US1857650A - Method and apparatus for deaerating - Google Patents

Description

May 10, 1932.

Filed Jan. 28, 1931 2 Sheets-Sheet l I J. R. McDERME-r 1,857,650

1 METHOD AND APPARATUS FOR DEAERATNG Filed Jan. 28, 1931 2 sheets-sheet 2 May .10, 1932.

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Patented May 10, 1932 PATENT JOHN R. MCDERMET, F JEANNETTE, PENNSYLVANIA, ASSIGNOR TO ELLIOTT COM- PANY, 0F JEANNETTE, PENNSYLVANIA, A CORPORATIGN OF PENNSYLVANIA.

METHODAND APPARATUS FOR DEAERATING Application filed January 28, 1931. Serial No. 511,874.

The present invention relates broadly to the art of heat exchanging, and more particularly to this art as applicable to the deaeration of Water.

In the deaeration process, there are certain conditions the obtaining and maintaining of which are essential to the production of commercial results. ln accordance with certain known processes, it is customary to provide distinct stages or treatment Zones through which the water passes progressively.

In apparatus of such character, the water is brought into contact with heating steam in one of the zones, which for purposes of v convenience may be termed the heating stage, and is raised to atemperatureas high as it is possible to raise it in the presence of the air present in the steam originally supplied and released from the water during the heating-v thereof. It is well recognized that this tem-- perature differential between the full steam temperature and the water is such that there is a considerable air content left in the water.` This air content can be removed only by subjecting the water to treatment in the-second stage in which there is maintained a more nearly pure steam atmosphere. In such an atmosphere the remaining air in the water passes therefrom into the atmosphere to such an extent that the air inthe water and the air in the atmosphere come into pressure equilibrium. Such second stage may therefore be termed a pressure stage of Water treatment.

While the distinct two stage or zone treatment possesses certain desirable advantages from the standpoint of operation, it is open to possible criticism from the standpoint of initial cost.

I have found that it is possible to obtainV the deaeration results required commercially by subjecting the water progressively'to the action of steam in successive strata, whereby the temperature 'of the water is progressively raised, provided such strata aresubiected to a steam` Withdrawal action of such character that the stratum having the least temperature rise is subjected to the most elective with drawal. Y

By way of general introduction, it may be assumed that in an apparatus of the tray type the water is to pass successively over each of the desired number of trays, six of such trays being assumed by way: of example. Theselr trays will i obviously define horizontallysuperimposed zones or strata through which the Water progressively passes in vgoing from one tray to the other. If each of the strata is supplied with heating steam, the temperature rise in the'irst stratum will be greatest, since in this zone the coldest water comes into Contact WithA the steam. Thereafter, the temperature will be a mo'regradual one which maybe considered as generally comparable to the time element together withthe rate of air removal. Thus in .the last zone or stratum ,of treatment the temperature rise will be ofA a-minimum amount, and except'for affording a possibility of pressure. equilibrium ofthe essential that the steam atmosphere .beconf tinuously renewed. Since `the temperature rise, as 'before stated, Vis almost negligible in the last zone of treatment, the tendency toward an induced flow of steam into such Zone is likewise `.almost negligible. Under' normal conditions of operation such* zone would tend to become stagnatedand there-fore useless. It is one of the objects of the present inventionV to provi-de a method and apparatus characterized by the possibility of etecting continuous renewalof. the steam atmosphere in such zone by insuring the continuous passage of steam into such zone and its continuous removal therefrom.

Since, as before pointed out, the tempera, ture rise in the successive strata is a decreasing one, thel steam flow inducedinto such strata is likewise a decreasing one. It is further one of the objects of the invention to provide a methodv and apparatus characterized by the possibility of modifying the normal steam lowinto such strata and establishing and maintaining a condition such that the tendency toward steam flow intosuch strata is progressively increased in .contravention of the natural logari thmicglaw Y of'trays substantially horizontal of suchitrays 6 thereby providingsuperim-y InV accordance with the present invention such a result maybe accomplished by making provision for more eiective venting of the jstrata progressively in the direction of the water flow whereby the last stratum is characterized by a greater potential venting capacity than the stratum precedin@ it, the capacity preferably decreasing gradually in adirection counter to the water flow.

Since venting of the character herein contemplated represents appreciable steam removal and therefore zthe continuous withdrawal of large heat quantities from the apparatus, I preferably utilize a'withdrawing or steam flow inducing means of such nature that it is possible to continuously recover the heat of withdrawn vapors and gases and .impart the same to the water to be deaerated. A vent condenser is characterized by the ability to withdraw vapors and gases and induce the desired flow conditions, and is further characterized by the ability of transferring a large portion of the heat of the withdrawn mixture to the condensing medium. In commercial practice therefore, it is desirablein most cases to utilize a vent condenser for this purpose, although the utility' of the invention is not thus limited.

In the accompanying drawings there are shown by Vway of illustration only, more or less diagrammatically, certain preferredr embodiments ofthe present invention. In the drawings: Y

AFigure I is a diagrammatic view illustrating by a curve the relationship between the direction ofwater flow and the venting capacity; y Y

Figure'2 is a view similar to Figure l, representing diagrammatically Vthe relationship between air Vquantity and ytemperature rise with .respect to direction of water flow;

Figure is a diagrammatic view illustrating one form of apparatus producing the results graphically illustrated in Figures l and 2; an

Y Figure 4 is a view similar to Figure 3 illustrating another embodiment of the invention. In carrying out thepresent invention, there may be provided apparatusv of a number of different types so constructed as to give the conditions of operation desired. In Figure 3, I have illustrated one form of apparatus as comprisinga shell or'container 2 having an inlet 3 for the water tovbe deaerated and an outlet .4 Yeective forconveying deaerated water to the desired point Vof use. i'

t Located within thecontainer 2'is a series ly disposed and extending transversely of the container in cooperative relation to a steam inlet 5. In the illustrated embodiment I have shown sin posed strata for water treatment, which strata Yare. hereinV designated by the reference charac-ters 7 to 12 both inclusive. The water to a valve I7 in the inlet 3, whereby the rate of admission of `water to the apparatus is controlled by the rate of withdrawal of de aerated water from the outlet 4.

In the operation of the apparatus thus far described, steam from the inlet 5 will have a tendency to How into the various strata in .the direction indicated bythe arrows 18. In

the absence of special provision ofthe character contemplated by the present invention, the steam flow into the upper stratum would be relatively greater than the steam flow into the lower stratum, and the lower stratunnfci reasons pointed out, would tend to become partially or completely stagnated. In accord'- ance with the present invention I provide the respective strata with baifling or flow control ling means 19 so disposed as to give venting areasA 2OftoY 25 bothV inclusive lof progressively increasing cross sectional area from the uppermost tothe lowermost stratum. Thiis, the stratum l2 is characterized by a venting area 275 which isV materially greater than ventingarea 20'for the stratum 7.

Cooperating with ythe apparatus is a vent condenser 26 the vapor space of which is open to the interior of the container through a connection 27. While this vent 'condenser may Vbe of any one of a number of different-types, I have herein illustrated it as comprising av single pass condenser receiving water in tlie header 28 through a ysuitable connect-10h29.V

The water travels from the header 28 to a discharge header 30 through tubes 3l, and'dui'- ing such travel absorbs a large part of the heat of the vapors and gases passing through the connection 27. The condenser may be provided with a vent 32 discharging directlg.7 into the atmosphere or into an ejector, depending upon'the temperature conditions which it is desired to maintain in the apparatus itself. Y Y f A In abstractiiig heat from the vapor mixture, the vapors are condensed in the ccndeiiser, thereby decreasing their volume and tending to create-a vacuum, which tendon is eective through the connection 27 for withdrawing furtiier vapors into the condensstratum 12 than it has on the stratum 7, the" effectiveness ofthe pull increasing progressively in the direction of water iiow.

the

The condenser thus constitutes' a withdrawal means cooperating with the container Y In Figure ltliis condition is diagrammaticallly illustrated. In: the* curve oi? this figure the ordinates Vrepresent ease of venting or venting capacity having referenceto the quantity: or area, while Vthe abscissa represent the direction of water flow, having reference to the dilerent stratum of treatment. For purposes of ready comparisonl the ordinates are designated by the reference characters 20 to` 25 corresponding to the vent areas 20 to 25, while thel abscissa are designated bythe references 7 lso-1:2', having reference to the stratum themselves. `The representative curve @indicates diagrammatically the variation` in the elifectiveness of venting in the direction of water flow and illustratesv clearly a maximum edectiveness.progressively on the strata the direction of water flow.

In Figure 2 there is illustrated diagrammatically the relationship between air quantities, temperature rise and natural tendency toward. steamiow as compared to the direction` of water llow. In this figure the ordinates'reprcsent air quantity removed as a percentage ot the total air available, or temperL resent direction of water flow and are desig-` nated similarly to Figure 1. The ordinates on the contrary are designated 7 a to 12a, both inclusive. The resulting curve C indicates temperature rise of the water. By reference to this curve it will be seen that the water travelling through the stratum 7 would naturally induce a maximum percentage quantity represented by the amount 7a of the initial low of the heating steam, while the water flowing through the successive zones or strata 8 to 12 would normally induce progressively smaller percentages of initial steam iow, designated as 8a to 12a inclusive.

The values 7 a to 12a also represent the air quantities released, the air quantities gradually decreasing under normal conditions as the water is successively treated until the removal curve becomes substantially parallel to steam quantity. Thelcurve is thus ordinarily referred to as asymptotic and illustrates the diliculty under natural conditions of operation of edecting complete air removal. In accordance with applicants invention the air quantity 12a is removed with a quantity of steam represented by the ordinate 25 of Figure 1, which is a maximum steam flow from the stratum, whilev the air quantity 7 a is removed by a minimum steam quantity from the stratum designated by the ordinate 20 of Figure 1. The maximum steam llow from the stratum for the minimum air content insures the continuous maintenance of a substantially pure steam atmosphere in which pressure equilibrium may be advantageously accomplished.

In Figure 4f, I' have illustrated a slightly modified embodiment of the/invention which parts corresponding to the partshereto-fore described are designated' by the same reference, having in each instance a value of added thereto. In this embodiment the successive strata 107 to 112, bothv inclusive,

arev formed by trays 106. The outlet from the stratum 107 is blocked `by a baille 119 ot maximum size, thus adording a vent area of' minimum size.vr The size of the baliles119 is progressively decreasedin .the directionoli water flow, thereby providing withdrawal areas 120 to 125 both inclusivevof progressively increasing size, whereby the maximum venting capacity is-obtained in connection withY the last stratum 112. f `In this apparatus the conditions of operation willbecontrary to conditions of normalv operation in. an open heater ,of the tray type, for example, and such as to induce a withdrawal eliect which is greatest in the zone of least temperature rise and smallest in the lzone of maximum temi-Ik perature rise. The result is to always main tain steam atmospheres such as tol facilitate pressure equilibrium and `air removal by be otherwise formed and that the isolation or separation of the respective Zones or strata may be modified or changed 'in accordance with the particular design of the'apparatus. QI' claim n y 1. InV the method ofvdeaerating, the steps comprising passing the water tofbe deaerated through a heat exchanger, progressively subPV jecting the water to theaction of steam in successive strata, continuously separately withdrawing steam vand released air fromv such strata, and' subjecting the strata .having theleast vtemperature rise to an increased withdrawal effectiveness.- v

f 2. In the method'of deaeratingtlie steps comprising passing theiwater to be dea-erated comprisingpassing the water to be deaerated,

through a heat exchanger, progressively sub.- jectingthe water tothe action of steam in successive strata, Vcontinuously separately withdrawing'steam and released air from such strata,` and progressively increasing, the

` through va heating' apparatus, progressively subjecting the water to the'action of steam inv successive strata, continuously separately withdrawing .steam and released air from all of the vstrata to a common point, and subjecting the stratum having the least temperature rise tothe most effective withdrawal. Y

6. In the method of deaerating, the steps comprising passing the water to be deaerated Y through a heating apparatus, progressively 125 subjecting the water to the action of steam in successive stratain said heat exchanger, continuously separately 'withdrawing steam and released air from each stratum, combining the steam and air at a common point, and subjecting the stratum having the least'temperature rise to the most effective withdrawal. p 7. In the method of deaerating,the .steps comprising passing the Water to be`deaerated through a heat exchanger, progressively-'subjecting the Water to the action of steam in successive strata, controlling the steamliovvV through such strata in such manner asito produce a gradually increasing pullthrough the strata in the direction'of water flow, and withdrawing the released air from the heat exchanger. 8. In the method of deaerating, the steps comprising passing the water to bedeaerated through a heat exchanger, progressively subjecting the water to the action of steam in a plurality of substantially horizontally extending superimposed strata, and controlling the steam How through such strat-a to'give a V- 1 50 progressively increasing steam pull through the strata in theldirection of the water flow.

9. In the methodY of deaerating,.the steps comprising passing the water to be deaerated through a heat exchanger, progressively subjecting the waterto the action ofksteam -in successive strata, andr'progressively increasing the venting of the strata in the direction of water flow therethrough.; Y i 10. In a deaerator, a container, a plurality y 50ct trays therein formingV superimposed water treating strata, and individual Vents for said strata of progressively increasingl size inthe direction of water flow therethrough. l' l1. In a deaerator, a container, a plural- 65 ity of trays Vtherein forming superimposed water treating strata, individual vents for said strata of progressively increasing size in the direction of water flow therethrough, and common means operative on all ofsaid vents for inducing a steamzflow through the various strata.

12. In a deaerator, a container, a plurality of trays therein forming superimposed water treating strata, individual vents for said strata of progressively increasing size in the direction of water flow therethrough, and How inducing means cooperating with said vents.

l13. In a deaerator, a container having a mixture outlet and la water inlet, a vent condenser having its vapor Space operatively connected to saidoutlet and having its tube space connected to said inlet, means for controlling v my hand. v JOI-IKN R. MCDERMET.

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