US1591822A - Heater - Google Patents

Description

July 6 1926. 1,591,822

` L. HELANDER HEATER Filed Sept. 12, 1923 2 Sheets-Sheet l W 57 52 \Q-/58 59 .LL @215 60 364 y lf EL@ 4in" "mw" TOR ATTORNEY .uly- 6 3.926s 1,591,822

L.. HELANDER HEATER Filed Sept. 12, 1923 2 Sheets-Sheet 2 Linn/felamir INVENTOR ATTORNEY ltih?.

.eti fFICE.

LINN HELAEDER, OF EAST PITTSBURGH, PENNSYLVANIA., ASSIGNOR TO WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CURPORATION OF PENNSYL- VANIA.

` HEATER.

Application filed September 12, 1823. Serial N'o. 662,349.

This invention relates to multiple stage heaters, more particularly to heaters in which steam is utilized for heating water for industrial processes, boiler feed, and the like, and it has for an object to provide a heater of the character designated which shall utilize the heat of the steam more economically than has been possible heretofore in heaters of this character. It is a further object o-f my invention to provide means in connection with an apparatus of the character designated which shall insure the primary steam consumer, as for example, a steam turbine from which the steam for process heating is taken, from injury due to flooding of the heaters and the steam Vconnections leading thereto.

These and other objects, which are made `more manifest in the further description of myinvention may be' attained by the apparatus herein described and illustrated in the accompanying drawings in which Fig. 1 lis a diagrammatic View partially in section and partially in elevation of a multiple stage heater embodying my invention; Fig. 2 is a sectional elevation of a piston motor for controlling` the supply of steam to respective pressure stages of the heater; Fig. 3 is a Vdiagrammatic view of a modification of the construction illustrated in Fig. 1 employed. in conjunction with a main` turbine and a house turbine and Fig. fl is a diagrammatic view of a still further modification of the construction illustrated inFig. 1 in which barometric connections displace the pumps necessary to circulatethe water to vbe heated through the heatin system.

- recording to the present invention, I employ a ietheater of any suitable type, in construction similar to the ordinary barometric or jet condenser, as a firsbstage heater, the water therefrom being discharged into the circulating passages of a surfaceheat er of any ordinary construction. I have found it advisable to have at least one jet or contact heater arranged in the series because of its deaerating qualities. The discharge Water from the surface heater may pass to one'or more surface heaters, or directly to a device for utilizing the heated water. rthis karrangement is particularly adapted for use of low-pressure steam and permits the water to be heated by the absorp- -tion of heat from steam at a high degree offvaeuum in'the first-stage heater and to pass into the second and any succeeding heaters at an increased temperature, and there absorb further heat of steam at increasing absolute pressures. A further economy is attained by leading thel noncondensable fluids from the last stage heater progressively through theA several heaters, thus recovering both the heat and the water carried by the uncondensable iiuids, and finally discharging the non-condensable fluids from the first-stage heater only after contact with the cold first-stage cooling` water and after the heat and water vapor has been recovered therefrom as completely as possible. The invention further contemplates the conveying of condensate from the surface heaters to the first-stage jet heater so that, where pumps are necessary for re moving the condensate and air, a single air pump and a single condensate pump, preferably mounted on the same shaft suffice for all heaters. Further means are provided for forming a liquid seal in a condensate pipe lea-ding from the surface heaters and means for controlling the relative pressure conditions in the several heaters is also provided.

In Fig. 1, I show a multiple stage heater composed of a first-stage jet heater and a second-stage surface heater 11. he jet yhea-ter 10 comprises a mixing chamber 12,

a steam inlet 13, an annular water box 14 surrounding the mixing chamber and having an inlet 15 and nozzles 16- arranged to deliver sprays of water across the mixing chamber 12. The mixing chamber 12 is provided at its lower portion with a converging conoidal apron 17 which serves to direct Huid from the mixing4 chamber 12 to a well 1S disposed at t-he lower portion of the heater. A centrifugal water pump 20 mounted on a power shaft 21 is arranged to withdraw water from the well 18 and discharge it through a pipe 22. A non-condensable fluid pipe 23 leads from the upper portion of the well 18 to a pump 24 which is preferably mounted upon the same power shaft 21 as the pump 20, the discharged noncondensable fluids being delivered therefrom tothe atmosphere.

The second-stage heater 11 may be of any well-lniown construction and as shown comprises a cylindrical shell 30, the ends of which are closed by water boxes 31 and 32. Tubes '3.3 traverse the spaceowithin the cylindrical shell SO-and are secured in the water boxes in the ordinary manner. The water oz; 3l is provided with an inlet compartment 35 with which the pipe 22 communieates and an outlet compartment 36 trom which the heated water is discharged through an outlet 3T to other heaters orto use. A steam inlet 58, adapted tor connection with a source of steam supply, is centrallvv disposed in an upper portion ot the shell 30.

The two heaters are connected one to the other through the water pipe 22, already described. and also through a vent pipe -l'tl and a condensate discharge pipe il. The veut. pipe t() leads Vtrom a central 'portion et the .steam space within the cylindrical .shell fill to an upper portion ot the arising chamber l2. and is preterablv provided with a valve l2. Inter-posed in the condersate dischareje pipe stl a water sealing or regulatinL chamber 43, situated adjacent to and at the level of the bottom ot the heater ll. The pipe ell leads from the bottom ot the steam chamber of the heater ll into the chamber 4:3, and a second section ot pipe -lfl leads from the bottom ot the chamber to the v:Vil 18 of the lirst-stage heater l0. fr vent 45 connects the upper portion ot the regulating chamber ,43 to an upper portion et the steam chamber ot the surlace heater. so that the level ot the condensate in the i latingl chamber, is at all times the sanne as that in the heater ll. A valve iti is arranged within the regulating chamber 4,3 to control dis charge ot condensate therefrom to the well 1S o'l the first-stage heater. and is actuated bv a float et? in such manner that the valve 46 cuts oit the flow ot condensate when the level of the condensate in the heater ll talls to a predetermined low level.

A barometrie overtlow pipe t8 having au admission valve l?) niav also comuninicatr.` with the regulating chamber the arrangement-being such that the valve is opened bv the float si? upon an excessive rise ot' condensate therein. The excess condensate conveyed through the pipe i8 to a wate' veal 50 disposed at such level with respect to the regulating chamber as to maintain a baro! metric head in the pipe 4S.

lt may be desirable under certain conditions to regulate the steam supply ot the second stage heater in response to pressure conditions within the tiret-stage heater. To accomplish this. l place a valve 52 in the steam inlet BS ot the second-st ge healer. which valve is arranged to he operated h v a piston motor through a rod its shown in Fig. 2, the piston motor afl has a casing divided by a piston 56 into a firststage pressure chamber 5T and a secondstage. pressure chamber Sconnected respectivelyv throughpipes 59 and VG0 to Vthe tirst and'sec'ondlstage heaters. The piston '56 is subjected on the side to which the rod 5l is secured to the pressure prevailing within the second-stage heater and to a supplemental variable pressure by a suitable spring (ll. @n the opposite side. it is subjected to the pressure prevailing within the lust-:stage heater l0. lligidl'v secured to the piston at',

hv a rod ($2 is an auxiliary piston (Sil. This auxiliar)T piston, which ma)v be ol dill'erent diameter than the piston 5G. subjected on one side to the pressure prevailing within the first-stage heater and on its opposite side to the pressure ot the atmosphere. Should it be desired to operate the heaters l() and ll at pressures above atmosphere. hydraulic pressure ma)v be emplo ved to act upon the outer 'tace et the auxiliarv pistou 63. The dii'l'erenctl in pressure between the atmosphere and that ot the lirst-stage heater determines the amount ot torce exerted bv the auxiliar)Y piston G53 through the rod 0;. upon the piston 56.

rfhe first-stage heater is preterablv provided with a vacuum breaker (if) ot an); wellknown construction so arranged as to place the heater in communication with the atmosphere upon an excessive rise ot' water in the well 1S. in order to stop the flow ot water through the nozzle 1G. and thus to prevent the tloodiug ot the steam conmctions leading to the heater. As shown, a chamber communicates with the upper portion of the well 18 through a port T1 and with the atmosphere through a port '72. A valve Tfcontrols the port. 72 and is operatively connected 1o a tloat T4. the arrangement being such thatl upon water in the well l reachinfr the level ot' port 7l the chamber 7U is imiuediatel)y tilled with water, the float Tl raised to open the valve T3. thus placing the interior ot the heater l() in communication with the atmosphere.

rl`he operation ot the apparatus is readilv understood 'trom the above desi-ripiani. Steam at a low absolute pressure. prefer-- abl)v exhaust steam from a prime mover. cnters the first-stage through the inlet lil. The water to be heated enters the water box ll through the inlet l5 and is spra'ved into the steam in the mixing eliamller 1Q thrtnigh the nozzles lll. lvfithin this chamber. tht` steam is condensed and the temperature ol" the water raised. The heated water falls into the well 1S whence it is conveyed bv the pump and the pipe to the second-stage surface heater ll. The partially heated water makes two passes through the tubes Ill of the surface heater ll and is discharged therefrom through the port 3T. The second-stage heater is supplied with steam at higher pressure and temperature than the tlrst--stage heater and consequently further heats the water passing through the tubes Il?, thereof.

Since "src/am normally contains A4a email ers are then Withdrawn from the first-stage heater through the pipe 23 and are discharged by the pump 24 into the atmosphere.

The condensate from the steam utilized in heating the Water in the surface heater' 11 is preferably conveyed to the vvell 18 of the heater 10 by means of the pipe 41, in order that a single pump 20 may serve to Withdraw theWater from both heaters. Since the pressure in the heater 11 is higher than that in the heater 10, it is necessary to intel'- pose a sealing means in the condensate pipe V41 to prevent incompletely condensed steam `from passing from the surface heater into the jet heater. The sealing means employed in the construction illustrated in Fig. 1 comprise a chamber 43 in which a certain level ot vater is at all times maintained. When the water is at a higher level a loat 47 operates to open the valve 46 and permits the tlovv of condensate from the regulating chamber 43 to the Well 1S. It for any reason an excessive amount ot' Water should collect in the chamber 43, the valve-controlled barometric overflow 48 drains away the excess and thus prevents the heater 11 from being flooded.

Flooding of the irst-stage heater is also prevented by the provision of the vacuum breaker l0 which is designed to place the heater 1() in direct communication with the atmosphere upon a predetermined rise of Water level therein. Each heater is thus provided with an independent means for preventing the flooding ot the heater and the steam connections leading thereto,V an important desideratum When the steam for heating is supplied from theexhaust or Jfrom bleeder passages oi a prime mover.

The pressure-control valve 52 serves to regulate the quantity ot steam entering the second-stage heater in response to pressure conditions within vthe lirst-st age heater. Any increase ot pressure in the tiret-stage heater will be transmitted to the first-stage chamber 57 ofthepiston motor 53. `Within this chamber, the additional pressure moves the piston 56 to compress the spring x51 an amount sutlicient to produce an equilibrium of forces. This movement of the piston 56 opens Wider the valve 52, whereupon additional ysteam is admitted through the inlet 38 to the second-stage heater 11 until such time as the pressure builds up a sutlicient amount to move the piston 56 to restrict the supply. In this manner, the relative pressures prevailing Within the second-stage heater 11 are maintained at pre-determined higher values than those prevailing Within the lirst-stage heater 10.

The relative pressure values prevailing Within the first and second-stage heaters may be represented by a straight-line graph. By' selecting tvvo relative pressure values such as 5 pounds absolute in the first-stage heater corresponds to 10 pounds absolute in the second-stage heater, and 10 pounds in the tiret-stage heater corresponds to 12 pounds absolute in the second-stage heater, a straigl'it-line may be established. From this line, the relative pressures prevailing simultaneously in the heaters throughout the entire range ot' operation may he ascertained.

Should the level of the iva-ter in the iirststage heater reach a height sufficient to open the vacuum breaker, the tiret-stage chamber 57 oft the valve motor 58 is placed in communication with the atmosphere. rlhe additional pressure present therein moves the piston to compress the spring 61 to open VWider the valve 52, whereupon additional steam is admitted to the second-stage heater 11 until such time the pressure prevailing therein is sutlicient to throw the piston 5G together With the rod 62 and the auxiliary piston 53 to the lett the required distance to completely close the valve 52 in the steam inlet ot the second-stage heater. This operation is entirely automatic and When vacuum conditions have been reestablished in the heater 10 the valve 52 is reopcned to permit steam to enter the second-stage heater as under normal operating conditions.

later heating apparatus constructed as above described operates With a Vhigh degree oli' thermal etiiciency, since all the heat of the steam is utilized as completely as possible, including the heat ot the non-condensable fluids which is largely extracted during the passage of these fluids through heaters of progressive low r temperature prior to their Withdrawal from the system. A further advantage arises in the need of but a single non-condensahle fluid pump, and a single Water pump, an arrangement which pernlits a considerable economy of motive power for the operation ot the pumps and a reduced cost in the manufacture of the multiple stage heater.

in Fig. E, l have illustrated a diagrammatic arrangement of apparatus similar to that above described in relation to Fig. 1

yand for the purpose of this specification a detailed description thereof is deemed unnecessary. The arrangement ot apparatus comprises-a main turbine 79 with its condenser Si and a house turbine S0 exhaust ing into a combined `iet condenser and lirststage heater l0. A pluralitv of tubular surface heaters ll and 1l are arranged in series with the first-stage heater l0. The water to be heated. is collected in a feed tank Sie which receives the condensate removed from the main condenser Sl b v the pump 85. In addition thereto, make-up ivater is supplied through a suitable connection ST ivhicli may, if desired7 be provided ivith automatic regulating means for maintaining a predetermined level ot Water in the tank. The Water is removed from the tank Si and conveyed through the conduit S8 by means of the vacuum prevailing in the first-stage jet heater l0, in which it mingles ivith the exhaust from the house turbine 80. 'Vithin this combined heater and condenser, the exhaust steam is condensed and the temperature of the Water is raised. ri`he heated water is then conveyed bv the pump 2O and conduit 22 to the second-stage heater ll and thence through the conduit LL to the third-stage heater ll. The second and third-stage heaters ll and ll are of the surface type, and maj/Y be of an)y n'elldtnovvn construction`r but are preferablyv similar to that described in relation to the second-stage heater shown in Fig. l. After being discnarged from the thirdstage heater ll at S9, the Water may be utilized for feeding boilers, or, a portion thereof may be used for that purpose and a portion utilized for industrial purposes.

The temperature. and pressure maintained in the second and third-stage heaters l1 and 11 are relativelyv higher than that maintained in the heater preceding so that the temperature of the Water is successivel)Y increased b v being passed in series through the three heaters. Steam of a pressure slightlyv higher than that corresponding to the vacuum prevailing` in the first-stage jet heater 107 is preferably supplied from a bleeding connection S553 provided in the main turbine T9, and conveved through the conduit S9 to the inlet nozzle 3S of the secondstage heater ll. Steam of still relativelyv higher pressure is taken from a second bleeding connection 8:2 provided in the main turbine 75). and conveyed through the conduit Ul. to the inlet nozzle 3S of the third stage heater 1l.

.ln order to provide automatic means tor maintaining the aforesaid relatively higher pressures in each succeeding heater in the series, I provide regulating devices 53 and 5S and a vacuum breaker 69. The vacuum breaker is similar to that described in relation to and shovvn inFig. l, and b v which the first-stage iet heater l0 is placed in communication vvith the atmosphere upon an excessive rise of vvater therein. The regulating devices ,53' and 5: control respectively through rods 5e and 54; the valves 52 and 52 in the steam inlet nozzles 38 and 3S of the heaters il and l1. Thevv are similar in construction to the regulating devices described in relation to and shoivn in Figs. l and 2 and serve to control the amount of steam entering the succeedingI heater in response to the pressure prevailing Within the heater preceding in the series. These pressures in the heaters are conveyed to the regulating devices through suitable conduits 59. 59, (30 and G0. The regulating device 53 also includes means for completel).v closing the valve 52 upon a functioning of the vacuum breaker (3f), and the regulating device 5&3 closes the valve 52 upon a pre- .lotermincd rise of pressure ivithin the sccoud-sta 3;, heater il.

The air and non-condensable fluids contained in the steam are econoniicallv removed from the heaters and the heat largcl;v recovered therefrom bv venting through the conduit l0 the third-stage heater ll into the second-stage heater ll in vvhich :i relativelyv lower pressure is maintained. This heater is in turn vented by means of the conduit Lt0 into the first-stage jet heater 10. rfue non-condensable fluids from both surface heaters and the jet heater are finall)v removed from the jet heater through the conduit 23 b v means of an air pump 2l and discharged to the atmosphere. In this Wav, a single air pump is sufficient for all three heaters.

rl"he condensate from the steam utilized in heating the Water in the surface heaters conveyed to the firststane jetl heater in a manner similar to the removal of the noncondensed fiuids. Condensate from the third-stage heater ll is removed therefron'i, b v the second-stage. heater ll through the conduit Jil, and the first-stage heater l0 in turn removes the condensate from the second-stage heater ll through the couduit Lil. lVithin the first-stage jet heater`r it combines With the vvater to be heated and is ren'roved therefrom b v the pump Qt) and discharged to the s vstem. As the heaters are maintained at relativeliv lower p1' ,.5 n .1 in the direction of tion' of thc condensate, sealing means. similar to that described in relation to and shown in Fig. l. are provided in the conduits l-l-l and 4:1. for preventing incompleteljy condensed steam from passingbetween the heaters. liach o: the sealing or regulating! chambers 43 and 13 is vented bv means ot the conduits il-5 and e5 to the respective surface heaters il and ll from which it receives condensate, and nre.)v he so located as to maintain a pre determined level of Water therein. In order to insure that this level of Water ma;v not reach such height as may endanger the main turbine 80, barometric overflow pipes 45 and 415', maj; beprovided similarwto loo that shown in Fig. 1. These ipes discharge into the'feed tank 81 and ave their outlet portions submerged therein.

The above outlined arrangement of apparatus provides a very efficient and highly economical method of heating water. It is especiallyadapted for installations which are required to produce a large amount of hot water for industrial processes in addition to that required for feeding the boilers. A considerable amountof water may be heated to any desired temperature by combining a sufiicient number of surface heaters of required capacity, with the jet or contact heater. irrespective of the number of heaters employed, a single air pump and a single water pump only are required, thereby entailing the expenditure of a minimum amount of energy for the operation of the auxiliary machinery.

rlhe multiple-stage heater illustrated in Fig. L1 represents a modified construction which is particularlyY adapted for use where ample head room is available. for the installation of the apparatus. ln this construction, no removal water `pump is re quired, water being withdrawn from the heater by barometric connections. The firststage heater 100 is similar to the first-stage heater 10, above described, and, as shown, comprises a mixing chamber 101, a steam inlet 102, an annular water box 103 having an inlet 104, and nozzles 105 for discharging jets of water across the mixingchamber. The mixing chamber is provided in its lower portion with a converging conoidal apron 106 which serves to deliver the heated water to a Well 107 at the lower portion of the heater.

A second-stage surface heater 110'is located at a considerably lower level than the heater 100 and receives water from the well 107 through `a semi-barometric connection 111. The'second surface stage heater 110 Imay be of'any well-known construction. As shown. itconsists ofa cylindrical shell 112, water boxes 113 and 114, and tubes 115, the latter traversing the space within the cylin` dric'alshell and secured to the water boxes in the usual manner. rlhe water box 113 is provided Vwith an inlet compartment 116 with which the pipe 111 communicates, and an outlet compartment 117 from which the heated water is discharged through an outlet 118. A steam inlet 119 is suitably disposed in the cylindrical shell 112. The water delivered from the outlet 118 of the heater 110 passes downwardly through a vsemi-barometric connection 120 to a pump sump 121, the lower end of the barometric connection 120 being immersed in the water of the sump. The condensate from the heater 110 may be withdrawn by any suitable means through a pipe 122. As shown,

the pipe 122 may lead to the sump 121,

where the barometric head is sutcient to dra-in the condensate from the heater 110. The discharge portion of thepipe is immersed in the water of the sump. A vent connection 123 leads from an upper portion of the steam chamber of the heater 110 to an upper portion of the mixing chamber 101 and is preferably provided with a valve 1211. Automatic control means similar to that shown and described in relation to Figs. 1 and 2 may be provided.

The operation of the apparatus illustrated in Fig. A is similar to that already described in relation to Fig. 1. rlhe water to be heated enters the first-stage heater through the inlet 101, water box 103 and nozzles 105, where it mingles with and condenses the steam admitted through the inlet 102 and then passes downwardly through the well 107 and baroe metric connection 111 to the surface heater 110. The water traversing the second-stage heater 110 is subjected to steam at a higher pressure and temperature than that delivered to the first-stage heater 100 and is finally discharged through the barometric connection 120 to the sump 121 from which the water is conveyed to use. The non-condensable iluids in a counter direction to the flow of water from the second-stage heater to the first-stage heater in yorder to utilize fully the heat of the steam. rille condensate from the heater 110 may be mingled with the heated water or may be withdrawn independently for use if desired. lt is to be understood that a plurality of surface heaters at succes? siv-ely lower levels may be utilized in the construction shown in Fig. 1, the heaterI preferably receiving steam at successively higher pressures and temperatures so as to effect a gradual and constant heating of the water flowing therethrough.

llVhile I have shown my invention in but three forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing fromthe spirit thereof, and I desire, thereforethat only such lin'iitations shalll be placed thereupon as are inipc-s'ed by the prior art or as are specifically set forth in the appended claims.

Vfhat l claim is:

1. A multiple-stage heater comprising a contact heater and a surface heater.y means for delivering separate supplies of steam to each beaten-means for passing water to'be heated through the heaters in series, and means for venting the. surface heater into the contact heater.

2. A multiple-stage heater compris" contact heater and a plurality of surface heaters, means forrdelivering separate sup plies of steam to each heater, the steam supplied to` each successive heater being at a relatively higher pressure, means for passing llll rse

lli

the w.ter to be heated through the heaters in series, means for venting each heater. with the exception of the heater first in the series, into the heater of successively lower pressure, and means for witlulravfing noncondensahle tiuids from the heater liist in the series.

B. A multiple-stage heater comprising a lirst-stage contact heater and a second-stage surface heater, means for delivering separate supplies of steam to each heater, the steam delivered to the surface heater being at a higher pressure, means for passing water to be heated through the heaters in series, meansl for venting` the surface heater into the con-- tact heater, and means for withdrawing noncondensahle tiuids from the contact heater.

l.. A nmltiple-stage heater comprising a first-stage Contact heater and a second-stage surface heater, means for delivering separate supplies of steam to each heater, the steam delivered to the surface heater being at a higher pressure, means for passing water to he heated through the heaters in series, and means for delivering condensate from the surface heater into the Contact heater.

5. A multiple-stage heater comprising a first-stage contact heater and a second-stage sui-tace heater, means for delivering separate supplies of steam to each heater, the steam delivered to the surface heater being at a higher pressure, means for passing water to he heated through the heaters in series, means for delivering condensate from the surface heater into the contact heater, and means for withdrawing condensate from the contact heater.

G. A multiple-stage heater comprising a contact heater and a. plurality of surface heaters, means for delivering separate supplies of steam to each heater, the steam supplied to each successive heater being ata relatively higher pressure, means for passing the water to be heated through the heaters in series, Ameans for venting each heater. with the exception of the heater first in the series, into the heater of successively lower pressure, and means for delivering conden- .ate from each heater, except the first in the series, into the heater of successively lower 7. A multiple-stage heater comprising a rst-stage contact heater and a secondstage surface heater, means for delivering separate supplies of steam to each heater, the steam delivered to the surface heater being at a higher pressure, means for passing water to beA heated through the heaters in series, means for delivering condensate from the surface heater into the contact heater, and means .establishing a seal in said condensate delivering means for preventing the passage of steam therethrough.

S. A multiple-stage heater comprising a contact heater and a plurality of surface heaters, means for delivering separate .supplies of steam to each heater, the steam supplied to each successive heater igieing at a relatively higher pressure, means for pas-'- ing water to be heated through the heaters in series, means for delivering condensate from each heater, with the exception of thrheater lirst in the series, into the heater of successively lower pressure, and means establishing a seal in each of said condensate delivering means for preventing the pasage of steam therethrough.

9. A multiple-stage heater comprising a lirst-stage contact heater and second-stage surface heater, means for delivering separat@` supplies of steam to each heater, the steam delivered to the surface heater heine' at a higher pressure, means for passing water to be heated through the heaters in series. means for delivering condensate from the surface heater into the contact heater, means establishing a seal in said condensate delivering means for preventing the passage of steam therethrough, said sealing means including a barometric overflow connection. whereby the level of condensate within the surface heater may be maintained within definite working limits.

l0. A multiple-stage heater comprising a Contact heater and a pluraiitv of surface heaters, means for delivering separate supplies of steam to each heater, the steam supplied to each successive heater being at a relatively higher pressure, means for passing water to be heated through t-he heaters in series, means for delivering condensate from each heater, with the exception of thi heater first in the series, into the heater ot' successively lower pressure. and means establishing a seal in each of said condensate delivering means for preventing the passage of steam therethrough, each of said scalini,r means including a barometric overflow. whereby the level of the condensate within the surface heaters may be maintained within delinite working limits.

ll. A multiple-stage heater comprising` a first-stage contact heater and a second-stage surface heater. means for delivering separate supplies of steam to each heater, the steam delivered to the surface heater being at a higher pressure, means for passing water to be heated through the heaters in series, means for delivering condensate from the surface heater into the contact heater. means establishing a seal in said condensate delivering means for preventing the passage of steam therethrough, said sealing means including a barometrie overfiow connection. whereby the level of condensate within the surface heater may be maintained within definite working limits, said sealing means including a closed chamber so disposed as to contain condensate at a level of the comien- Adisclmrge of condensate into sate in the surface heater, a harometric overflow communicating with said chamber, and a float controlled valve for permitting said overflow when the condensate in the surface heater rises above a predetermined level.

12. A. multiple-stage heater comprising a Y plurality of heaters, means for delivering` separate supplies of steam to each heater, interconnecting means for passing Water to h telthr 'h tl h ate" s nl oe. ea c .ougn `ie eatcis in series, an( means responsive to the pressure in each preceding heater forcontrolling the deliver?,Y of

steam to the heater next in the series.

13. A multiple-stage heater comprising plurality of heaters, means for deliv ring separate supplies of steam to each heater', interconnecting means for passing Water to be heated through the heaters in series, and a device responsive to the pressure in each preceding heater for controlling the deliverj,T of steam to the heater next in the series, said device including means for automat-ically shutting off the deliveijvY of steam upon a predetermined rise in pressure in the preceding heater in the series.

14. A multiple-stage heater comprising a first-.stage heater and a second-stage heater, means for delivering separate supplies of steam to each heater, interconnecting means for passing Water to he heated through the heaters in series, and means responsive to pressure in the first-stage heater for controlling the deliver;7 of steam te the secondstage heater.

15. A multiple-stage heater comprising a first-stage contact heater and a second-stage surface heater, means for delivering separat-e supplies of steam to each heater, means for passing Water to be heated through the heaters in series, and means responsive to the pressure in the contact heater for maintaining predetermined greater pressures in the surface heater.

16. A multiple-stage heater comprising a first-stage heater and ay second-stage heater, means for delivering separate supplies ot' steam to each heater, the steam delivered to the surface heater beine' at a higher pressure, intereo nnecting` means for passing Water to he heated through the heaters in series, means responsive to pressure in the Erst-stage heater for controlling the delivery of steam to the second-stage heater, means for vent-ing the second-stage heater into the first-stage heater, and means for Withdrawing non-condensable iiuids from the firststage heater.

17. A multiple-stage heater comprising a first-stage contact heater and second-stage surface heater, means for delivering separate supplies of steam to each heater, means for passing Water to be heated through the heaters in series, and means responsive to the pressure in the contact heater for controlling' the deliver5T of steam to the surface heater.

18. A multiple-stage heater comprising first-stage conta t heater and a second-stage heater, means for delivering' separate supplies of steam to each heater, means for passing Water to be heated through the heaters in series, a vacuum breaker for the contact heater operable upon a predetermined rise of Water level therein, and means operable when the vacuum breairer acts for shutting oil the steam supply to the second-stage heater.

19. A multiple-stage heater comprising a rst-stage contact heater and a second-stage surface heater, means for delivering separate supplies of steam to each heater, the steam delivered to the surface heater heing at a. high pressure, means for passing' Water through the heaters in series, a vacuum breaker for the contact heater operable upon a predetermined rise of Water level there-` in, and a device responsive to the pressure in the contact heater for controlling the delivery of steam to the second-stage surface heater, said device including means for automatically shutting off the steam supply to the second-stage surface heater upon a functioning of the vacuum breaker.

20. A multiple stage heater comprising a first stage heater and a. plurality of surface heaters, means for delivering separate supplies of steam to each heater, the steam supplied to each successive heater being at a relatively higher pressure, means for passing the Water to be heated through the heaters in series, and means for venting each heater, With the exception of the heater of lowest pressure, into the heater of successively lower pressure.

21. A multiple stage heater comprising a first stage heat/er and a second stage surface heater, means for delivering separate supplies of' steam to each hea-ter, means vtor passing Water to be heated through the heaters in series, means for venti ,D second stage heater to the stage heater, and means for ufithdrauf'ing non-condensable fluids from the first stage heater.

22. A multiple heater comprising a first stage heater and a second. stage heater, means for delivering' separate supplies of steam to 'each heater, the steam delivered to the second stage heater being at a higher pressure, means for passing Water to he heated through the heaters in series, and means for venting the second heater into the first stage heater.

1n testimony whereof, i have hereunto subscribed my name this 15th da)7 of August 1923.

LNN HELANDER.

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