ~ay
include.a data base which can be characterized by
Mollier diagram. Hence, the input enthalpy J1i f
20 the steam i~ calculated and a sîgnal i~ applied to an
actual ~P efficiency calculator 112. ~n output
enthalpy ~alculator i14 18 ~uppl ied wlth T3 3nd P3,
determines ~he output enthalpy J1~ of the steam,
~nd thereafter applie~ sign~l 31e to calcula~or
112. ~he slgnal J1i and ~ign~l Jle ~re
calculated on a substan~ially in~antaneou6 basis
with the ~en~lng of the temperature~ ~nd pre~ures.
Hence7 cal~ulator 112 i~ continu~lly u~ ~ting the
eff1ciency signal represent~tlve of the oper~ting
: 30 condition of HP turbine 48.
: An i6entropic output enthalpy calculator 116
.~ receiv~s T1, P1 and P3. The i~entropic enthalpy d~
e~h is bAsed upon tbe in8tant~n~0u8
temperature ~nd pres~ure reading~ and ~asume~ an
.~ , .
. ~ . . .. . . .... . .. ... . . ... . .. . . . . . . . ..... . . . . . .. . ... ... .. . ... ... ..
6~
17TU-2967
-27-
adiaba~ic ~nd rever3able proce~s in the steam turbine
and the control valv~. Thl~ ~alcul~tion 1B well
known in ~he art and ~ay be ob~ai~d fro~ a data base
charact~rized.~ a~ ~ Molli~r diAgram.
Calc~lator 112 obtains the ratlo be~ween the
actual enthalpy drop 5J1i-J1e) and ~he
i~entropic enthalpy drop (J1i-J1eth) and
generate~ E3 signal. That actual HP efficiency
signal E3 is ~upplied to a results engineer'fi displ~y
116 which is p~rt of the re~ult6 ensineer interface
sub ystem 27 ~llustrated in ~ig. 1.
The ePficiency of IP turbine 54 is also of
concern to the results engineer. Hence, calculator
11 a receives ~ignal T4 and 6ign~1 P4 6en~ed at the
15 inlet of IP turbine 54 and determines the input
enthalpy J2i for that turbine~ Calculator 120
receives 6ignal T5 and ~ignal P5, repre~enting the
condition of the ~te~m exlti~g IP turb1n~ 54, and
determines the output Pnthalpy ~ignal J2e.
Calculator 122 receives fiignal T4i ~ignal P4 and
signal P5 to determine the isentropic output entha}py
J~eth fcr IP ~urbine 54. The&e three enthalpy
signal~ are applied to an ac~ual IP ~fficienry
calculator 124. Cal~ulator 124 ~ubtracts output
enthalpy signal J2e from input enthalpy ~lgnal
J2i, a6 well ~ subtr~ct~ the i~entropic enthalpy
signal J2eth ~rom input enthalpy signal ~2i~
A ratio of the actual enthalpy drop ~nd i~entropic
enthalpy drop for ~P ~urbine 5~ produces the ac~ual
IP efficiency ~ignal E4. E4 is ulti~ately ~upplied
to r~8ult8 engineerls d~play 116.
, ,
~ Z ~8 - 17TU-2~67
A design efficiency calculator 126 obtains
control valve position signal Vl to determine
the substantially instantaneous design efficiency
of the steam turbine. The design efficiency
signal El is based upon the above input for the
steam turbine. Specifically, calcula-tor 126
includes therein a data base formulated
by the turbine-generator manufacturer or
established during the initial commissioning
of the turbine-generator unit. Signal El
could also be based upon the corrected
percentage of steam flow, PCF2, through the
turbine system if the boiler 14 did not
utilize fossil fuel. One of the methods of
determining PCF2 is disclosed by the algori-thm
discussed above in relationship to clesign
heat rate calculator 90 and utilizes Vl, Pl and
Tl as inputs.
Signal El 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
design, Hl, by subtracting the instantaneous
design HP efficiency El from the actual efficiency E3
and dividing the resultant by the instantaneous
design efficiency ~1 and a conversion factor. The
algorithm for the HP deviation in heat rate signal Hl
is as follows:
Hl = -(100* ( (E3-El)/El) )/6.7
The Hl signal is applied to result engineer's
display 116. The divisor 6.7 depends upon the
~ specific turbine design, and hence is exemplary only.
,.~.. : : : ,~
67
- 29 - 17~U 2~67
A design efficiency constant 132 for
the IP -turbine 54 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 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 IP efficiency signal E4. Calculator
13A subtracts signal E2 Erom signal Eg, divides
the resul-tant by signal E2 and multiplies by
a conversion factor to generate the IP deviation
in heat rate from design signal II2. One algorithm
for H2 follows:
H2 = ~(100* ( (E4-E2)/E2) )/10)
Signal ~2 is supplied to results engineer's
display 116 as is signal E2 and signal E4. The
factor 10 is exemplary only and relates to a
specific turbine system. As illustrated in
Fig. 9 t both the HP deviation from design signal
Hl and IP deviation from design signal H2 are
transmitted to other elements functionally shown
in Fig. 10.
Fig. 10 is a flow chart illustrating
3Q the remaining portion of the results engineer's thermal
performance monitor. sasically~ Flg. 10 relates to
the power losses associated with operating the s-team
;
,~
17TU-2967
--30--
turbine ~y~tem 30 at controllable temperature~ ar~d
pressures which may difer frorQ des:ign ~alues.
An initial temperature kilowatt loald correctian
factor t~LOAD1 ) c~lculator 1~0 ~6 supplied with
5 T1 and the percentage c: f rated load ~gn~l %I,O~ .
The function or determining factor ~LOAD1 is ar~
expression ba~ed upon the dev~tion of te~p rature T1
from 'che de~ign ten~perature T-1D~S which re~ults in a
percentage change in the design heat rate va) ue for
10 the turbine ~ystem. The 810pe 0f thi~ initial
temperature power expression i8 affected by 4~0AD
signal. One FLOAD1 function ifi graphically
illustrated in Fig. 4 by the lines ext~nding rom the
upper lef t quadrant to the lower right guadrant . In
a similar faah1on to the ~nltial temperature heat
rate correction factor functlon, P~1, de~cribed ln
rel~ionship to calculator 80 of ~ig. 3, the function
is based vn theoretical calcul~tiona whlch are
conf lrmed by f ield tests on actual tl~rbine sy tems .
The signal FLOAD1 i6 applied to a main steam
temperature power loss, W6, calcul~tor 142.
Calculator 142 is supplied with the electrical power
output ~ignal W1 and one method of calculating W6
i~ ~s f~llow~:
W6 ~ (PLOAD1(Tl,~LO~D)/100~W1
Signal W5 may be directly ~pplied to result6
engineer's display 116b or may be ~upplied to summer
144 as i}lustral:ed in Fig. 10.
A reheat temperature kilowa~ct load correct ion
(E~hOAD2) f~ctoe calcul~tor 146 iB ~upplied wlth T4
:
:,, .
67
17TU-2967
- 3 1 -
and 4~0AD. The Eunction for deterlDining the ~LOAD2
factor i~ an ~xpres~ion ba~ed upon the ~evlation of
temperature T4 from a reh~at design teloperature v~lue
T4DES which results in a percentage ~h~nge in the
5 de~ign heat ra~ value for th~ 'eurbine ~yste~. The
FLOAD2 uncti~n is graphically illustrated in ~iy. 5
and is generated subRtantially eimil~r t6:~ PEIR2
~LOAD 1 and ~HRl .
The ~LOAD2 signal is ~upplied to 2 reheat steam
tempera~ure power 108s, W7~ calculator 148 as is
signal W1. Calculator 148 divide~ the FLOAD2 factor
by ~ correction factor and multiplies by signal W1
as follows in one ~xemplary algorithm:
W7 ~ (FLOAD2~T4, ~LOAD)~100)~W1
Slgnal W7 is ~upplied to summer 144 wherein that
signal is added to signal W6 to provide a total
temperature power 1088 fii9nal W9. Signal W9 i8
u~timately pre3ented to re~ults engineer'~ display
1 1 6b .
An lnltial pressure kilowatt load correction .
factor (FLOAD3) calcu}ator 150 obtains Pt and
~6LOAD~ The funct~on for deter~ining the signal
FLOAD3 i~ ~n expres~ion based upon the deviation of
~ignal P1 ~rom PlDES ~hich re~ults in a percentage
~hange in the de~ign heat rat~ v~lue for the ~team
turb~ne 8y5tela. In a 6imilar fash~on to the initial
pre~sure heat r~te s:orr~ction ~ctor FHR3, the
F~OAD3 f actor has a slope which is af ected by the
percentage o r~ted load signal. One example of the
initial pressure ~orrection factor as it rela~e6 to
` ' .
.
67
l7TU-2967
-32
~hange~ in kilowatt load i~ graphi~ally illu~tr~ted
in Fig. 6. It i to be recQgnized that the FLOAD1
f~ctor, the PLOAD2 fac~or and the FLOA~3 factor
functions are e~tabli~hed in the ~ame manner as the
corre~ponding heat rate corr@stion f~ctor6 discus~ed
earlier.
The PLOAD3 signal is applied to a ~ain ~team
pressure power los~, W8, ~alculator ~52 as is
signal W1. Calculator 152 provides ~eans for
determining ~ignal W~ ~y dividing ~LOAD3 signal by
a conversion factor and multiplying by signal W1 as
follows:
W8 ~ -tFLoAD3(p1~Lo~D)/loo)*w1
Signal W8 is applied to di~play 116b.
A poor exhaust pressure power loss signal W3
indicates to the resultR engineer a power 10~8 based
upon unduly high turbine exha~st press~re du~ to
elements in the system down~tream of ~P turbine 60~
Signal W3 is generated by an exhau~t pre~sure power
loss calculator 154 whlch receives signal W1 and th~
exhaust pressure heat r2te correction ~actor signal
FNR~. The exhaus~ pre~ure heat rate correction
factor lgnal ~HR4 i~ generated by an appropr~ate
calculator 1S6. Calculator 156 and an ~djusted low,
AF, calculator 158 ~re ~ubstantially similar to
cal~ulator B6 and calculator 88 of Fig. 3. It 6bould
: be apprecia~ed tha~ the resul~ engineer'~ thermal
performance ~onitvr may be independent from the
: operator'~ thermal perfor~ance ~onitor or may be
~ 3~ combined wi~h the operator's monitor~ ~n ~he latter
t~
~2~i6~
17TU-2967
~ 3--
~ituation, dupli~tion of calculator 15~ and 156
would be unnecessary. One algorithm to obtain W3 is
as f ol lo~s:
W3 ~ [F~IR4(P6,AF)/( îO0 ~ FHR4(P6,P,F))]~Wl
An E~P and IP turbine ef f iciency power loss
calculator ï60 receive~ the ~IP deviation in hea~ rate
from design signal ~1 and the IP deviation in heat
rate from de6ign ~ignal ~12 as illu~trated in Fi~. tO.
5ignal W1 i~ also Rupplied to calculator 160~ An HP
and IP t~lrbine eff iciency power loss signal W2 is
calculated by multiplying signal ~11 by a conversion
factor, adding to the resultant signal H2 and by
multiplying the re~ulting sum by signal W1 and
another conYersian fa~tor. On~ equation for deriving
the HP and ~P efficiency power loss 6ignal W2 is as
follow6:
W2 ~ ((1.7~H1) ~ H2)~(W1~100)
Signal W2 i8 ~upplied to displ~y 1~Sb. The 1.7
conversion factor in the above equation is related to
the specific turbine 6ys~em. That actor illu~trate~
that the HP devlation in heat rate from design
contributes more to ~ power 105s th~n tha IP
deviation in heat rate from design. This greater
: effect i~ no~ed becau~e ~aller enthalp~ within the
25 ~P t~rbi:net a~ reflected in H1, r~duce the enthalpy
: : which ean be added to the ~team in the reheater.
Hence, the energy which can be extracted fro~ the
steam by~ the IP turb~ine is reduced.
:
:
: ~ ,....
6~
17TU-2967
3 JJ-
Design te~perature and pre~Bure data base 162
supplies the design pres~ure a~d tel~perature~ ~o the
result engineer'~ dlsplay 116b. Allso iupplied to the
re ults engineer's di6play 116b are all the 6ensed
pre6sures and temperature-~ P1, P29 ~P3~ ~4~ P5, P6 and
T1, T~ , T4 and TS. The origln of the~e ~ensed
~ignals are ~learly shown in Fig. 2.
Fig. 11 generally lllu~trate6 ,a re~ult
engineer's display which pre~ent~ the control valve
position V~, ~he de~ign ~fficlencie~ P,1 ~nd E2, the
actual efficiencies E3 and E4, the deviation in heat
rate from design H1 and H2, a~ well as the varioL1s
power los~ signa}s W~, W8, W2, and W3 and their
relat~on~hip to the m~a6ueed load or the electrical
power output signal W1.
A per~on of ord~nary ~kill ln the Ar~ recognizes
that the ~urbine-ge~er~tor ~y~tem can be oper~ted
beyond itq r~commended design parameters, i.e., T1
and P1 can be higher than T1DES and P1D~S. Carrying
this point further, the ~y tem can be operated at
higher efficiencies which re~ult in negative economic
losses la~ ~n the operator's monitor) and in negative
power los~es (as in the re~ult~ engineer'~ monitor).
The monitor~) discu~sed and claim2d herein ~re meant
to cover ~uch a situ~tion.
It i~ ~o be recogniz~d tha~ the operator 1 6
thermal perfor~ance monitor ~nd the re~ults
engineer'~ th r~al p~eformance ~o~itor ~ay be
~ombined into one qeneral ther~al perfor~ance
monitor. One of ordinary ~klll in the art would
recognize ~he fea~ibillty of ~uch a combina~ion. The
claims ~ppended hereto are meant to cov~r 3uch a
general thermal performance ~onltor.
,~
, . .. , . . .. ,, .,. . ... ...... ,.... ... . . . . . . . .. ...... .. .... . . ...... . ~
~66~7
17TU-2967
-3~-
~ hroughout the dicussion of tha ~mbodi~ent of
the present invention, ~te~m turbine sy tem 30
included HP turbine ~, IP turbine 54, and LP turbine
60, One of ordinary ~kill in the art would
S recognize th~t other steam turbine yste~s could
uti~ize the turbine thermal peror~ance monitor a
di~closed 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 ~team turbine. For
clarity ~he foregoing di~cu~slon only focused on a
three turbine system. ~owever, some of the claims
appended hereto relate to a ~ingle turbine Rystem.
~o diferentiate between the various sign~ls in
either aystem, lower ~ase letters identi~y ~ignals in
the single turbine 8y8t~m and upper cass letters
identify ~ignals in the multiple turbine system. For
-~ example, in the 6in~1e turb~ e ~ystem, the first
temperature is designated ~ and the first
substantially instantaneous design efficiency is
designated ne1U. In contras~, the ~orresponding
s ~nals in the mu}tiple turbine sy~tem are designated
n~ and ~E2~ respectively. This nomencl~ture is
used ~or clarity and is not ~Qant to be }imi~ing in
~ny ~ense.
From another perspective, A turbine ~ystem ~ay
include two or ~ore high pre~nure steam turbines
m~chanically coupled to ~n intermediate pr~s~ure
~ ~: turbine and ~ low pre~3ure turbine and ule~mataly
: 30 coupled to a electrio generator. One of ordinary
skill in the art could utilize the pres~nt inventiOn
by adding appropriate means to ~nclude this
6~
17TU-29~7
-36-
sdditional ~urblne's performance into the thermal
performance monitor. The clai~ appended hereto are
meant to cover auch a ~team turbine sy~tem~
Although several ~en90r8 are di~cussed to obtain
S P,T signals herein, ~t ehould be recogniz~d that
conditioning me~ns or o~her ail-~,afe mean~ could be
utilized with the senRors to in ure the integrity of
the inputs into the thermal perfor~ance monitor.
These conditioning means could be ~d~usted
periodically~ such as annually, to ~orrec~ the raw
P,T data~
One of ordinary ~kill in t~e art will recognize
that many types of electrical devices could be
~tilized as a thermal per~ormance mvnitor disclosed
herein. In one embodiment, a E~ewlett Packard HP 1000
minicomputer a3sociated with a ~et o~ Fortran
subr~utines ~e utiliz~d. In a second embodiment,
~S~ . rn, e ro co~nP~ter
an Intel ao86 ~ e~m~e~, manufa~tured by Intel
Corporation, was utilized with the ~ortran
subroutines. However, it is to be understood that
even though ~everal working embodiment6 utilized
: : digital electronic equipment, the operAtion of a
completely analog thermal perormance monitoring
device could be developed by one of ordinary ~kill in
25 the art as disclo~ed herein.
The claims appended hereto are meant to cover
all modifi~ation~ apparent to those individualS of
ordinary ~kill in the art. ~he recognition oP
variou~ ~onstant~ proportionali~ies, nu~bers and
conversion factors stated in the claims is not meant
to be limiting.
,. .
. ,~
, : ..
