US1846047A

US1846047A - Evaporator system

Info

Publication number: US1846047A
Application number: US30194A
Authority: US
Inventors: Brown Stanley
Original assignee: Griscom Russell Co
Current assignee: Griscom Russell Co
Priority date: 1925-05-14
Filing date: 1925-05-14
Publication date: 1932-02-23
Anticipated expiration: 1949-02-23

Description

Feb. 23, 1932. 5. BROWN EVAPORATOR SYSTEM Filed May 14, 1925 2 Sheets-Sheet IN VEN TOR 5 iii .I' j w r 4 4 g 4 ww 11! 4 JMm l 0 Z a E 5 9 J m 5 A q a a m mw M 4 T 36 a m 5 r a T 6 w B X A [W u u v R HT 4n ELEEDER TURBINE TURBINE EXHAUST 1 BY M an) %W, %WA

A TTORNE Y Patented Feb. 23, 1932 UNITED STATES PATENT OFFICE STANLEY BROWN, 0]! GARDEN CITY, NEW YORK, ASSIGNOB TO THE GBISGOH RUSSELL COMPANY, OF NEW YORK, N. Y.,

A CORPORATION OF DELAWARE EVAPORATOR SYSTEM Application filed Kay 14,

The present invention relates to steam power systems applicable to central stations, industrial plants, marine installations, or the like, wherever steam for power is to used in considerable quantities, and has to do particularly with a method of lIIt-I'OdllOlllg into such a system an evaporator unit for the purpose of supplying purified boiler feed make up to the system.

In modern steam systemsmuch attention has been given to the efiicient utilization of the various returns from the auxiliary apparatus and other steam utilizing units of the system. The available heat in the various returns is usually transferred insofar as 1s possible to the boiler feed water and thus serves to preheat the water before admission to the main boilers. Frequentl the steam available for preheating the boi er' feed occurs at two or more different conditions of pressure and temperature, and accordingly it has been proposed to transfer independently to the boiler feed water the heat from these various sources of steam at substantially the respective pressures and temperatures of the steam sources. A plant laid out along these lines comprises two or more heat transtel-ring elements operating-at diflerent pressures, the boiler feed water passing successively through these heaters as condensers from the lowest pressure to the highest. The circuit between the steam generating system and the steam 'utilizing apparatus of the plant is a closed circuit and it is the intent of such a system to repeatedly return to the boiler all of the fluid medium which is sup plied to the steam utilizing apparatus of the plant. There are, however, certain unavoidable losses due to leakage and the like, and these losses must be made up by supplying to the boiler a corresponding additional quantity of feed. This purified make up water is commonly derived from one or more evaporators employed to distill over the raw water supplied to the system in order that the make up as conducted into the boilers will be substantially free from scale forming impurities. The available heat in the vapor output and the drains from the heating coils of 1925. Serial No. 30,194.

the evaporator should, of course, be accommodated in the system. v

Many of the latest steam power stations are equipped with so-called bleeder turbines, which turbines are equipped to deliver at two or more stages partially used steam for the purpose of heating the boiler feed water at successive steps at the proper ressure and temperature conditions. The b eder type turbine is commonly the principal 4 power developing unit of the plant and receives its steam supply at a relatively high initial pressure. The turbine is so designed as to operate most efficiently when a certain amount of steam-is tapped off or bled from certain designated stages of the turbine. In case the steam taken from any bleeder stage of the turbine is materially lesser or ater in amount than that for which the tur ine is .designed, a corresponding loss in power will be experienced. Forinstance, if say from one of the higher pressure stages of the turbine an insufficient amount of bleeden steam' is withdrawn the portion which should have been withdrawn passes on through the next lower stages of the turbine and of course gives up a certain increment of power to the turbine wheel, but at the same time produces an excess of steam in the successive stages of the turbine and correspondingly reduces the efficiency of its operation.

It is a principal object of this invention to provide a steam power system wherein the Y or necessitating any portion of the available steam or of the heat returns from the evaporators to be disadvantageously used.

It is a further object to providea system of the class described which is particularly adapted to installations employing a bleeder turbine designed to deliver predetermined quantities of steam from certain of its stages, and which system is of such nature that the return to the system of the available heat in the evaporator output and drains will not alter the respective quantities of steam withdrawn from the turbine or effect any heat loss due to the manner in which this bleeder steam is utilized.

It is a still further obj eot to provide a steam system of this type which will efliciently receive and utilize 'in the manner above described returns from the system and the steam available for preheating the boiler feed for variously modified installations, such as for instance where special apparatus, for example an economizer, is employed.

In a'sense the present apphcation con- I stitutes an improvement and a development such as is the case in a bleeder turbine installation, the steam is brought into heat transferring relation-with the feed water and its available heat utilized at pressures corresponding to the pressures of the various steam sources. In the introduction of one or more evaporator units to the system I employ as heating medium for the evaporator a certain quantity of the steam which would otherwise be utilized directly in preheating the boiler feed. The steam thus used as heating medium for the evaporator coils is preferably drawn from the source at the .highest available pressure; that is, in the case of steam drawn from a bleeder turbine the evaporators will preferably be supplied from the steamderived frdm the highest pressure bleeder stage of the turbine. That portion of the .high pressure steamnot used in the evaporator heating elements may be conducted into heat transferring relation with the boiler feed water and caused to there give up its available heat under the proper temperature and pressure conditions. The evaporator vapor output and the hot drains from the evaporator coils are brought into heat exchang- -ing relation with the boiler feed at a point intermediate the boiler feed water heater utilizing the high pressure steam'and, the condenser utilizing the steam from the next lower bleeder stage.- Thus the respective quantities of steam Withdrawn from the various stages of the turbine will not be changed from the conditions which would exist were no evaporators employed at all. In fact, the various quantities of steam bled from the respective stages of the turbine are not afiecteil either individually or collec- I tively and no power decrement can be ascribed to the system.

I have illustrated a preferred embodiment larly to Fig. 1, the system shown is designed to heat the feed water in successive steps on its way to the boilers. The main boiler feed tank 1 receives the turbine condensate and employs as its heating medium exhauststeam from the various auxiliary apparatus of the plant, and the drains from the other feed water heaters. The water is pumped from the main heater 1 through a. series of heaters orcondensers 2, 3 and 4 arranged to transfer heat to the boiler feed at successively higher pressures and temperatures.

With this type of system it is, of course, necessary that steam suitable for heating the feed water at successively highertemperatures be available. The. installation here shown'draws its steam for heating the boiler feed water from a turbine T of the bleeder type, lines 2", 3, and 4 indicating the respectlve piping for tapping ofi and conveying to the system the quantities of bleeder steam to be derived from different stages of the turbine. The condensate from the heaters 2, 3 and 4 flows through the heater drains late the boiler feed tank 1. Y

Many of the modern steam power stations are designed to utilize bleeder turbines of this type equipped todeliver at two or more stages partially used steam for the purpose of heatlng the boiler feed water in successive steps. The bleeder turbine is so designed that it operates most efliciently when there is withdrawn from itat the different bleeder stages that quantity of steam which the turbine was designed to furnish. In case a greater or lesser amount of steam is. withdrawn at any one of the bleeder stages a cer- .tain loss necessarily results due to the fact that this departure from the best operating conditions means that a certain amount of steam will not be utilized to thebest advantage. In the drawings I have shown a syshere shown is a two effect system indicated at 5. Any desired number of effects may be ill) employed, however, since for the purposes of this invention the battery of evaporators ma be considered as a single heating unit uti izing a certain amount of steam and desheet. The vapor output from the second eflect is passed to a separate condenser 6 utilizing the boiler feed water as its cooling medium. The drains from the heating coils of the two effects are joined as indicated at 7 with the condensate issuing from the heater 6, and a pump 8 is here shown for the purpose of returning the drains from the evaporator s stem to the boiler feed line.

if t e evaporator unit were so arranged with respect to the remainder of the system that the amount of bleeder steam which was designed to be withdrawn from each of the respective bleeder stages would be altered it is apparent that the introduction of the evaporator system would result in a certain power decrement due to the fact that a portion of the delivered steam would not be utilized to the best advantage. To eliminate thepossibility of'such a power decrement I place the condenser 6 for absorbing the heat from the evaporator output intermediate the boiler feed heaters 3 and 4; that is, the heat returns from the evaporator unit are trans- ;terred to the boiler feed water at a point intermediate the heater 4, which is supplied with steam derived from the same source as is the steam passed to the evaporators, and

the next preceding heater 3. With'this arrangement the introduction of the evaporator system does not affect, either individually or collectively, the respective amounts of steam which may be withdrawn and utilized at each of the bleeder stages. The operation of the blee'der stages 2" and 3 takes place exactly as though the evaporator system were till not present and the quantity of bleeder steam which would otherwise be withdrawn through the stage 4" and used directly for heating the boiler feed,'is employed in evaporating raw water but nevertheless gives up all its available heat to the boiler feed water at some temperature higher than that maintaining in the heater 3. The introduction of the evaporator system will thus not alter the efi'ect on the heating of the feed water, or, conversely, if the feed water is to be heated to a desired temperature an amount of steam will be withdrawn from the last bleeder stage 4" which is identical with that which would be required to produce the desired temperature of boiler feed water if the available heat in the steam from the bleeder stage 4 were transferred entirely in the heater 4.

This is, oficourse, neglecting the small radiation losses which are incident to the evaporator system.

To illustrate in what manner the evaporator system could be incorporated into the system so that a power decrement would result I may consider the situation which would result if, in the system shown in Fig. 1, the evaporator vapor output-were condensed in heater 2 or heater 3 instead of in a separate heater 6. If, for instance, the evaporator output were condensed in the second sta heater 3 the amount of steam which could tapped from thebleeder stage 3 would be reduced by an amount corresponding to the available heat in the evaporator output. The amount of steam thus prevented from being withdrawn at the bleeder stage 3* will, of course, traverse the successive lower stages of the turbine contributing a certain increment to the power of the turbine but losing most of its usefulness due to the fact that the lower stages of the turbine are not designed to receive this additional amount of steam,

and the excess will consequently be passed the total available energy present in the steam supplied to the system. Furthermore, if in order to compensate for this loss which would result were the evaporator output condensed in the lower stage heaters 2 and 3, a corresponding amount of steam were withdrawn from the high pressure stage 4:, the increment which this excess of steam would impart to the power of the turbine between the pressure and temperature limits represented by the stages 4 and 3 would be lost. It is true that in order to produce a desired temperature of feed water a somewhat lesser quantity of steam would have to be withdrawn from the stage 4 than would have to be withdrawn from the stage 3, but at any rate the work which this excess quantity would be capable of doing in passing from the stage 4 of the turbine and the stage 3 would be lost to the system. Similarly, if the condenser 6 employed for transferring to the boiler feed water the heat available in the evaporator output were positioned at another point in the system, for instance intermediate the heaters 2 and 3, the temperature of the boiler feed water would be prematurely raised before being admitted to the second stage heater 3, with the result that a quantity of steam less than normal from the bleeder stage 3 would be utilized. A power decrement would result in the manner above described. 4

In a system embodying my invention the steam serving as heating medium for the evaporators may be withdrawn from an desired bleeder stage but it will ordinari y be preferable to utilize for this purpose steam from the highest pressure stage as shown.

tors may receive theirsupply of steam in preference to the supply conducted to the high heat level condenser 4 so that in case at any time there is a deficienc in the quantity of steam available at t is stage the evaporators will nevertheless be permitted to retain their full quota. To accomplish this" purpose a valve 9 may be provided to regulate the amount of bleeder steam passing to the heater 4. The same result may also be obtained by arranging the system so that the entire vapor output from the bleeder stage which supplies the evaporators will be first passed through the evaporators and only the excess steam not required in the evaporators sent on to the heater 4.

r In Figure 2 I have shown a somewhat modified system particularly adapted toa plant wherein it is desired to employ an economizer for utilizing-in the heating of the boiler feed water a portion of the heat in the flue stages 2* and 3 of theturbine.

gases after issuing from the boiler. In this system the preliminary heating of .the boiler feed is accomplished in a main boiler feed tank 1, after which the feed water is successively heated in heaters 2 and 3 deriving their heating steam from the respective bleeder The number of bleeder stages employed will depend on the circumstances of a given plant and does not affect the advantages arising from the incorporation of my invention into the. system. The economizer 10 may be intro duced into any system at the desired point and is here shown intermediate the heaters 2 and 3. The eva orator unit is here illustrated as a single e ect evaporator 5deriving its heating steam fromv the high pressure bleeder stage 3 of the turbine and passing its vapor output to the condenser 6 wherein the contained heat of the vapor is transferred?- to the boiler feed water. The operation of the system is entirel similar to that of the system of Figure 1 a ove described, the chief distinction being that in Figure 2 the system is so modified that an economizer can be used.

. In this figure the condensate discharged from the

heaters

3 and 6 and from the evaporator my heating elements are returned to the boiler feed line at the proper points. For instance, the drains from the hi h pressure heater 3 are returned to the boi er feed line as indi cated at 11, after the feed has traversed the heater 3 inasmuch as the temperature of the,

condensate is as high or higher than that of the boiler feed as it issues from the heater. If desired the heater-drains may be returned to the main boiler feed tank inthe fashion employed in Figure 1, dueto the fact that the J available heat in these drains is so small that It will be understood that various modifications may be introduced into the embodiments of the invention shown. For instance, in the plant layoutindicated in Figural, the raw water supplied tothe evaporators is preheated in three

successive heaters

12, 13

and 14, the heating steam employed in' the

heaters

12 and 13 being derived directly from the bleeder stages 2 and 3 while that utilized in the third heater 14 is drawn from the vapor output of the second efiect eva orator.

t may be that the saving effected y thus preheating the evaporator feed in three stages, utilizing steam from the three respective bleeder stages of the turbine, will not,

warrant the necessary expenditure in providing three separate heaters for the evaporator feed,,in which case it will, of course, be

advisable to substitute for the three heaters shown a single heater deriving its source of heating steam from the last efiect evaporator or other convenient source. Conceivably the raw water might in suitable cases be supplied to the evaporator without preheating.

Furthermore, the evaporator system drains returned to the boiler feed supply through the medium of the pump 8 may e sent to any *otherfoint in the system, such as to the next system. Various other modi cations may be introduced within the scope of the appended claims. 1

Claims: 1. A steam power system of the class described comprisinga boiler for generating steam, steam utilizing apparatus. arrange to discharge used steam at a plurality of pressures, a plurality of boiler feed water heaters connected to receive steam therefrom at progressively increasing pressures, a boiler feed water line connecting said heaters in series, the boiler feed water being heated progressively on its way to the boiler, an evaporater connected to receive steam from said steam-utilizing apparatus, and means independent of said feed water heaters for trans ferring to the boiler feed water heat from the evaporator.

2. A steam ower system of the class described comprlsing a boiler for generating steam, a prime mover utilizing steam and havthe available ing a plurality of discharge outlets for dis charging used steam at progressively iricmasfee nected in series, the boiler feed water being ing pressures, boiler feed water heaters con nected to a plurality of said discharge outlets 'to receive heating'steam therefrom, a boiler feed water line connecting said heaters in series, the boiler feed water being heated progressively on its way to the boiler, an evaporator connected to receive heating steam from one of said discharge outlets, and means independent of said feed water heaters for transferring to the boiler feed water the heat from the vapor produced by the evaporator.

3. A steam power system of the class described comprising a boiler for generating steam, steam utilizing apparatus arranged to discharge used steam at a plurality of pressures, a plurality of boiler feed water heatcrs connected to receive steam therefrom at r essively increasing pressures, a boiler (i water line including said heaters conheated progressively on its way to the boiler,

an evaporator. connected to receive steam from said steam utilizing apparatus, an evaporator condenser connected in said boiler teed water line, means for conveying the vapor from said evaporator to said condenser,

and means for conveying the drains from said evaporator and the condensate from said condenser into said boiler feed water line.

4. A steam power system of the class described comprising a boiler for generating steam, a prime mover utilizing steam and having a plurality of discharge outlets for discharging used steam at-progressively increasing pressures, boiler feed water heaters con- J nected to a plurality of said discharge out lets toreceive heatin steam therefrom, a boiler feed water line 1ncludin connected in series, the boilerv eed waterboing heated progressively on its waytortlie boller, an eva rator connected to 7 receiveom one of said disch'arge'out-.

lets an evaporator condenser'corfiiected in d boiler feed water line, means for conve heating steam sal ing the vapor from said evaporator to said condenser, and means for conveying the drains from said evaporator and the condensate from said condenser into said boiler feed water line.

p 5. A steam power system of the class described comprisin a boiler for generating steam, steam utilizing apparatus arranged to discharge used steam at a plurality of pressures, a plurality-of boiler feed water heatcrs connected toreceive steam therefrom at' ivel increasing pressures, a boiler v water us including said heaters connected in series, the boiler feed water being heated progressively on, its way to the boiler, an evaporator, means for supplying heating rm f steam to said evaporator, an evaporator condenser connected in said boiler feed water 5 line, means for conveying the vapor from said evaporator to said evaporator condenser, and means for conveying the drains from said said heaters outlets to receive hpating steam therefrom, a boiler feed water lme connecting said heaters in series, the boiler feed water bein heated in a series of steps on its way to the oiler,

M an evaporator connected to receive heating steanrfrom one of said discharge outlets, an evaporator condenser connected in the boiler feed water line to transfer the available heat in the vapor output of the evaporator to the boiler feed water, and means'for conveying to the boiler feed line at a point beyond said condenser the drains from the heating element of the evaporator and the condensate from said condenser. 7. In a steam power plant, a boiler, a turbine receiving steam from said boiler, a plurality of extraction steam water-heating systems receiving heating steam extractedfrom said turbine at progressively increasing temperatures and pressures, each of said extrac tion systems including a heater for boiler feed water, said heaters being connected in series and said water bein heated progressively on its way to the boi er, an evaporator associated with said water-heating systems, means for supplying raw make-up water to said evaporator, means for supplying heating steam to said evaporator from one of said extraction systems, and means for transferrin the heat from the vapor produced b sai evaporator to the feed water indepen ently of each of said other extraction systems.

1 8. A steam scribed comprisin aboiler for generating steam, steam utilizing a paratus arranged to discharge steam at a p urality of pressures, heaters for the boiler feed water employing respectively as a heating medium the steam 1 discharged at said plurality of presures whereby the boiler feed water is heated in a series of steps on its way to the boiler, an evaporator deriving its'heating steam from the steam occurring at one of said pressures,

power system of the class depreheating means for the raw water supplied to said evaporator deriving their res a le at said respective pressures, and means independent of said feed water heaters for transferring to the boiler feed water-the available heat fromsaid evaporator.

9. A steam power system of the class de' ective steam suppliesfrom the steam avail- I scribed comprising a boiler for generating steam, steam utilizing apparatus arran ed to discharge used steam at a plurality o pressures, heaters forthe boiler feed water-employing respectively as heating medium the "steam discharged .at said plurality of pres- Q and means for utilizing a portion of the va-" por output of the evaporator for preheating the raw water supplied to said evaporator.

10. In a steam power plant, a boiler, a turbine receiving steam from said boiler, a plurality of extraction steam water heating systems respectively receiving heating steam extracted from said turbine at progressively increasing pressures, each of said extraction systems including a heater for the boiler feed water, a boiler feed water line including said heaters connected in series, said water being heated progressively on its way to the boiler, an evaporator associated with said water'- heating systems, means for supplying heating steam to said evaporator from one ofsaid extraction systems, and evaporator condenser connected in said boiler feed water line on the high temperature side of the feed water heater of the next lower pressure extraction system, means for conveying the vapor from said evaporator to said evaporator condenser, and means for conveying the drains from said evaporator and the condensate from said condenser into said boiler feed water line.

:unit being conducted into one of said boiler feed water heaters, preheaters for the raw water supplied to' said evaporator unit deriving their respective steam supply from the stea availableat said respective pressures, means for transferring to the boiler feed water the available heat in the vapor output from the evaporator .unit at a point intermediate the heater accommodating said excess of steam and the next preceding heater, and means for conveying to the boiler feed line at a oint beyond'the heater wherein the .availa 1e heat in the vaporioutput the heater accommodatin of the evaporator is transferred tothe boiler feed water, the drains from the heating elements of the evaporator unit and the. condensate-from said last named heater.

12. A steam power 5 stem of the class described compri "ng a iler for generating steam, steam u ihzing apparatus arrange to discharge used steam at variouspressures, heaters for the boiler feedline employingrespectively .as heating medium the steamdischarged at said various pressures whereby the boiler feed water is heated in a series of steps on its way to the boiler, an evaporator unit. deriving its heatin steam from the steam occurring at one 0 said several pressures, the excess of steam at the said pressure not accommodated in the evaporator unit being conducted into one of said boiler feed'water. heaters, means for transferring to the boiler feed water the available heat in the vapor output from the evaporator unit at a point intermediate the heater accom modating said excess of steam and the next preceding heater, and means ;for utilizing a portion of the vapor output from the evaporator unit'for preheating the raw water suppliedto said evaporator.

13. A steam power s stem of the class de- 3 scribed comprisin a iler for generating steam, steam utilizing apparatus arranged to discharge steam at various pressures, heaters for the boiler feed water employing respectively as heating medium the steam discharged at said various pressures whereby the boiler feed water. is heated in a series of steps on its way to the boiler, an evaporator derLving its heating steam from the steam occurring at one of said several pressures, the excess of steam atthe'said pressure not accommodated in the evaporator being conducted into one of said boiler feed water heaters, means'for transferring to the boiler feed water the available heating the vapor out ut from the evaporator at a point intermediate said excess of steam and thenext prece ing heater, and means for conveying to the boiler feed line the drains from theheating elements of the evaporator and the condensate from said last named means. i I

14. A steam power stem of the class described comprising a iler for generating steam, steam utihzing apparatus arranged to discharge used steam at aplurality ofressures,'a boiler feed water heating system mcluding a plurality of feed water heaters connected, to receive heating steam from said apparatus at progressively increasing pressures and to heat. the feed water progressively onits way to the boiler, an evaporator connected to receive heating steam from said steam utilizing apparatus, and means independent of said feed water heaters for transferring the available heat from the evaporator to the feed water after said water has been heated in that feed water heater scribed comprising a boiler for generating scribed comprising pressure than the evaporator, means for conwhich receives heating steam from said steam utilizing apparatus at the next lower pressure than that supplied to the evaporator.

15. A steam power system of the class desteam, a prime mover utilizing steam and having a plurality of discharge outlets for discharging used steam at progressively increasing pressures, a boiler feed water heating system including a plurality of feed water heaters connected to a plurality of said discharge outlets to receive heating steam therefrom, the feed water passing through said heaters in series and being heated progressively on its way to the boiler, an evaporator connected to receive heating steam from one of said discharge outlets, and means independent of saidfeed water heaters for transferring the heat from the vapor produced by the evaporator to the feed water after said water has been heated in that feed water heater which receives heating steam from said steam utilizing apparatus at the next lower pressure than that supplied to the evaporator.

16. A steam power system of the class dea boiler for generating steam, steam utilizing apparatus arranged to discharge used steam at a plurality of ressures, a boiler feed water heating system including a plurality of feed water heaters connected to receive heating steam from said apparatus at progressively increasing pressures, and to heat the feed water progressively on its way to the boiler, an evaporator connected to receive heating steam from said steam utilizing apparatus, an evaporator pondenser connected in said feed water heating system succeeding the feed water heater which receives its heating steam atthe next lower pressure than the evaporator, means for conveying the vapor from said evaporator to said condenser, and means for conveying the drains from said evaporator and the condensate from said condenser into said feed water heating system. 17. A steam power s stem of the class described comprising a iler for generating steam, a prlme mover utilizing steam and having a plurality of discharge outlets for discharging used steam at progressively increasing pressures, a boiler feed water heating system including feed water heaters connected to a plurality of said discharge outlets 0 receive heatin steam therefrom, the feed water passing through said heaters in series and being heated progressively on its way to the boiler, an evaporator connected to receive heating steam from one of said discharge outlets, an evaporator condenser connected in said feed water heating system succeeding the feed water heater which receives its heating steam at the next lower veying the vapor from said evaporator to said condenser, and means for conveying the drains from said evaporator and the condensate from said condenser into said feed water heating system.

18. A steam'power system of the class de scribed comprising a boiler for generating steam, a prime mover utilizing steam and having a plurality of discharge outlets for discharging used steam at progressively increasing pressures, a boiler feed water heating system including feed water heaters connected to a plurality of said discharge outlets to receive heating steam therefrom the feed water passing through said heaters in series on its way to the boiler, an evaporator connected to receive heating steam from one of said discharge outlets, an evaporator con-denser connected in said feed water heating system succeeding the feed water heater which receives its heating steam at the next lower pressure than the evaporator orator, means for supplying heating steam to said evaporator, and a heating system for heating the raw water supplied to sand evaporator including a plurality of feedwater heaters connected to a plurality of said dlscharge outlets to receive heating steam therefrom at progressively increasing pressures, the feed water passing-through said heaters in series and being heated-progressively on its way to the evaporator;

20. A steam power system of the class described comprising a boiler for generating steam, a prime mover utilizing steam and having a plurality of outlets for discharging used steam at pro essively increasing pressures, a boiler fee water heating system 1ncluding feed water heaters connected to a plurality of said discharge outlets to recelve heating steam therefrom, thefeed water passing through said heaters in series and being heated progressively on its way to the holler, an evaporator, means for supplying heat ng steam to said evaporator, and preheating means for the raw water supplled to said evaporator including a plurality of water heaters connected to receive heating steam respectively from a plurality of said outlets.

In testimony whereofI aflix my si nature.

STANLEY BR WN.

' @mmem or connection.

Patent No; '1",s46,o 47. v Y (irant'edFebrnary '23, 1932, to

STANLEY BROWN.

It is hereby certified that error appears in the printed apecification of the I above numbered patent requiring correction as follows: Page 2, line 153, for the Y I word "condenser" read heater; page 4, line 35, for the word "any" read the, and v in-the same line, for "the" read any; page. 6, line 108, claim 13, for "heating" read heat in; and that the said Letters Patent should be read with these correctionstherein that the same may conform to the record of the case in the Patent Office.

1 Signed and sealed this 31st day of May, 'A. D; 1932'.

M. J. Moore,

(Seal) .1 Actingflomisaioneroi Patenta.-