CA1042290A - Turbine generator cycle for provision of heat to an external heat load - Google Patents
Turbine generator cycle for provision of heat to an external heat loadInfo
- Publication number
- CA1042290A CA1042290A CA243,699A CA243699A CA1042290A CA 1042290 A CA1042290 A CA 1042290A CA 243699 A CA243699 A CA 243699A CA 1042290 A CA1042290 A CA 1042290A
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- CA
- Canada
- Prior art keywords
- heat
- steam
- power plant
- extracted
- heater
- Prior art date
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Abstract
TURBINE GENERATOR CYCLE FOR
PROVISION OF HEAT TO AN EXTERNAL HEAT LOAD
ABSTRACT OF THE INVENTION
A steam turbine power plant having associated therewith a closed loop flow arrangement for extracting heat from the power plant and supplying the extracted heat to an external heat load. Included within the flow arrangement is a predetermined number of heater elements, each of which extracts steam having a predetermined heating capacity associated therewith from a predetermined number of separate locations within the power plant. The heat so extracted is transferred to a heat transfer medium flowing at a pre-determined flow rate within the closed loop arrangement. The extracted heat is exchanged to the heat load within a heat exchanger element connected within the flow arrangement.
The amount of heat extracted from the power plant is functionally related to, and automatically limited by, the flow rate of the heat transfer medium within the closed loop arrangement.
The flow rate of the heat transfer medium is itself func-tionally related to the flow rate of the motive fluid for the power plant.
PROVISION OF HEAT TO AN EXTERNAL HEAT LOAD
ABSTRACT OF THE INVENTION
A steam turbine power plant having associated therewith a closed loop flow arrangement for extracting heat from the power plant and supplying the extracted heat to an external heat load. Included within the flow arrangement is a predetermined number of heater elements, each of which extracts steam having a predetermined heating capacity associated therewith from a predetermined number of separate locations within the power plant. The heat so extracted is transferred to a heat transfer medium flowing at a pre-determined flow rate within the closed loop arrangement. The extracted heat is exchanged to the heat load within a heat exchanger element connected within the flow arrangement.
The amount of heat extracted from the power plant is functionally related to, and automatically limited by, the flow rate of the heat transfer medium within the closed loop arrangement.
The flow rate of the heat transfer medium is itself func-tionally related to the flow rate of the motive fluid for the power plant.
Description
BACKGROUND OF THE INVENTION
Field of the Invention .~ .
- This inventi.on relates to steam turblne power ' plants, and, ln particular, to a steam turblne power plant :~ havlng associated th.erewith'an assoclated' closed loop flow arrangement for extractlng heat from the power plant and supplying the heat so extracted' to an external heat loadO
.; Descript'ion of~_the Prlor Art:
I Recen~ly, emphasis has been placed on the realization ~ ,7 ;:~
. ~ :
.
, , ., ~' \'`
~"
.'.
. ' ,j~' ' .
115,890 of an economically attracti.ve '"dual-purpose"' power generation '. :'' fac~lity. adapted' to. ~ulflll a two-pronged' goal of simultaneous : .'' ~' el'ectric power:generation and brine des'alinizationO In such dual purpose 'faciliti.es', it has bee'n anticipated that -.:
the motive ~luid for the 'e.l'ec'tr:ic power gener'ation be '.
supplied:by a nuclear power'ed steam generator, while the .` ::' ' ~ .'' des'alinizati.on of brine 'is ef'fec'tuated' by the'application ~ '.:
of the "~lash ev'aporati:on" proces'sO
Brie'fly, flash'evaporation is a multi-stage 10 disti:llation process in which'sea water is progres'sively ~ -heated to. a predet'ermined' temperature under given pressure ' conditions and then introduced' into: a chamber maintained at a lower'pressure '~ust bel'ow the boiling point of ~ .
the hea:ted'brine.' As the 'hea'ted'brine 'enter's the lower : :
pres'sure chamber', the' reduced' pres'sure 'therein causes the brine solution to boil, or ~flash"', into steam. The steam ' so produced is condensed' and the`'fres'h water produced thereby ls conducted' away. It has bee'n anticipated' that the heat j ' , nec'es'sary to.raise the :temper'ature 'lev'el' of the brine be -'' 20 ex'tracted from th.e nuclear-fuel' steam turbine power'plant ; In the' prior art,. it .ls common practice to raise ` the 'temperature of the'brine 'soluti:on by conducting steam from one 'pred'et'ermined' ex'tracti:on locati:on within the power " : : .
plant direc'tly to. the brine 'hea't :ex'changer. The 'heat of the :
ex'tracted steam is the'r'e 'transferred' to: the'brine. The ' ' condensate. is returned' to:the'steam cycleO
~ Although'direc't :s.team ex'traction te:c'hniques have '.. ~;
'~ been succes'sful on small scale '(50 megawatt.. or les's) power :.
sta.ti:ons, th.ey' have 'litt.l:e 'applicability: for large capacity
Field of the Invention .~ .
- This inventi.on relates to steam turblne power ' plants, and, ln particular, to a steam turblne power plant :~ havlng associated th.erewith'an assoclated' closed loop flow arrangement for extractlng heat from the power plant and supplying the heat so extracted' to an external heat loadO
.; Descript'ion of~_the Prlor Art:
I Recen~ly, emphasis has been placed on the realization ~ ,7 ;:~
. ~ :
.
, , ., ~' \'`
~"
.'.
. ' ,j~' ' .
115,890 of an economically attracti.ve '"dual-purpose"' power generation '. :'' fac~lity. adapted' to. ~ulflll a two-pronged' goal of simultaneous : .'' ~' el'ectric power:generation and brine des'alinizationO In such dual purpose 'faciliti.es', it has bee'n anticipated that -.:
the motive ~luid for the 'e.l'ec'tr:ic power gener'ation be '.
supplied:by a nuclear power'ed steam generator, while the .` ::' ' ~ .'' des'alinizati.on of brine 'is ef'fec'tuated' by the'application ~ '.:
of the "~lash ev'aporati:on" proces'sO
Brie'fly, flash'evaporation is a multi-stage 10 disti:llation process in which'sea water is progres'sively ~ -heated to. a predet'ermined' temperature under given pressure ' conditions and then introduced' into: a chamber maintained at a lower'pressure '~ust bel'ow the boiling point of ~ .
the hea:ted'brine.' As the 'hea'ted'brine 'enter's the lower : :
pres'sure chamber', the' reduced' pres'sure 'therein causes the brine solution to boil, or ~flash"', into steam. The steam ' so produced is condensed' and the`'fres'h water produced thereby ls conducted' away. It has bee'n anticipated' that the heat j ' , nec'es'sary to.raise the :temper'ature 'lev'el' of the brine be -'' 20 ex'tracted from th.e nuclear-fuel' steam turbine power'plant ; In the' prior art,. it .ls common practice to raise ` the 'temperature of the'brine 'soluti:on by conducting steam from one 'pred'et'ermined' ex'tracti:on locati:on within the power " : : .
plant direc'tly to. the brine 'hea't :ex'changer. The 'heat of the :
ex'tracted steam is the'r'e 'transferred' to: the'brine. The ' ' condensate. is returned' to:the'steam cycleO
~ Although'direc't :s.team ex'traction te:c'hniques have '.. ~;
'~ been succes'sful on small scale '(50 megawatt.. or les's) power :.
sta.ti:ons, th.ey' have 'litt.l:e 'applicability: for large capacity
-2-'~ ', ' ' '' 1~5,890 , _~
4Z~O
water desalinization power plants:. Also, ex'traction of -volumes of stea'm larger' than a predet'ermined' amount from only one locati.on within the power' plant may deleteriously affect :the power generati:on cycle and require 'extensive modificati.ons from current des'ign and oper'ating experienceO
In sum, direc't steam ex'traction as the 'hea't source for flash evaporati.on desalinizati:on is of limited usefulnessO
To provide 'heat nec'es'sary for larger scale water-making capabiliti.es, it has bee'n proposed' to: utilize ' a "bob-tailed" turbine apparatus of a rel'ativeIy large size, on th.e 'order' of 1200 MoWo In such'a scheme, the :
exhaust of the'steam cycle 'is direc'tly introduced' as the ' hea't source for the' brine heater'. The 'hea't of condensation of the' exhausted s.team raises' the 'temperature 'of th.e brine . '' soLution, whi'le'the condensate:ret`urns to: th.e`'steam generator el'ement .of the power' plantO:
The main disadvantage 'of such'an arrangement arises f'rom the 'substl.tu.ti.on of the`brine hea'ter for the standard '.
.' condenser' el'ement : Such 'a substitu:tion raises' the back pressure '-- th.e pres'sure 'immed'iately downstr.eam of the 'last `, array of rota.ting blades' -- so that :ther'e'is little or no -power' generation from thi's blade arrayO It :is apparent that such 'a condition would adver'sely affec't the output and ' ~ :
;l. ' : .:::
; reliability of th.e 'el'ec'tr:ical generating plantO.
In order' to: obviate:'thes'e difficulti:es' due to the increased'back pres'sure,' it :has been sugges'ted' that the '~
rota.ting blades' in th.e'last array be 'shortened', or "bob- ~-'. ' tailed", to; a hei'ght':les's than the blade :hei'ght' for a normal ~' last row blade 'of commensurate:'power capability.O This . '~
ta:iloring of blade height's: to: mee't':sys.tem requirements. and : : -,`: ,,.
45,890 ' 9~
. .
the resulting highe'r:power'.density:requires' specially des'igned "~
blades for ea'ch individual applicati:on This, of course, precludes' the use :of proven and rel'iable 'standardized components. The probability: of failure 'increa'ses commensur- ' :
ateIy, and the:'efficiency and capability: of the :electrical .
plant :is permanently impairedO
: In additi.on, such'plants may not be dGwned for - repair without sumultaneously halting desalinization procedures. Conver'sely, as long as the producti:on of fresh ', 10 water is required, the 's.team plant must be operatedO Still further, by prcviding speclally tailored' blades, there may be generate.d' sev'er'e 'contr:ol problems, especially in the overspeed contr.ol, due :to: the 'loss of rotati:onal inertiaO -' ' .
.
It .is apparent that .there 'is required' a steam power generation system having associated' the'rewith an ~.
efflcient heat .cyole ~or large 'capability. water desalinization able to. del'iver: the'rnaximum heat :transfer'yet still utilizing standardized proven cornponen'ts.. It .is also patent that a system and he'a't cycle uti.lizing he'at :ex'tracted from a .. ~
.~ 20 multiplicity. of sources' withi'n the 'power' plant .to supply .' the he'at load is a def'inite:'improvement :over' prior art '. ..
. systems O In additi.on, a he'a't cycle adaptable to divert .
steam to.provlde hi'ghe'r or lower' water' capability depending ~.
upon peak electr.icity: demand, and to provide water'desalini- . ..
'i zation during periods of turbine inactivity, is also advanta-l .
:~ geous over' the pres'ent :art ~' SUMMARY O~ THE INVENTION ' . .
The 'steam turbine power' plant embodying the .:
tea'chi'ngs of this inventi:on provides he`a't to. an external heat load and overcomes' the''disadvantages' mentioned' in the -4~
: :
,'' ', ' . 45,890 ~ ~ 4 Z Z 9 ~ ~' prior art .in a novel:, useful, and unobvious manner.
The 'ste:am turbine power plant :comprises;, in series, ' a steam generator element,: a high'pressure,~ël'ement,. a low :j pressure 'turblne 'el'ement,: and a condenser' elementO A
~, closed loop flow arrangement,:which 'confines' and guides a heat transfer med'ium therein, is cooperativeIy assoclated' with the' power'plant :to. extract heat :therefrom and supply the heat so ex'tracted' to:the 'heat -loadO The'flow arrangement includesl at .least tw.o heater' elements: connec'ted to a heat '. .
exchange 'el'ement :and to: a flow contr:ol deviceO The heater extracts: hea:t,.in the :form of steam, from at .least two ' differ'ent ex'tracti.on locations, ea'ch having a different heating . :
.~ ~; ..... .
I capacity.associated' therew'ith,' within the power plantO ':' . ' .1 Provision may be made for a pred'et'ermined number of different '. ~ ' .' ex'traction locations or other' he`a't sources' from the'power '~
! . .
:~ gener'atlon cyclec~ The heat :thus ex'tracted' is transported ... :
by the' heat transfer med'ium to. the hea't exchange element,. . :;:
;' where lt .is ex'changed with'the heat loadO The amount of .
.1 heat extracted' ~rom the' power plant is functi:onally reIated ~ :
.~. 20 to. the flow rate.'of th.e' heat :transfer' med'iumO The flow .' ~'~
rate 'of the heat .transfer' med'ium is contr:olled'by the 'flow ~ control device. '. . .- .
'i~ In order' to: provide capability: for hea't transfer ".
.' during off-peak hours of the power plant,. one heat source ':
location provides' a bypass from the'steam gener'ator to a hea:ter: el'ementO In the :event :of increased' elec'tric demand, the bypass may be 'closedO
' It .is an ob~ect :of this inventi:on to provide a ~ steam turbine'power plant having an associated he'at transfer .. ' ` 30 cycle `able to. ex'tract .th.e 'grea.te:s't amount :of heat while ':
: -5- .:
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using standardized:power: plant :el'ements: and not requiring specialized: component des'ignO
. It :is a furthe'r ob~ec't :of this inventi:on to, efficiently transfer heat :to: an associated heat -load from a plurality of hea't sources'within the''power plant,: thus not :overtaxing any ' one 'single ~ex'tracti:on zoneO It :is yet' a furthe'r object ,to provide a closed' loop heat :flow arrangement associated with'a steam turbine power plant in which'the amount :of heat :ex'tracted' . ..
from the power~plant .is direc'tly controlled by the' flow rate, of 10 the` heat .trans~er' med'ium flowing within 'the'flow arrangementO. ;~
j It :is a sti.ll further ob~ec't :of the''invention to. provide a heat , ', flow arrangem'ent associated' with'a steam turbine power plant `
adapted so that .th,e requirement:s: of the''elec'trical load, heat : ''. .
' load or both~' may be met',.dep'endlng upon the' relative demand , placed on ea'oh,' in an ea'sily regulable manner It is another ,:~ ' '' obJec't of the 'lnventi:on to.provide 'a flow arrangement associated ', with'a steam power' plant ,that is operable 'ev'en during non .. ':.
; productive periods of the power' plant~: Other' ob~ec'ts of , the invention will become 'clear in the 'following detailed , 20 descripti:on of the :pref'erred' embodiment.: --,, BRIEF DESCRIPTION OF THE DRAWING ~ ' The inventl.on will be more 'fully under'stood from the ' . ::' ' following det'a.iled' des'criptl:on, taken in connec'tion with. , ' the accompanying drawing, in whi'ch:' ~' The Figure 'is a sche'mati:c repres'enta:ti.on of a steam turbine power'plant having a he'at:tr:ansfer' arrangement , associated therewith'which'embodies' the 'teachings of the inventionO ;, S DESCRIPTION 0~ THE PREFERRED EMBODIMENTS - '' - - -- ~:
' 30Ref:er'ring to: thb Figure,' ref'erence 'number 10 ~ :
; -6- -. , '' ''`' ' 45,890 ~.0422~C~
, refers to. a steam turbine power plant having associated therewith a sep'arate:'closed'-loop hea't transfer cycle 12 adapted to. ex'tract heat :from the 'power plant .10 and apply the' heat so ex'tracte.d' to: a sep'arate heat load 13 .
The power' plant .10 is a standard steam power generation facility comprising, in ser'ies' connec'tion, a steam flow .-' passing from a steam gener'ator el'ement 16, a high pressure . :
turbine 'elemen't :18, low pres'sure 'turbine 'el'ements. 20, and ''~
a condenser' 22. Each 'of the''turbine 'el'ements: are mechani- :. '- '' 10 cally linked on a common shaft :24 and connec'ted' to. an elec- .
tr.ical generator el'ement :260 The''turbines' convert high '- :'' temperature and hi'gh'pres'sure 'energy of the moti.ve steam ' ;... ' to.rota.ti;onal ener'gy of the 'shaf t 24, which'is in turn conver'ted, ~ '' by the generator 26, to: el'ec'trical ener'gy for a related .. ':
el'ec'trical load 280 : ~ ~
' In plants.such'as th:i's, the''steam gener'ator ` .:
el'ement .16 normally conver'ts: fee'd' water to.steam by '~ .: .
applylng thereto. hea't .ta.ken from a nuclear fuel' reactor element 290 Howev'er', it .ls to: be understood that although :' :: '' 20 the plant .10 to.be des'cribed' her'ein is a nuclear power :-~
plant,. the 'teachi'ngs of this invention apply equally well , .
. for both'nuclear and fossil fuel' applicationsO : ' :' High 'pres:sure,' high'temperature motive 'steam is ;.
., ~;, ~ " .
' conducted from the''ste:am generator el'ement :16, through a '. :
' series: of stop valves' indicated' at :numeral 30 and an array ' .
. ~ ., .
; of flow contr.ol valves: indicated' at :32, and into. the inlet ~: ' ` of the' high'pres'sure :turbine 18, thi's steam flow being ` .
illustrated' by ref'er'ence 'arrows 34 Although the high '' pres'sure 'turbine :el:em'ent :18 is illustr:ated' as being a double ' 30 flow apparatus, it .is of course,' under'sto:od, that any - 7 - . . - . .
: .
~', , . 45,890 . ~
~i42~1(lt suitable high pressure turbine'element may be utilizedO
Similarly, although ther'e 'is shbwn a bank of three, double-flow low pres'sure turbine :elements: 20, it is also to be ''~
understo:od that any suitable number of low pres'sure elements.
of any suitable type, dep'ending upon the 'electrical power system paramet:er:s, may be used'. The point worthy of note.
is that whate.v'er th:e 'number and type 'of turbine 'elements. ~.
chosen, the elements so chosen are standard units: adapted to: conver't steam ener'gy to:rotati:onal mec'hanical energy. .
Ther:e 'is require'd litt:l:e alterati:on to: any of the 'turbine el'ements chosen in order' to:practi:ce 'the 'teachings of this .~.
inventi:on and supply heat :to: the separate, closed'-loop heat '.
'' cycle 12. .
The'r'e may be provided', upsteam of the'stop valves' 30, suitable 'hi'gh pressure 'taps, as at :36, to supply moti.ve fluid for auxiliary steam system services, such'as steam for the''gland seals disposed about the shaft : 24, and steam to.the' air e~'ec'tors locate~d thr'oughout .the ' .:
system but .omitt:ed' here 'for clarlty~. After expanding through'th.e` hl'gh'pressure turbine el'ement .18, the steam is exhausted' ther:efrom, as shown by the' flow arrow 38 ~ : -.
and is conducted into.a combined moisture separator~
rehea'ter element :(MS-R) 40 where 'the steam ex'hausted .~.': ' 'i` from the'hi'gh pressure turbine 'is raised' in temperature before 'ex'iting th.e' MS-R 40, as shown at :42 Steam for the ' ;
I reheating functi.on of the''MS-R 40 is usually taken from ;' a tap located'upstr:eam of the 'stop valve '30, but such a ~:
' connection has bee'n omitt.ed' from the Figure for clarityO
:~ From th.e :ex'it :42 of the MS-R 40 the 'steam flow . 30 passes through parallel inlet'.conduits. 44, each having disposed' ther'eln an array of stop valves' 46 and interceptor . ~ ~
~ . ~l5,890 . --~
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valves 48 3 into. the':inlet's: o~ the 'low pres'sure 'turbine el'ements. 20, the :flow indicated' by reference arrows 50. :.
The ste:am expands through 'the 'low pres'sure 'turbine elements ' ;;? 20 and exhausts: ther:efrom, as shown at arrows 52, into the ' .:
.i condenser 220 Her'e 'the :steam is returned' to. the 'liquid sta.te. ln th.e Iform of condensate~' .
, ~ . : . .
.~- From th:e:'outlet':of the 'condenser 22, the ' ': condensate: is conducted', as shown by arrow 54, to a cc~densate ' pump 56 The 'condensate pump 56 pumps the 'condensate from ' :.
:
, 10 the :condenser: 22 through'a series' of ~eedwater' he'aters 58, ' 60, 62 and 64c The 'feedwater hea'ters have 'as their function, :.
the ta~k of raislng the :temperature 'of the 'condensate passing ' '~
l ther'ethrough'to.a hi'gher' temperature 'ln anti.cipation of the rel'ntroducti:on of the'condensate:'to: the''steam generator 160 ' ' ":.
'. Hea't for th.l's task iæ supplied'by ex'tracting steam ~rom pre~
sel'ec:ted' ex'traction zones' withi'n the''turbines' 18 and 200 .
As seen in the 'figure,' the''heater' 58 ls supplled'wlth'extrac .
tion steam ta.ken from a first pred'et'ermined' extractlon zone 66 within the':low pres'sure 'turbines' 200 The''steam extracted .~:~
;~ 20 ~rom zone '66 is conducted' through conduits: 68 lnto the reheater 58 .~' as lllustrate.d'by flow arrows 700 Slmllarly, steam ls ex- ;' tracted from a second pred'et'ermined' ex'traction zone 72 wlthin th:e 'low pres'sure :turbines' 20, through'conduits. ' 74 and into.the reheater' 60, the''flow being shown by reference . arrows 760 ~ :
.,. ,, ", ., :'', ,'.
. :i ., :' ', ' :' ' _g_ : , ~,, ., ", . ~
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. 45,890 ~'''^' ~,,'.
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In like manner, steam is extracted from a .
third predetermined extraction zone 78 within the low pressure turbine 20 and conducted through conduits 80 into : .
' the third reheater 62, this flow being illustrated by :.
reference arrows 82. As is apparent, each of the extraction zones66, 72 and 78 extracts steam from within the turbine 20 at a higher te-mperature and pressure condition, and thus the steam so extracted has associated therewith an ~-~ increasingly higher heat capacity. In order to fully lO utilize the heat content of the extracted steam, the :
drains of the reheaters 62, 60 and 58 are cascaded into each other, as illustrated by flow arrows 84 and 86. The ;-drain from the reheater 58 is conducted, as shown by arrow ~ .
88, into the condenser 22. Some plants provide, intermediate .
between the condensate pump 56 and the first feedwater ~:
heater 58, a condenser which returns gland sealing steam .
. to the liquid state. The drain from the gland condenser, .l although omitted for clarity, enters into the main `~ condenser at a point intermediate between the drain of the .
l 20 feedwater heater 58 and the condenser 22. -:! :
As seen from the figure, the heater 64 derives ;:
, its heat from steam extracted from a predetermined .l extraction zone 90 within the high pressure turbine 18, through conduits 92, the flow being illustrated by flow arrows 94.
.~ A boiler feed pump 96 is located downstream of l the heater 64 and`pumps the nloOw-heated condensate through :
"" j ., ::
45~890 ; '~ ~'.' '', ' ~',' ' ~0 4Z~9 a final feedwater heater 98~ From the final feedwater heater 98 ~ the condensate, now known as boiler feedwater, ~:
.- :
is conducted to the s-team generator 16 to complete the steam power plant loop 10, the flow being illustrated by .
reference arrow 100. The final feedwater heater 98 utilizes steam extracted from a second predetermined ~ :
i, . -extraction zone 102 located within the high pressure .:.... :
. turbine 18~ the steam being conducted through conduits .
` 104 ~ as shown by flow arrows 106 ~ As seen from the figure, ~
10 the second predetermined extraction zone 102 occurs at a ~ : :
location within the high pressure turbine 18 that has ~-associated with it a greater heat capacity than does the ~. .
steam from extraction zone 90. In order to efficiently ~ ~ :
; extract all available energy from the higher heat capacity steam, the drain of the final feedwater heater 98 is cascaded, as shown by arrow 108~ into the heater 64~ The ~.
" . ~.
draln from the heater 64 is itself pumped by a drain pump `~
.j (not shown) lnto the condensate flow to a point (not shown) -, lmmediately upstream o~ the boiler feed pump 96~ For .. ~
; 20 completeness, the drain from the moisture separator .. ;
.~ por-tion of the MS-R 40 also is collected and pumped by ~ .
the drain pump (not shown) to the point (not shown) ~ immediately upstream of the boiler feed pump 96~ Also :
;~y omitted from the figure for clarity is the connection , :
. between the drain of the reheater portion of the MS-R 40 . and the final feedwater heater 98 :~ In order to provide motive power for the boiler . ~eed pump 96 ~ there is provided a boiler feed pump drive ;l turbine 110, which is linked mechanically by a shaft 112
4Z~O
water desalinization power plants:. Also, ex'traction of -volumes of stea'm larger' than a predet'ermined' amount from only one locati.on within the power' plant may deleteriously affect :the power generati:on cycle and require 'extensive modificati.ons from current des'ign and oper'ating experienceO
In sum, direc't steam ex'traction as the 'hea't source for flash evaporati.on desalinizati:on is of limited usefulnessO
To provide 'heat nec'es'sary for larger scale water-making capabiliti.es, it has bee'n proposed' to: utilize ' a "bob-tailed" turbine apparatus of a rel'ativeIy large size, on th.e 'order' of 1200 MoWo In such'a scheme, the :
exhaust of the'steam cycle 'is direc'tly introduced' as the ' hea't source for the' brine heater'. The 'hea't of condensation of the' exhausted s.team raises' the 'temperature 'of th.e brine . '' soLution, whi'le'the condensate:ret`urns to: th.e`'steam generator el'ement .of the power' plantO:
The main disadvantage 'of such'an arrangement arises f'rom the 'substl.tu.ti.on of the`brine hea'ter for the standard '.
.' condenser' el'ement : Such 'a substitu:tion raises' the back pressure '-- th.e pres'sure 'immed'iately downstr.eam of the 'last `, array of rota.ting blades' -- so that :ther'e'is little or no -power' generation from thi's blade arrayO It :is apparent that such 'a condition would adver'sely affec't the output and ' ~ :
;l. ' : .:::
; reliability of th.e 'el'ec'tr:ical generating plantO.
In order' to: obviate:'thes'e difficulti:es' due to the increased'back pres'sure,' it :has been sugges'ted' that the '~
rota.ting blades' in th.e'last array be 'shortened', or "bob- ~-'. ' tailed", to; a hei'ght':les's than the blade :hei'ght' for a normal ~' last row blade 'of commensurate:'power capability.O This . '~
ta:iloring of blade height's: to: mee't':sys.tem requirements. and : : -,`: ,,.
45,890 ' 9~
. .
the resulting highe'r:power'.density:requires' specially des'igned "~
blades for ea'ch individual applicati:on This, of course, precludes' the use :of proven and rel'iable 'standardized components. The probability: of failure 'increa'ses commensur- ' :
ateIy, and the:'efficiency and capability: of the :electrical .
plant :is permanently impairedO
: In additi.on, such'plants may not be dGwned for - repair without sumultaneously halting desalinization procedures. Conver'sely, as long as the producti:on of fresh ', 10 water is required, the 's.team plant must be operatedO Still further, by prcviding speclally tailored' blades, there may be generate.d' sev'er'e 'contr:ol problems, especially in the overspeed contr.ol, due :to: the 'loss of rotati:onal inertiaO -' ' .
.
It .is apparent that .there 'is required' a steam power generation system having associated' the'rewith an ~.
efflcient heat .cyole ~or large 'capability. water desalinization able to. del'iver: the'rnaximum heat :transfer'yet still utilizing standardized proven cornponen'ts.. It .is also patent that a system and he'a't cycle uti.lizing he'at :ex'tracted from a .. ~
.~ 20 multiplicity. of sources' withi'n the 'power' plant .to supply .' the he'at load is a def'inite:'improvement :over' prior art '. ..
. systems O In additi.on, a he'a't cycle adaptable to divert .
steam to.provlde hi'ghe'r or lower' water' capability depending ~.
upon peak electr.icity: demand, and to provide water'desalini- . ..
'i zation during periods of turbine inactivity, is also advanta-l .
:~ geous over' the pres'ent :art ~' SUMMARY O~ THE INVENTION ' . .
The 'steam turbine power' plant embodying the .:
tea'chi'ngs of this inventi:on provides he`a't to. an external heat load and overcomes' the''disadvantages' mentioned' in the -4~
: :
,'' ', ' . 45,890 ~ ~ 4 Z Z 9 ~ ~' prior art .in a novel:, useful, and unobvious manner.
The 'ste:am turbine power plant :comprises;, in series, ' a steam generator element,: a high'pressure,~ël'ement,. a low :j pressure 'turblne 'el'ement,: and a condenser' elementO A
~, closed loop flow arrangement,:which 'confines' and guides a heat transfer med'ium therein, is cooperativeIy assoclated' with the' power'plant :to. extract heat :therefrom and supply the heat so ex'tracted' to:the 'heat -loadO The'flow arrangement includesl at .least tw.o heater' elements: connec'ted to a heat '. .
exchange 'el'ement :and to: a flow contr:ol deviceO The heater extracts: hea:t,.in the :form of steam, from at .least two ' differ'ent ex'tracti.on locations, ea'ch having a different heating . :
.~ ~; ..... .
I capacity.associated' therew'ith,' within the power plantO ':' . ' .1 Provision may be made for a pred'et'ermined number of different '. ~ ' .' ex'traction locations or other' he`a't sources' from the'power '~
! . .
:~ gener'atlon cyclec~ The heat :thus ex'tracted' is transported ... :
by the' heat transfer med'ium to. the hea't exchange element,. . :;:
;' where lt .is ex'changed with'the heat loadO The amount of .
.1 heat extracted' ~rom the' power plant is functi:onally reIated ~ :
.~. 20 to. the flow rate.'of th.e' heat :transfer' med'iumO The flow .' ~'~
rate 'of the heat .transfer' med'ium is contr:olled'by the 'flow ~ control device. '. . .- .
'i~ In order' to: provide capability: for hea't transfer ".
.' during off-peak hours of the power plant,. one heat source ':
location provides' a bypass from the'steam gener'ator to a hea:ter: el'ementO In the :event :of increased' elec'tric demand, the bypass may be 'closedO
' It .is an ob~ect :of this inventi:on to provide a ~ steam turbine'power plant having an associated he'at transfer .. ' ` 30 cycle `able to. ex'tract .th.e 'grea.te:s't amount :of heat while ':
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using standardized:power: plant :el'ements: and not requiring specialized: component des'ignO
. It :is a furthe'r ob~ec't :of this inventi:on to, efficiently transfer heat :to: an associated heat -load from a plurality of hea't sources'within the''power plant,: thus not :overtaxing any ' one 'single ~ex'tracti:on zoneO It :is yet' a furthe'r object ,to provide a closed' loop heat :flow arrangement associated with'a steam turbine power plant in which'the amount :of heat :ex'tracted' . ..
from the power~plant .is direc'tly controlled by the' flow rate, of 10 the` heat .trans~er' med'ium flowing within 'the'flow arrangementO. ;~
j It :is a sti.ll further ob~ec't :of the''invention to. provide a heat , ', flow arrangem'ent associated' with'a steam turbine power plant `
adapted so that .th,e requirement:s: of the''elec'trical load, heat : ''. .
' load or both~' may be met',.dep'endlng upon the' relative demand , placed on ea'oh,' in an ea'sily regulable manner It is another ,:~ ' '' obJec't of the 'lnventi:on to.provide 'a flow arrangement associated ', with'a steam power' plant ,that is operable 'ev'en during non .. ':.
; productive periods of the power' plant~: Other' ob~ec'ts of , the invention will become 'clear in the 'following detailed , 20 descripti:on of the :pref'erred' embodiment.: --,, BRIEF DESCRIPTION OF THE DRAWING ~ ' The inventl.on will be more 'fully under'stood from the ' . ::' ' following det'a.iled' des'criptl:on, taken in connec'tion with. , ' the accompanying drawing, in whi'ch:' ~' The Figure 'is a sche'mati:c repres'enta:ti.on of a steam turbine power'plant having a he'at:tr:ansfer' arrangement , associated therewith'which'embodies' the 'teachings of the inventionO ;, S DESCRIPTION 0~ THE PREFERRED EMBODIMENTS - '' - - -- ~:
' 30Ref:er'ring to: thb Figure,' ref'erence 'number 10 ~ :
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, refers to. a steam turbine power plant having associated therewith a sep'arate:'closed'-loop hea't transfer cycle 12 adapted to. ex'tract heat :from the 'power plant .10 and apply the' heat so ex'tracte.d' to: a sep'arate heat load 13 .
The power' plant .10 is a standard steam power generation facility comprising, in ser'ies' connec'tion, a steam flow .-' passing from a steam gener'ator el'ement 16, a high pressure . :
turbine 'elemen't :18, low pres'sure 'turbine 'el'ements. 20, and ''~
a condenser' 22. Each 'of the''turbine 'el'ements: are mechani- :. '- '' 10 cally linked on a common shaft :24 and connec'ted' to. an elec- .
tr.ical generator el'ement :260 The''turbines' convert high '- :'' temperature and hi'gh'pres'sure 'energy of the moti.ve steam ' ;... ' to.rota.ti;onal ener'gy of the 'shaf t 24, which'is in turn conver'ted, ~ '' by the generator 26, to: el'ec'trical ener'gy for a related .. ':
el'ec'trical load 280 : ~ ~
' In plants.such'as th:i's, the''steam gener'ator ` .:
el'ement .16 normally conver'ts: fee'd' water to.steam by '~ .: .
applylng thereto. hea't .ta.ken from a nuclear fuel' reactor element 290 Howev'er', it .ls to: be understood that although :' :: '' 20 the plant .10 to.be des'cribed' her'ein is a nuclear power :-~
plant,. the 'teachi'ngs of this invention apply equally well , .
. for both'nuclear and fossil fuel' applicationsO : ' :' High 'pres:sure,' high'temperature motive 'steam is ;.
., ~;, ~ " .
' conducted from the''ste:am generator el'ement :16, through a '. :
' series: of stop valves' indicated' at :numeral 30 and an array ' .
. ~ ., .
; of flow contr.ol valves: indicated' at :32, and into. the inlet ~: ' ` of the' high'pres'sure :turbine 18, thi's steam flow being ` .
illustrated' by ref'er'ence 'arrows 34 Although the high '' pres'sure 'turbine :el:em'ent :18 is illustr:ated' as being a double ' 30 flow apparatus, it .is of course,' under'sto:od, that any - 7 - . . - . .
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~i42~1(lt suitable high pressure turbine'element may be utilizedO
Similarly, although ther'e 'is shbwn a bank of three, double-flow low pres'sure turbine :elements: 20, it is also to be ''~
understo:od that any suitable number of low pres'sure elements.
of any suitable type, dep'ending upon the 'electrical power system paramet:er:s, may be used'. The point worthy of note.
is that whate.v'er th:e 'number and type 'of turbine 'elements. ~.
chosen, the elements so chosen are standard units: adapted to: conver't steam ener'gy to:rotati:onal mec'hanical energy. .
Ther:e 'is require'd litt:l:e alterati:on to: any of the 'turbine el'ements chosen in order' to:practi:ce 'the 'teachings of this .~.
inventi:on and supply heat :to: the separate, closed'-loop heat '.
'' cycle 12. .
The'r'e may be provided', upsteam of the'stop valves' 30, suitable 'hi'gh pressure 'taps, as at :36, to supply moti.ve fluid for auxiliary steam system services, such'as steam for the''gland seals disposed about the shaft : 24, and steam to.the' air e~'ec'tors locate~d thr'oughout .the ' .:
system but .omitt:ed' here 'for clarlty~. After expanding through'th.e` hl'gh'pressure turbine el'ement .18, the steam is exhausted' ther:efrom, as shown by the' flow arrow 38 ~ : -.
and is conducted into.a combined moisture separator~
rehea'ter element :(MS-R) 40 where 'the steam ex'hausted .~.': ' 'i` from the'hi'gh pressure turbine 'is raised' in temperature before 'ex'iting th.e' MS-R 40, as shown at :42 Steam for the ' ;
I reheating functi.on of the''MS-R 40 is usually taken from ;' a tap located'upstr:eam of the 'stop valve '30, but such a ~:
' connection has bee'n omitt.ed' from the Figure for clarityO
:~ From th.e :ex'it :42 of the MS-R 40 the 'steam flow . 30 passes through parallel inlet'.conduits. 44, each having disposed' ther'eln an array of stop valves' 46 and interceptor . ~ ~
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valves 48 3 into. the':inlet's: o~ the 'low pres'sure 'turbine el'ements. 20, the :flow indicated' by reference arrows 50. :.
The ste:am expands through 'the 'low pres'sure 'turbine elements ' ;;? 20 and exhausts: ther:efrom, as shown at arrows 52, into the ' .:
.i condenser 220 Her'e 'the :steam is returned' to. the 'liquid sta.te. ln th.e Iform of condensate~' .
, ~ . : . .
.~- From th:e:'outlet':of the 'condenser 22, the ' ': condensate: is conducted', as shown by arrow 54, to a cc~densate ' pump 56 The 'condensate pump 56 pumps the 'condensate from ' :.
:
, 10 the :condenser: 22 through'a series' of ~eedwater' he'aters 58, ' 60, 62 and 64c The 'feedwater hea'ters have 'as their function, :.
the ta~k of raislng the :temperature 'of the 'condensate passing ' '~
l ther'ethrough'to.a hi'gher' temperature 'ln anti.cipation of the rel'ntroducti:on of the'condensate:'to: the''steam generator 160 ' ' ":.
'. Hea't for th.l's task iæ supplied'by ex'tracting steam ~rom pre~
sel'ec:ted' ex'traction zones' withi'n the''turbines' 18 and 200 .
As seen in the 'figure,' the''heater' 58 ls supplled'wlth'extrac .
tion steam ta.ken from a first pred'et'ermined' extractlon zone 66 within the':low pres'sure 'turbines' 200 The''steam extracted .~:~
;~ 20 ~rom zone '66 is conducted' through conduits: 68 lnto the reheater 58 .~' as lllustrate.d'by flow arrows 700 Slmllarly, steam ls ex- ;' tracted from a second pred'et'ermined' ex'traction zone 72 wlthin th:e 'low pres'sure :turbines' 20, through'conduits. ' 74 and into.the reheater' 60, the''flow being shown by reference . arrows 760 ~ :
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In like manner, steam is extracted from a .
third predetermined extraction zone 78 within the low pressure turbine 20 and conducted through conduits 80 into : .
' the third reheater 62, this flow being illustrated by :.
reference arrows 82. As is apparent, each of the extraction zones66, 72 and 78 extracts steam from within the turbine 20 at a higher te-mperature and pressure condition, and thus the steam so extracted has associated therewith an ~-~ increasingly higher heat capacity. In order to fully lO utilize the heat content of the extracted steam, the :
drains of the reheaters 62, 60 and 58 are cascaded into each other, as illustrated by flow arrows 84 and 86. The ;-drain from the reheater 58 is conducted, as shown by arrow ~ .
88, into the condenser 22. Some plants provide, intermediate .
between the condensate pump 56 and the first feedwater ~:
heater 58, a condenser which returns gland sealing steam .
. to the liquid state. The drain from the gland condenser, .l although omitted for clarity, enters into the main `~ condenser at a point intermediate between the drain of the .
l 20 feedwater heater 58 and the condenser 22. -:! :
As seen from the figure, the heater 64 derives ;:
, its heat from steam extracted from a predetermined .l extraction zone 90 within the high pressure turbine 18, through conduits 92, the flow being illustrated by flow arrows 94.
.~ A boiler feed pump 96 is located downstream of l the heater 64 and`pumps the nloOw-heated condensate through :
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45~890 ; '~ ~'.' '', ' ~',' ' ~0 4Z~9 a final feedwater heater 98~ From the final feedwater heater 98 ~ the condensate, now known as boiler feedwater, ~:
.- :
is conducted to the s-team generator 16 to complete the steam power plant loop 10, the flow being illustrated by .
reference arrow 100. The final feedwater heater 98 utilizes steam extracted from a second predetermined ~ :
i, . -extraction zone 102 located within the high pressure .:.... :
. turbine 18~ the steam being conducted through conduits .
` 104 ~ as shown by flow arrows 106 ~ As seen from the figure, ~
10 the second predetermined extraction zone 102 occurs at a ~ : :
location within the high pressure turbine 18 that has ~-associated with it a greater heat capacity than does the ~. .
steam from extraction zone 90. In order to efficiently ~ ~ :
; extract all available energy from the higher heat capacity steam, the drain of the final feedwater heater 98 is cascaded, as shown by arrow 108~ into the heater 64~ The ~.
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draln from the heater 64 is itself pumped by a drain pump `~
.j (not shown) lnto the condensate flow to a point (not shown) -, lmmediately upstream o~ the boiler feed pump 96~ For .. ~
; 20 completeness, the drain from the moisture separator .. ;
.~ por-tion of the MS-R 40 also is collected and pumped by ~ .
the drain pump (not shown) to the point (not shown) ~ immediately upstream of the boiler feed pump 96~ Also :
;~y omitted from the figure for clarity is the connection , :
. between the drain of the reheater portion of the MS-R 40 . and the final feedwater heater 98 :~ In order to provide motive power for the boiler . ~eed pump 96 ~ there is provided a boiler feed pump drive ;l turbine 110, which is linked mechanically by a shaft 112
3 to the boiler feed pump 96~ The motive fluid for the .'` `'` '' ' . ':, .
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drive turbine 110 is often prcvided by a tap immediately downstream o~ the MS-R 40, the flow being illustrated by arrow 114. It should be understood that similar drive turbines or other mechanical linkages are disposed to provide motive energy for other apparatus associated with the power plant 10, of which the feed pump 96 is , illustrative. For example, power must be provided to the ,~ :
condensate pump 56 and air ejectors. Although such linkages are omitted for clarity, it is to be understood that there exist drive turbines or drive motors, such as that shown at 110, to provide power to these associated apparatus. The exhaust fromthe drive turbine 110 is ; conducted, in a normal power plant, through conduit 116 ~¦
to the condenser 22. However, in accordance with this inventlon, a control valve 118, normally closed, is provided between the conduit 116 and condenser 22. In a manner which is more fully explalned herein, the exhaust rom the drive turbine 110~ or other power sources for the steam æystems associated apparatus, is conducted by conduit 120 into, and acts as a one of the heat sources for, the separate heat cycle 12 taught by this invention.
It is also known in the art that the control of ' -;
the flow of condensate in that portion of the power plant 10 between the condensate pump 56 and the boiler ~eed pump 96 is managed by a suitable control arrangement ~ (not shown). It is to be understood, however, that there ',3l -is a predetermined flow rate associated with the condensate flow within the plant 10.
Cooperatively associated with the power plant 10 is the heat transfer cycle 12. As stated earlier, the :
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steam power plant 10 is a standard power generation facility. All elements contained therein are sized and ;~ designed such that high efficiency and maximum electrical j generating capability is maintained. The heat transfer cycle 12 is a closed loop arrangement cooperatively ; associated with the steam plant 10 to extract heat there~
from and supply the heat so extracted to the external heat ~
load 13. Although this application will discuss the heat ~--` load in terms of brine heati~g for a water desalinization plant to provide fresh water, it is to be understood that ;t any heat load, such as industrial or residential heating, , may be supplied.
`~ The heat cycle 12 typically comprises heater elements 122, 124, 126, 128, 130 and 132 disposed so as to ;: .: ' ' extract heat from the power plant 10 and transfer that heat 'i .. ,. :.. .,.:. to a heat transfer medium~ such as, but not limited to, ' water under a predetermined pressure, flowing within the closed loop flow arrangement 12, The extracted heat carried by the heat transfer medium is exchanged in a heat exchanger element 134, in this instance a brine heater, and supplied to the heat load 13. Completing the closed -~
loop arrangement 12 is a flow control valve 136 and a -~
, variable speed pump 138, similar to the condensate pump 56, to control the flow rate of the heat transfer medium, the flow direction being indicated by arrow 140. If ' necessary, a surge tank 142 may be added to the arrangement.
The heat transferred by the heaters to the heat '~
transfer medium is obtained by extraction of steam from ; -.~
: predetermined locati~ns within the power plant 10. The `
~`~ 30 steam extraction locations for each particular heater will ' .
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be discussed in turn.
The heacer 122 obtains steam exhausted from the drive turbine 110 powering the associated steam apparatus, such as the boiler feed pump 96, through conduits 116 and 120. The pressure of the steam so extracted, typically, approximates that of the lowe~t pressure feedwater heater 58. In the case of no water demand, of course, the valve 118 is opened, to permit~
exhaust directly to the condenser 22. ;-As seen from the figure, heaters 124 and 126 extract heat from the plant 10 through the extraction of steam from predetermined locations within the low pressure turbines 20. For example, heater 124 is supplied by a i conduit 144 tapping into the conduit 68 and extracting ..
steam from steam extraction zone 66, this flow being illustrated by arrow 146. Heater 126, ln similar manner, is connected through a conduit 148 which taps into the conduit 74 to extract steam from the extraction zone 72 within the low pressure turbine 20, this flow illustrated ~
by arrow 150. ~ -Heaters 128 and 130 are, as shown, supplied with extraction steam from extraction zones 90 and 102 respec-tively, within the high pressure turbine 18. In the case of the heater 128, a conduit 152 taps into the conduit 92 to extract steam from zone 90, the exhaust of the high pressure turbine 18, that flow being illustrated by arrow 154. For theheater 130, the conduit 104 from zone 102 is tapped by conduit 155, the flow being illustrated by arrow 156.
The steam source for the heater 132 is a tap 158 .
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immediately past the outlet of the steam generator 16, a bypass conduit 160 having a normally closed control valve ;~
162 disposed therein regulating the flow, as illustrated by flow arrow 164. As will be discussed herein, the provision of the bypass conduit 160 enables the heat cycle 12 associated with the power plant 10 to be operable even during periods of zero electrical power generation, during periods of low electrical loads or during periods of peak water demand.
, 10 Normally, however, the control valve 162 is closed, but extraction of steam from the other sources, as outlined, provides the sufficient heat necessary to -produce desalinization. It is apparent from examination of the figure that the cycle 12 extracts steam from several distinct locations within the plant 10, each of which has associated therewith a separate heating capacity.
By heating capacity lt is meant the heat content, or ~-enthalpy, associated wlth the steam at the particular temperature and pressure at which that steam is taken from the plant 10. For example~ it is clear that steam extracted to the heater 130 from the extraction zone 102 within the high pressure burbine 18 has a greater heating capacity than steam extracted to the heater 124 from the t!~ ~ 'I '.
extraction zone 66 within the low pressure turbine 20.
By providing a closed loop 12 able to take heat from a predetermined plurality of locations within the power -plant 10, sufficient heat may be provided for a large-scale :, .
` desalinization project without overly taxing any single ;
`~, heat source location. Provision of the closed loop 12 , . . . .
enables maximum heat transfer to occur from the steam cycle -~
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10 to the heat transfer cycle 12 while still permitting -utilization of standard components within the steam plant.
Of course, in order to enhance the efficiency of the cycle 12, the drain from each higher pressure heater is cascaded into the next lower pressure heater, as illustrated by arrows 168, 170, 172, 174 and 176. The drains of the lowest pressure heater 122 in the heat -~
cycle 12 is returned, as shown by the ~low arrow 180, to the condenser 22.
The flow rate of the heat transfer medium within i -f the closed loop heat transfer cycle 12 is controlled, as stated, by the pump 138 in association with the valve 136.
The flow rate is related to the rate of main condensate flow between the pumps 56 and 96 which is part of the overall motive ~luid flow rate of the power plant 18. The heat transfer medium flow rate is between 0 to .8 of the maln condensate flow rate, the exact value of heat transfer medium flow rate being determined by a suitable control arrangement 170 associated with the overall power plant control (not shown) and being functionally related to the demand required by the desalinizer.
, In operation, then, for a given heat demand, the , heat transfer medium passes within the closed-loop cycle 12 at a predetermined flow rate between 0 and .8 of the main condensate flow rate. The heat transfer medium is heated by passage through the heater 122 supplied ~rom the exhaust of the drive turbine 110, through the heaters 124 and 126 supplied with heat by extraction from the low pressure turbine 20, and through the heaters 128 and 130 ;:
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supplied by steam extracted from the high pressure turbine 18. If necessary, the medium is further heated by the heater 132 supplied with steam through the bypass conduit 160 from the steam generator 16. The heat so .
extracted is transferred from the heat transfer medium to the brine within the heat exchanger 134. The steam extracted from the plant 10 is returned ta the condenser 22, after cascading through the lower pressure heaters. i~-As may be appreciated by one skilled in the art, the volume of the steam extracted from the power plant 10, ;
and thus the magnitude of heat extracted therefrom, is -: . . .:
directly related to the ~low rate o~ the heat transfer -medium. For example, attention is directed to the heater ~;
126, supplied with steam extracted from the extraction zones 72 within the low pressure turbines 20. The steam so extracted has associated therewith a predetermined `
pressure, for example approximately 25 p~s.i,a. and an associated temperature, here, 240F, When such steam is conducted into the shell of the reheater 126, it condenses on the tubes passing therethrough and having the heat transfer medium therein. The heat transfer medium takes ` the heat of vaporization from the extracted steam at the ~`
given pressure, and temperature, here 240F, and the heat-transfer medium is heated thereby. As the heat of vapor-ization is taken by the heat transfer medium, the extracted steam condenses, and more steam is drawn into the heater from the extraction zone. However, it is apparent that the temperature of the heat transfer medium may only rise ;
to the saturation temperature associated with the pressure of the extracted steam, in this instance, to 240F. Once :. --17-- :`
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Z9~ ' the heat transfer medium is heated by the extraction steam to this temperature, that medium takes no additional heat ;~
from the extracted steam. With this occurrence, no further extracted steam condenses in the heater 126, and no further steam is extracted from the zone 72 to the heater 126. Thus, the volume of steam extracted is auto-matically limited by a thermodynamic equilibrium established within the heater 126, This process is similar to that occurring in all the heaters within the closed loop heat transfer cycle 12, no matter what the location of ' the heat source supplying the heater.
To further increase the volume of steam extracted, it is simply necessary to increase the flow rate of the heat transfer medium. Since more of the medium will pass through the heater 126, more medium will be available to take the heat o~ condensation from the extracted steam. There~ore, more of the extracted steam condenses within the heater 126, and therefore more steam is extracted from the turbine 20. Conversely, o~ course, to decrease the amount o~ steam extracted from the plant 10, the simple expedient o~ lowering the ~low rate of the ~ -heat transfer medium accomplishes this result. In the ~ extreme case, i.e., when the water demand is zero, no ; steam will be extracted if the heat transfer medium flow .,. . ~:
is stopped. As stated, then, by varying the flow-rate of the heat transfer medium between 0 and .8 of the predetermined ~low rate of the main condensate flow, the volume of steam extracted from the power plant is directly controllable. Of course, any known expedient for ; 30 controlling the flow rate of the heat transfer medium is :, .
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within the contemplation of this invention. The flow rate of the heat transfer medium is controlled so as to maintain steam extraction from the various heat source locations within allowable design capabilities of a power generation cycle utilizing standard turbine ~ ;
elements.
If the electrical load condition on the power plant 10 were to be reduced by a given amount, the flow rate of the motive fluid through the power generation cycle, which includes the condensate flow, is commensurately reduced. If the flow rate of the heat transfer medium was not correspondingly adjusted, the heaters within the .: . .
heat transfer cycle 12 would extract, from the heat source `
locations within the power plant lO, volumetric flows of -steam greater than those optimumly permitted by standard `
system components. Therefore, it is appreciated that the flow rate of the heat transfer medium is functionally ~;
. .
related to the flow rate of the main condensate flow, with the heat transfer flow rate being at all times within the ~ -limits 0 to .8 of the main condensate flow rate.
During periods of low electrical loads, then, , . ...
the motive fluid flow requirements of the power generation cycle 10 are lower, necessarily resulting in a lower heat ;
:;
transfer medium flow rate, If, however, at this same time there is imposed upon the heat transfer cycle 12 an increase in the heat load, this increase may be met by simply opening the control valve 162 to initiate flow from the steam generator 16 to the heater 132.
It is appreciated then that the closed loop .,. ~ ,.
~ 30 heat transfer cycle 12 associated with the power plant :. `.: --19--~,. .
.,.,' .
45,890 ,--)4 10 admirably accomplishes all those functions unable to be effected by prior art systems~ There is provided an overall system for the supply of heat to a desalinization plant, or other heat load, which utilizes proven, standardized turbine-generator component designs. By provision of the closed-loop cycle, heat is extracted . from a predetermined plurality of locations within the - power plant, thus no one location is overtaxed for extraction steam, thus guaranteeing maximum heat transfer capability while maintaining the capability for generation of large amounts of electrical power with standard components. There is also provided full capability for power during peak electrical periods. By closing the . valve 162 in the bypass conduit 160, and reducing the heat transfer medium flow rate to zero, full rated electrical power may be generated.
~ Provision is also made for the production simul-i; taneously of both electricity and water, during periods of moderate electrical and moderate water demand. Pertur-bations in water demand may be accommodated, for example, by varying the heat-transfer flow rate, by opening the control valve 162, or by using the valve 162 to modulate an already established bypass flow. The ratio of electrical , output to heat output may thus be varied on command. A
switch-back capability between electricity and water demands may also be easily accommodated.
The system embodying the teachings of this invention also provides for water production during periods of no electrical demand, or during periods of turbine unavailabil-ity. By providing the closed loop cycle, the heat demand ~ . .
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is no longer tied to the actual operation of the power ~-generating ~acility. Conversely, needed turbine main-tenance or inspection need not be dependent upon periods of slack water demand. Implicit to this consideration is the ability to provide water during off-peak electrical periods while still maintaining peak electrical capability on demand.
It being understood that although a specific - ,~
preferred embodiment of the invention has been shown and described, modifications may be made without departing from the spirit of the invention, as embodied in the appended claims.
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drive turbine 110 is often prcvided by a tap immediately downstream o~ the MS-R 40, the flow being illustrated by arrow 114. It should be understood that similar drive turbines or other mechanical linkages are disposed to provide motive energy for other apparatus associated with the power plant 10, of which the feed pump 96 is , illustrative. For example, power must be provided to the ,~ :
condensate pump 56 and air ejectors. Although such linkages are omitted for clarity, it is to be understood that there exist drive turbines or drive motors, such as that shown at 110, to provide power to these associated apparatus. The exhaust fromthe drive turbine 110 is ; conducted, in a normal power plant, through conduit 116 ~¦
to the condenser 22. However, in accordance with this inventlon, a control valve 118, normally closed, is provided between the conduit 116 and condenser 22. In a manner which is more fully explalned herein, the exhaust rom the drive turbine 110~ or other power sources for the steam æystems associated apparatus, is conducted by conduit 120 into, and acts as a one of the heat sources for, the separate heat cycle 12 taught by this invention.
It is also known in the art that the control of ' -;
the flow of condensate in that portion of the power plant 10 between the condensate pump 56 and the boiler ~eed pump 96 is managed by a suitable control arrangement ~ (not shown). It is to be understood, however, that there ',3l -is a predetermined flow rate associated with the condensate flow within the plant 10.
Cooperatively associated with the power plant 10 is the heat transfer cycle 12. As stated earlier, the :
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steam power plant 10 is a standard power generation facility. All elements contained therein are sized and ;~ designed such that high efficiency and maximum electrical j generating capability is maintained. The heat transfer cycle 12 is a closed loop arrangement cooperatively ; associated with the steam plant 10 to extract heat there~
from and supply the heat so extracted to the external heat ~
load 13. Although this application will discuss the heat ~--` load in terms of brine heati~g for a water desalinization plant to provide fresh water, it is to be understood that ;t any heat load, such as industrial or residential heating, , may be supplied.
`~ The heat cycle 12 typically comprises heater elements 122, 124, 126, 128, 130 and 132 disposed so as to ;: .: ' ' extract heat from the power plant 10 and transfer that heat 'i .. ,. :.. .,.:. to a heat transfer medium~ such as, but not limited to, ' water under a predetermined pressure, flowing within the closed loop flow arrangement 12, The extracted heat carried by the heat transfer medium is exchanged in a heat exchanger element 134, in this instance a brine heater, and supplied to the heat load 13. Completing the closed -~
loop arrangement 12 is a flow control valve 136 and a -~
, variable speed pump 138, similar to the condensate pump 56, to control the flow rate of the heat transfer medium, the flow direction being indicated by arrow 140. If ' necessary, a surge tank 142 may be added to the arrangement.
The heat transferred by the heaters to the heat '~
transfer medium is obtained by extraction of steam from ; -.~
: predetermined locati~ns within the power plant 10. The `
~`~ 30 steam extraction locations for each particular heater will ' .
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be discussed in turn.
The heacer 122 obtains steam exhausted from the drive turbine 110 powering the associated steam apparatus, such as the boiler feed pump 96, through conduits 116 and 120. The pressure of the steam so extracted, typically, approximates that of the lowe~t pressure feedwater heater 58. In the case of no water demand, of course, the valve 118 is opened, to permit~
exhaust directly to the condenser 22. ;-As seen from the figure, heaters 124 and 126 extract heat from the plant 10 through the extraction of steam from predetermined locations within the low pressure turbines 20. For example, heater 124 is supplied by a i conduit 144 tapping into the conduit 68 and extracting ..
steam from steam extraction zone 66, this flow being illustrated by arrow 146. Heater 126, ln similar manner, is connected through a conduit 148 which taps into the conduit 74 to extract steam from the extraction zone 72 within the low pressure turbine 20, this flow illustrated ~
by arrow 150. ~ -Heaters 128 and 130 are, as shown, supplied with extraction steam from extraction zones 90 and 102 respec-tively, within the high pressure turbine 18. In the case of the heater 128, a conduit 152 taps into the conduit 92 to extract steam from zone 90, the exhaust of the high pressure turbine 18, that flow being illustrated by arrow 154. For theheater 130, the conduit 104 from zone 102 is tapped by conduit 155, the flow being illustrated by arrow 156.
The steam source for the heater 132 is a tap 158 .
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immediately past the outlet of the steam generator 16, a bypass conduit 160 having a normally closed control valve ;~
162 disposed therein regulating the flow, as illustrated by flow arrow 164. As will be discussed herein, the provision of the bypass conduit 160 enables the heat cycle 12 associated with the power plant 10 to be operable even during periods of zero electrical power generation, during periods of low electrical loads or during periods of peak water demand.
, 10 Normally, however, the control valve 162 is closed, but extraction of steam from the other sources, as outlined, provides the sufficient heat necessary to -produce desalinization. It is apparent from examination of the figure that the cycle 12 extracts steam from several distinct locations within the plant 10, each of which has associated therewith a separate heating capacity.
By heating capacity lt is meant the heat content, or ~-enthalpy, associated wlth the steam at the particular temperature and pressure at which that steam is taken from the plant 10. For example~ it is clear that steam extracted to the heater 130 from the extraction zone 102 within the high pressure burbine 18 has a greater heating capacity than steam extracted to the heater 124 from the t!~ ~ 'I '.
extraction zone 66 within the low pressure turbine 20.
By providing a closed loop 12 able to take heat from a predetermined plurality of locations within the power -plant 10, sufficient heat may be provided for a large-scale :, .
` desalinization project without overly taxing any single ;
`~, heat source location. Provision of the closed loop 12 , . . . .
enables maximum heat transfer to occur from the steam cycle -~
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10 to the heat transfer cycle 12 while still permitting -utilization of standard components within the steam plant.
Of course, in order to enhance the efficiency of the cycle 12, the drain from each higher pressure heater is cascaded into the next lower pressure heater, as illustrated by arrows 168, 170, 172, 174 and 176. The drains of the lowest pressure heater 122 in the heat -~
cycle 12 is returned, as shown by the ~low arrow 180, to the condenser 22.
The flow rate of the heat transfer medium within i -f the closed loop heat transfer cycle 12 is controlled, as stated, by the pump 138 in association with the valve 136.
The flow rate is related to the rate of main condensate flow between the pumps 56 and 96 which is part of the overall motive ~luid flow rate of the power plant 18. The heat transfer medium flow rate is between 0 to .8 of the maln condensate flow rate, the exact value of heat transfer medium flow rate being determined by a suitable control arrangement 170 associated with the overall power plant control (not shown) and being functionally related to the demand required by the desalinizer.
, In operation, then, for a given heat demand, the , heat transfer medium passes within the closed-loop cycle 12 at a predetermined flow rate between 0 and .8 of the main condensate flow rate. The heat transfer medium is heated by passage through the heater 122 supplied ~rom the exhaust of the drive turbine 110, through the heaters 124 and 126 supplied with heat by extraction from the low pressure turbine 20, and through the heaters 128 and 130 ;:
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supplied by steam extracted from the high pressure turbine 18. If necessary, the medium is further heated by the heater 132 supplied with steam through the bypass conduit 160 from the steam generator 16. The heat so .
extracted is transferred from the heat transfer medium to the brine within the heat exchanger 134. The steam extracted from the plant 10 is returned ta the condenser 22, after cascading through the lower pressure heaters. i~-As may be appreciated by one skilled in the art, the volume of the steam extracted from the power plant 10, ;
and thus the magnitude of heat extracted therefrom, is -: . . .:
directly related to the ~low rate o~ the heat transfer -medium. For example, attention is directed to the heater ~;
126, supplied with steam extracted from the extraction zones 72 within the low pressure turbines 20. The steam so extracted has associated therewith a predetermined `
pressure, for example approximately 25 p~s.i,a. and an associated temperature, here, 240F, When such steam is conducted into the shell of the reheater 126, it condenses on the tubes passing therethrough and having the heat transfer medium therein. The heat transfer medium takes ` the heat of vaporization from the extracted steam at the ~`
given pressure, and temperature, here 240F, and the heat-transfer medium is heated thereby. As the heat of vapor-ization is taken by the heat transfer medium, the extracted steam condenses, and more steam is drawn into the heater from the extraction zone. However, it is apparent that the temperature of the heat transfer medium may only rise ;
to the saturation temperature associated with the pressure of the extracted steam, in this instance, to 240F. Once :. --17-- :`
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Z9~ ' the heat transfer medium is heated by the extraction steam to this temperature, that medium takes no additional heat ;~
from the extracted steam. With this occurrence, no further extracted steam condenses in the heater 126, and no further steam is extracted from the zone 72 to the heater 126. Thus, the volume of steam extracted is auto-matically limited by a thermodynamic equilibrium established within the heater 126, This process is similar to that occurring in all the heaters within the closed loop heat transfer cycle 12, no matter what the location of ' the heat source supplying the heater.
To further increase the volume of steam extracted, it is simply necessary to increase the flow rate of the heat transfer medium. Since more of the medium will pass through the heater 126, more medium will be available to take the heat o~ condensation from the extracted steam. There~ore, more of the extracted steam condenses within the heater 126, and therefore more steam is extracted from the turbine 20. Conversely, o~ course, to decrease the amount o~ steam extracted from the plant 10, the simple expedient o~ lowering the ~low rate of the ~ -heat transfer medium accomplishes this result. In the ~ extreme case, i.e., when the water demand is zero, no ; steam will be extracted if the heat transfer medium flow .,. . ~:
is stopped. As stated, then, by varying the flow-rate of the heat transfer medium between 0 and .8 of the predetermined ~low rate of the main condensate flow, the volume of steam extracted from the power plant is directly controllable. Of course, any known expedient for ; 30 controlling the flow rate of the heat transfer medium is :, .
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within the contemplation of this invention. The flow rate of the heat transfer medium is controlled so as to maintain steam extraction from the various heat source locations within allowable design capabilities of a power generation cycle utilizing standard turbine ~ ;
elements.
If the electrical load condition on the power plant 10 were to be reduced by a given amount, the flow rate of the motive fluid through the power generation cycle, which includes the condensate flow, is commensurately reduced. If the flow rate of the heat transfer medium was not correspondingly adjusted, the heaters within the .: . .
heat transfer cycle 12 would extract, from the heat source `
locations within the power plant lO, volumetric flows of -steam greater than those optimumly permitted by standard `
system components. Therefore, it is appreciated that the flow rate of the heat transfer medium is functionally ~;
. .
related to the flow rate of the main condensate flow, with the heat transfer flow rate being at all times within the ~ -limits 0 to .8 of the main condensate flow rate.
During periods of low electrical loads, then, , . ...
the motive fluid flow requirements of the power generation cycle 10 are lower, necessarily resulting in a lower heat ;
:;
transfer medium flow rate, If, however, at this same time there is imposed upon the heat transfer cycle 12 an increase in the heat load, this increase may be met by simply opening the control valve 162 to initiate flow from the steam generator 16 to the heater 132.
It is appreciated then that the closed loop .,. ~ ,.
~ 30 heat transfer cycle 12 associated with the power plant :. `.: --19--~,. .
.,.,' .
45,890 ,--)4 10 admirably accomplishes all those functions unable to be effected by prior art systems~ There is provided an overall system for the supply of heat to a desalinization plant, or other heat load, which utilizes proven, standardized turbine-generator component designs. By provision of the closed-loop cycle, heat is extracted . from a predetermined plurality of locations within the - power plant, thus no one location is overtaxed for extraction steam, thus guaranteeing maximum heat transfer capability while maintaining the capability for generation of large amounts of electrical power with standard components. There is also provided full capability for power during peak electrical periods. By closing the . valve 162 in the bypass conduit 160, and reducing the heat transfer medium flow rate to zero, full rated electrical power may be generated.
~ Provision is also made for the production simul-i; taneously of both electricity and water, during periods of moderate electrical and moderate water demand. Pertur-bations in water demand may be accommodated, for example, by varying the heat-transfer flow rate, by opening the control valve 162, or by using the valve 162 to modulate an already established bypass flow. The ratio of electrical , output to heat output may thus be varied on command. A
switch-back capability between electricity and water demands may also be easily accommodated.
The system embodying the teachings of this invention also provides for water production during periods of no electrical demand, or during periods of turbine unavailabil-ity. By providing the closed loop cycle, the heat demand ~ . .
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is no longer tied to the actual operation of the power ~-generating ~acility. Conversely, needed turbine main-tenance or inspection need not be dependent upon periods of slack water demand. Implicit to this consideration is the ability to provide water during off-peak electrical periods while still maintaining peak electrical capability on demand.
It being understood that although a specific - ,~
preferred embodiment of the invention has been shown and described, modifications may be made without departing from the spirit of the invention, as embodied in the appended claims.
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Claims (8)
1. A steam turbine power plant comprising, in series, a steam generator element, a high pressure turbine element, a low pressure turbine element, a condenser element, a high pressure feedwater heater extracting steam from a predetermined location within said high pressure turbine element, a low pressure feedwater heater extracting steam from a predetermined location within said low pressure turbine element, said steam extracted from said high pressure turbine having associated therewith a heating capacity different from the heating capacity of said steam extracted from said low pressure turbine element, a closed loop flow arrangement disposed only in heat transfer relationship with said power plant to extract heat therefrom to supply a heat load, said flow arrangement confining and guiding a heat transfer medium therewithin, a first and a second heater element connected within said flow arrangement, said first heater element extracting heat from said power plant by extracting steam from said predetermined location within said low pressure turbine element and disposed in parallel with said low pressure feedwater heater, said second heater element extracting heat from said power plant by extracting steam from said predetermined location within said high pressure turbine element and disposed in parallel with said high pressure feedwater heater, said heater elements transferring said extracted heat to said heat transfer medium, a heat exchange element connected within said flow arrangement for exchanging said extracted heat in said heat transfer medium to said heat load, and, means for controlling the rate of flow of said heat transfer medium within said closed loop flow arrange-ment, the magnitude of said heat extracted from said power plant being directly controlled by said flow rate of said heat transfer medium.
2. The power plant of claim 1, further comprising:
a third heater element connected within said flow arrangement, said third heater element extracting heat from a third location within said power plant and transferring said extracted heat to said heat transfer medium, said third location being disposed away from said first and said second locations and having a heating capacity associated therewith different from said heating capacities associated with said first and second locations, the magnitude of said heat extracted from said third location within said power plant being directly con-trolled by said flow rate of said heat transfer medium within said closed loop flow arrangement.
a third heater element connected within said flow arrangement, said third heater element extracting heat from a third location within said power plant and transferring said extracted heat to said heat transfer medium, said third location being disposed away from said first and said second locations and having a heating capacity associated therewith different from said heating capacities associated with said first and second locations, the magnitude of said heat extracted from said third location within said power plant being directly con-trolled by said flow rate of said heat transfer medium within said closed loop flow arrangement.
3. The power plant of claim 2 wherein said third location is disposed intermediate between said steam generator element and said high pressure turbine element.
4. The power plant of claim 3, further comprising:
flow interruption means for interrupting steam flow disposed between said third heater element and said ex-traction point intermediate said steam generator element and said high pressure turbine element.
flow interruption means for interrupting steam flow disposed between said third heater element and said ex-traction point intermediate said steam generator element and said high pressure turbine element.
5. The power plant of claim 3, further comprising:
an associated apparatus connected in series within said power plant, said associated apparatus being driven by a drive turbine element operatively connected within said power plant, a fourth heater element connected within said flow arrangement at a point upstream of said first heater element, said fourth heater element extracting heat from said power plant and transferring said extracted heat to said heat trans-fer medium, said fourth heater element extracting heat from said power plant by extracing steam from said drive turbine element, the heating capacity associated with said steam extracted from said drive turbine element being different from the heating capacity associated with said steam extracted by said first, second, and third heater elements, the amount of said steam extracted from said drive turbine element being directly controlled by said flow rate of said heat transfer medium within said closed loop flow arrangement.
an associated apparatus connected in series within said power plant, said associated apparatus being driven by a drive turbine element operatively connected within said power plant, a fourth heater element connected within said flow arrangement at a point upstream of said first heater element, said fourth heater element extracting heat from said power plant and transferring said extracted heat to said heat trans-fer medium, said fourth heater element extracting heat from said power plant by extracing steam from said drive turbine element, the heating capacity associated with said steam extracted from said drive turbine element being different from the heating capacity associated with said steam extracted by said first, second, and third heater elements, the amount of said steam extracted from said drive turbine element being directly controlled by said flow rate of said heat transfer medium within said closed loop flow arrangement.
6. The power plant of claim 5, further comprising:
a fifth heater element connected within said flow arrangement at a point intermediate said first and said second heater elements, said fifth heater element extracting heat from said power plant and transferring said extracted heat to said heat transfer medium, said fifth heater element extracting heat from said power plant by extracting steam from a second extrac-tion point within said low pressure turbine element, the heating capacity of said steam extracted from said second extraction point within said low pressure turbine element being greater than the heating capacity of said steam extracted from said first extraction point within said low pressure turbine element, the amount of said steam extracted from said second extraction point within said low pressure turbine element being directly controlled by said flow rate of said heat transfer medium within said closed loop flow arrangement.
a fifth heater element connected within said flow arrangement at a point intermediate said first and said second heater elements, said fifth heater element extracting heat from said power plant and transferring said extracted heat to said heat transfer medium, said fifth heater element extracting heat from said power plant by extracting steam from a second extrac-tion point within said low pressure turbine element, the heating capacity of said steam extracted from said second extraction point within said low pressure turbine element being greater than the heating capacity of said steam extracted from said first extraction point within said low pressure turbine element, the amount of said steam extracted from said second extraction point within said low pressure turbine element being directly controlled by said flow rate of said heat transfer medium within said closed loop flow arrangement.
7. The power plant of claim 6, further comprising:
a sixth heater element connected within said flow arrangement at a point intermediate said second and said third heater elements, said sixth heater element extracting heat from said power plant and transferring said extracted heat to said heat transfer medium, said sixth heater element extracting heat from said power plant by extracting steam from a second extraction point within said high pressure turbine element, the heating capacity of said steam extracted from said second extraction point within said high pressure tur-bine element being greater than the heating capacity of said steam extracted from said first extraction point within said high pressure turbine element, the amount of said steam extracted from said second extraction point within said high pressure turbine element being directly controlled by said flow rate of said heat transfer medium within said closed loop flow arrangement.
a sixth heater element connected within said flow arrangement at a point intermediate said second and said third heater elements, said sixth heater element extracting heat from said power plant and transferring said extracted heat to said heat transfer medium, said sixth heater element extracting heat from said power plant by extracting steam from a second extraction point within said high pressure turbine element, the heating capacity of said steam extracted from said second extraction point within said high pressure tur-bine element being greater than the heating capacity of said steam extracted from said first extraction point within said high pressure turbine element, the amount of said steam extracted from said second extraction point within said high pressure turbine element being directly controlled by said flow rate of said heat transfer medium within said closed loop flow arrangement.
8. The power plant of claim 2, wherein said steam produced by said steam generator element is condensed by said condenser element and is returned in liquid form to said steam generator element, the flow of said liquid from said condenser element to said steam generator element having a predetermined flow rate associated therewith, and, said means for controlling the rate of flow of said heat transfer medium being functionally related to and variable in a range of values between zero and .8 of said predetermined flow rate of said liquid.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US54871075A | 1975-02-10 | 1975-02-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1042290A true CA1042290A (en) | 1978-11-14 |
Family
ID=24190077
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA243,699A Expired CA1042290A (en) | 1975-02-10 | 1976-01-16 | Turbine generator cycle for provision of heat to an external heat load |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS5199748A (en) |
| CA (1) | CA1042290A (en) |
| ES (1) | ES444506A1 (en) |
| IL (1) | IL48723A (en) |
| IT (1) | IT1055168B (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5230655B2 (en) * | 1971-11-29 | 1977-08-09 | ||
| JPS491927A (en) * | 1972-04-26 | 1974-01-09 |
-
1975
- 1975-12-24 IL IL48723A patent/IL48723A/en unknown
-
1976
- 1976-01-16 CA CA243,699A patent/CA1042290A/en not_active Expired
- 1976-01-21 ES ES444506A patent/ES444506A1/en not_active Expired
- 1976-01-27 JP JP723076A patent/JPS5199748A/en active Pending
- 1976-02-10 IT IT2002276A patent/IT1055168B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5199748A (en) | 1976-09-02 |
| ES444506A1 (en) | 1977-05-16 |
| IT1055168B (en) | 1981-12-21 |
| IL48723A (en) | 1977-12-30 |
| IL48723A0 (en) | 1976-02-29 |
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