US1637558A - Surface condenser and method - Google Patents

Description

Aug. 2 1927.

F. M. DOYLE SURFACE CONDENSER AND METHOD Filed Sept. 15, 1926 3 Sheets-Sheet l 70 0010019775 PUMP INVENTOR flail/z M fiayla M ATTORNEY Aug, 2,1927. 1,637,558

F. M. DOYLE SURFACE CONDENSER AND METHOD Filed Sept/15, 1926 3 Sheets-Sheet 2 I 5 4 4 9 {iv/lg g4 1 a Frank M. Doyle- BY M ATTORNEY Aug., 2, 1927. 1,637,558

. F. M. DOYLE SURFACE CONDENSER AND METHOD Filed Sept. 15, 1926 '3 Sheets-Sheet 3 llll'l'l-lllllllllllllll INVENTOR I Earl/1:11.90 [6 M ATTORNEY I Patented Aug. 2, 1927.

FRANK M. DOYLE, OF BRO OKLYN, NEW YORK.

SURFACE CONDENSER AND METHOD.

Application filed September 15, 1926. Serial No. 135,515.

perature rises due to absorption of heat from the steam being condensed, and consequently the cooling water leaving the condenser is at a considerably higher temperature than the.

entering cooling water. It is the general practice in the art to so construct and operate condensers that the entering steam immediately strikes the warmest portion of the cooling tubes; and the steam and air then move toward the coldest portion of the cooling tubes. The steam-air mixture, in'the condenser is thus reduced in temperature to a value approaching that of the incoming cooling water, which temperature is considerably lower than the temperature of the outgoing cooling water. In the prior art, this reduction of the temperature of the steam-air mixture in the condenser to the lowest possible value has been considered desirable for the purpose of increasing the density of the air and thus (as was thought) facilitating its withdrawal from the condenser by the vacuumpump. To obtain the greatest possible density of the air entering the vacuum pump, it is not uncommon in the art to pass the steam-air mixture through a separate air cooler after it has been withdrawn from the condenser.

This practice of so arranging and operating condensers that the steam-air mixture is cooled as much as possible and as much steam precipitated out as possible before being withdrawn from the condenser results in a large area of the cooling surface being surrounded by this cold dense air. Under such conditions, the air effectively shrouds the cooling surface, thus preventing the steam from coming into contact with the shrouded surface. This results in a very substantial proportion of the cooling surface being kept idle and hence the effective capacity of the condenser is correspondingly diminished. Furthermore, the condensate falling through this air zone becomes highly aerated and carries this undesirable air with the con- ."densed water back to boilers; unless the condensate is passed through a special de-aerating apparatus.

The condensers of the prior art usually have been so arranged that the condensation from-the steam is collected in the vicinity of the coldest portion of the cooling tubes, and accordingly the condensate is reduced to a relatively low temperature. Every degree the condensate is cooled, is' just one more degree it must be reheated. upon its return to the boiler, with a-corresponding increased consumption of fuel.

The principal object of the present invention is to reduce the shrouding with air of the cooling surface of a surface condenser.

Another object of the invention is to pro vide a condenser construction and method of operation which minimizes shrouding of the cooling tubes with air and minimizes the reduction in temperature of the condensate.

A still further object of the invention is to increase the capacity .and efiiciency of surface condenser organizations.

In accordance wnth the above and other objects of the invention, the difiiculties of the prior art are overcome by soconstructing and operating a surface condenser that the entering steam immediately comes in contact with the coldest portion of the cooling tubes and the'air and condensate are pumped from that portion of the steam s ace which embraces the warmest portion 0 the cooling tubes. To facilitate pumping of the air, it is passed through an air cooler after being removed from the steam space of the condenser, thus increasing its density to a maximum before it reaches the vacuum pump.

Fig. 1 of the drawings is a vertical sec- 7 tion, on line 1--1 of Fig. 2, showing diagrammatically a condenser embodying the present invention.

Fig. 2 is a diagrammatica-l cross sectional view taken on the line 22 of Fig. 1.

Fig. 3 is a more or less diagrammatic elevational view showing a second form of condenser embodying the present invention.

Fig. 4 is a sectional view partially in elevation taken on the line 44 of Fig. 3.

Fig. 5 is a plan view of the second form of condenser with part of the top broken away to show the inlet and outlet chambers for the cooling water.

Fig. 6 is a cross sectional view taken on the line 6-6 of Fig. 3. i

Fig.7 is a detai view showing the form The form of condenser shown in Figs. 1

and 2 comprises a cylindrical shell 1 traversed longitudinally by cooling tubes 2 which receive cooling waterthroug'h a header 4 and discharge the cooling waterthrougha second header 5. It will be noted that the header 4 has the greatest cross-sectional area, (measured at right angles to the direction of the incoming water) adjacent the inlet flange, and that the cross-section of the header decreases as the water flow path approaches the opposite side of the header. This construction provides a cross-section which accommodates the full water flow, as indicated by the arrows A, without the production of eddies which tend to slow up the water-flow. The header 5 is of a similar construction and the water flow is indicated by the arrows B. The cooling tubes 2 are coldest at the top and the upper end of the casing 1 is provided with a steam entrance 6 positioned so that the entering steam immediately comes in contact with the coldest portion of the cooling tubes. The tubes are arranged as indicated in Fig. 2, only part of the tubes being shown for the sake of clearness. The tube arrangement is such that the spacing is greatest on the side where the steam comes in and least on the opposite side, thus leaving the greateststeam space where there will be the greatest volume of steam. To allow the steam to approach the tubes from practically all directions, the shell is enlarged between points 8 and 9 (Fig. 1) to provide an annular passageway 10 (Fig. 2) between thecondenser shell and the outermost tubes;

Air in the condenser moves with the steam i towards the bottom of the condenser which by enclosing a nest of cooling tubes 2 in a vertical cylindrical casing or pipe 14. This pipe may be provided with bafiies 15 to give the air mixture a tortuous path through the cooler. The casing 14 which separates the air from the steam also shields the inclosed nest of tubes from the heat of steam. and

hence the full cooling efiect o f this nest is available for cooling the air.

' The condensate falls to the bottom of the condenser where the tubes 2 are the warmest,

and from there it is withdrawn through a conduit 17 The condensate in falling passes all the way through a steam zone and is not re-aerated as isthe case where the condensate falls through an air zone. Where the con- Idensate falls through an air zone and is cold when removed from the condenser, it carries a very large air content which often causes the hot well pump to become air-bound. The condensate from the presentcondenser'does not carry air and this pump trouble is obviated. The temperature of the condensate approaches the temperature of the outgoing cooling water as a limit and hence its temperature will always be somewhat higher than the highest cooling water temperature. Thus the condensate is returned to theboiler at the highest possible temperature, thereby conserving boiler heat.

Steam is not driven into a condenser chamber but merely flows forward because of the opportunity ofthe steam to expand therein and the function of the condenser is to change the steam into water. If the gas coming into the condenser were pure steam, then there would be but one material to'be removed, namely, the condensation water, and by removing this water, the condenser tubes would be working all the time at full capacity. In practice, however, a considerable volume of air comes into the condenser with the steam, due largely to leakage and also to aerated water used in the boilers.

This air does not condense but remains as a gas. Therefore, the removal of the condensation water does not clear the condenser.

Consequently, exhaust pumps are used to 'take out the moist steam-air mixture at a sub-atmospheric pressure and compress the same sufiiciently to discharge it into the atmosphere.

Heretofore in the art, condensers have been so designed that the moist air was not withdrawn from the condenser chamber at any zone, that is, there was no partition designed to separate the air mixture zone from the steam zone. The result has been that this gas, very largely air, formed a zone of its own in the condenser and submerged a large area of cooling tubes and decreased the effective operation of the condenser. The volumetric displacement of exhaust pumps, when in operation, is predetermined to remove the steam-air mixture from the condenser at a certain temperature, (which means a predetermined density and humidity). In the old practice, this usually was 10 below the, temperature of the steam in the condenser. Heretofore in condenser practice, the cooling water usually was led into the condenser at one endand steam at the other end, and the air was removed adj acent the end where the cooling water camein. It will be observed'that by removing the steam from the coldest portion of the condenser (which is at a less temperature than that for which the pump is calculated in order that the pump may work efiicient- 1y), thatthe air mixture will bank and fill the condenser chamber up to such a point on the condenser tubes. that the temperatu e balance, or rate of heat exchange, is such as to maintain the air mixture at the temperature for which the exhaust pump is calculated. This point will shift in the condenser chamber somewhat depending upon the temperature of the cooling water andabsolute pressure of the steam. Such portions of the condenser tubes as are within the air mixture zone are greatly impaired in their capacity to condense steam. Under the old practice, the coldest portions of the tubes were air locked, thus impairing the opera tion of the most effective part of the device. The condenser comprising the present invention obviates the difliculties heretofore encountered, in that the entire condenser chamber is a steam mixture zone, and the air mixture zone is mechanically separated from the condenser chamber proper by a partition. By bringing the cold water in at the end of the condenser where, the steam comes in and flowing both in the same direction, the water in the tubes increases in temperature toward the outlet end for the cooling water, and it will beobserved that the air does not have an opportunity to separate fromthe steam to form a. distinct fluid to blanket portions of the cooling tubes. As the steam condenses, the air mixture is kept hot and this hot air mixture is withdrawn,

from the condenser into the air conduit at such oint that the temperature of the gas is substantially equal to or slightly above the temperature for which the exhaust pump is designed and this is at a temperature closely below the saturation point of the steam in the condenser. Under these conditions, it will be observed thatthere is no layer of trapped air left, in the condenser. The air mixture that ordinarily is trapped in the condensers of the prior art in the resent construction is confined in the air column, which being of relatively small cross sectional area, causes this air mixture to flow through at a relatively high velocity into the exhaust pumps which discharge this air from the condenser into the atmosphere.

' In view of the fact that the entire condenser chamber operates upon steam and that the air mixture is withdrawn from a hot portion of the condenser chamber, the present condenser will operate efficiently, even though the cooling water may be fairly warm. This feature of the present invention makes this condenser particularly adaptable to warships Which mustbe able to put forth full power at all times and places, and since warships traverse all of the waters of the globe from the frigid zone to the tropical zone wherein sea water at accordingly varying temperatures is used for cooling water in the condensers, it is of utmost importance to have the power equipment eflicient under all conditions.

It will be noted that with the construction and operation just described, the air within- 'the steam space of the condenser is always kept at a temperature which is'higher than the highest temperature of the cooling water, and lower than the temperature of the steam, i. e. the air is taken from the condenser chamber at a temperature between these two, limits. This results in the air in the steam space being maintained at the least possible density, and hence its shrouding effect on the tubes is a minimum. This can be seen-more clearly from a comparison, under the same operating conditions, of a condenser constructed and operated in accordance with standard practice and the condenser of Figs. 1 and 2 operated as just described. For this purpose, typical oper- .ating conditions will be taken as follows:

temperature of incoming cooling water 70 degrees F., temperature of outgoing cooling water 96 degrees F., and pressure within the condenser of 1.2 pounds per square inch, absolute (27.5 inch vacuum).

With the usual commercial condensers, the steam enters adjacent the portion of the cooling tubes which are at a temperature of 96 degrees and the steam and air move toward the portion of the cooling tubes which are at a temperature of 70 degrees. The steam is condensing all the while and the air (saturated with moisture) is cooled to a temperature approaching that of the incoming cooling water, e. g. to within three degrees of the cooling water temperature or 73 degrees. The pressure in the condenser is 1.2 pounds per square inch, absolute, which pressure is the combined pressure of the air (P,) and the pressure of the moisture (P with which the air is saturated, i. e. P d-P 212 pounds per square inch, absolute]. Referring to a steam table, it is found that the pressure of saturated steam (F.,) at the temperature in question (73 degrees) is 0.40 pounds per square inch, absolute; and hence the pressure of the air alone is 1.2- 6.40:0.s pounds per square inch absolute. In other words, with the condensers of the prior art two thirds of the total pressure in the zone where the air is collected is air pressure and only one third of the pressure is steam pressure. Thus, the mixture in this zone is really saturated air in which the percentage of air is in great excess. This air mixture effectively submerges the tubes in the zone in quest-ion that little steam comes in contact with the tubes. The result is that in the zone the tubes are idle to such a large extent as to greatly diminish the total steam condensing capacity of the condenser.

Under the same conditions, applicants condenser operated in accordance with his method, prevents the submerging of the. tubes in the air. Assuming the same operating conditions, viz, temperature of incom- .square inch absolute. Referring to a steam"- ing cooling waterat 70 degrees F., .tempera- 'ture of outgoing coolingwater 96 degrees table, it-is found that at 99 degrees the pressure of the moisture of saturation is ounds per square inch,-absolute. Accordlngly, thepressure of the air alone in applicants case is 1.2O.92=O.38 pounds per square inch, absolute. This compares with the air pressure of .80' pounds per square inch, absolute with the prior art practice. It is seen, therefore, that in applicants case, the, density of the air in the zone of the condenser where it is collected is less than half the air density with the prior art practice; and hence the. submerging' action of the air is substantially eliminated.

In the condenser shown in Figs. 3 to 6 inclusive, there isa vertical cylindrical casing, designated as a whole by 21, composed ofupper section 22 and lower section 23 and adapted to' .be mounted by means of supporting arms 24 which may be integral with the lower section. There is a lower cover member 25, :1 water inlet and outlet header 26, and an upper cover member 27. These parts just enumerated may be secured together in. any suitable manner, as by bolting, riveting or welding. The interior of theshell 21 is dividedinto a two part steam space by a curved vertical partition 30, and one part ofthe steam space is traversed longitudinally by cooling tubes 31 while the other part is similarly traversed by cooling 'tubes 31'. The cooling tubes are arranged as shownin Fig. 6, only part of the tubes being shown for the sake of clearness.

' As shown in Fig. 5, the header 26, which is above the upper tube sheet, is provided with a curved partition 34 which corresponds in shape to the partition 30 and is directly above it. This partition 34 divides the header into an inlet chamber 35 and an outlet" chamber 36 for the cooling water.

The eooli'ngwater enters the inlet' chamber 35 through the conduit 38, passes downwardly through cooling tubes 31 to the cavity in the lower head 25, then upwardly through cooling tubes 31 to outlet chamber 36, and out through conduit 39. Steam to becondensed enters through passage 40 and immediately strikes the coldest portion of the .rection of flow of the cooling water.

roundin cooling tubes. The steam then passes downwardly around cooling tubes 31, in the di- As shown in Fig. 7, the partition 30 has one lower corner cut out at 42 as the steam passes .through this space and upwardly around cooling tubes 31.

An air cooler is incorporated in the condenser and consists essentially of a vertical conduit 43 which embraces a .nest of the cooling tubes 31. The warmest portion'of the cooling tubes is the upper ends of the 'tubes' 31" and the air cooler is in communication with the surrounding space through hole 44 (Fig. 7) in partition 30. This connection is shown in Fig. 4 at 45. After passing through the cooler, the air passes to the dry vacuum pump through exhaust passage 48 leadin to the exterior of the shell 21 nearlthe bottom thereof. The cooler may, of course, be provided With baflles such as shown in Fig. 1 in order to give the air a tortuous passage. Condensate collects in the. bottom of the casing 30 and is withdrawn through conduit 49.

-The operation of the condensers shown in Figs. 3 to 7 is essentially the same as that shown in Figs.- 1 and2. In both forms, the condenser is provided with an elongated steam space and thesteam flows longitudinally in this steam space in the direction of the flow of thecooling water. In the construction shown in Figs. 3 to 6, the cooling tubes 31' are in effect a continuationof the cooling tubes 31 .and the part of the steam 10o space surrounding the tubes 31 is a continuation of the part of the steam space surtubes 31. The tubes 31' with their surroun ing part of the steam space are merely folded up parallel to tubes 31, thus reducing the length of the condenser. The

cooling water which passes through the air cooler tubes, is still further used in the tubes 31'.

It is realized that the present invention 1 may be embodied in forms other than those particularly disclosed and hence it 1s desired that the present disclosure be considered as illustrative and not as limiting. The invention has been described with reference to the condensation of steam, with water as a cooling fluid because this is the usual case/However, it is obvious that any suitable cooling fiuid may be used and any vapor may be condensed. Accordingly, the term steam is used herein broadly enough to include any vapor and the use of the term water is not intended to limit the invention to any particular cooling fluid.

Having thus described my mvention, what I claim is:

1. A surface condenser comprising a shell within which is an elongated steam space, said shell being provided with a steam opening adjacent one end of the team space o 10 ing tubes traversing said steam space longi-' tudinally; means to circulate a cooling fluid through said tubes in the direction of flow of the steam, whereby the tubes are coldest at the entrance end of the steam space and warmest at the opposite end; means to purge the steam space of noncondensable gases by withdrawing them from that portion of the steam space which is adjacent the warmest portion of the cooling tubes; and means to cool said gases after they have been withdrawn from the steam space.

2. A surface condenser comprising a shell within which is an elongated steam space, said shell being provided with a steam open ing adjacent one end of the steam space to cause the steam being condensed to flow longitudinally along the steam space; cooling tubes traversing said steam space longitudinally; means to circulate a cooling fluid through said tubes in the direction of flow of the steam, whereby the tubes are coldest at the entrance end of the steam space and warmest at the opposite end; a conduit extending to a fluid pump from that portion of the steam space which is adjacent the warmest portion of the cooling tubes; and a cluster of cooling tubes in said conduit to cool noncondensable gases withdrawn from the steam space, and precipitate out its steam content.

3. A surface condenser comprising a shell within which is a steam space, cooling means traversing said steam space, said cooling means varying in temperature through the steam space and said shell being provided with a steam opening positioned to cause the entering steam to immediately come in contact with the coldest portion of the cooling means, means to purge the steam space of noncondensable gases by withdrawing them from that portion of the steam space which is adjacent the warmest portion of the cool ing means, and means to cool said gases after they have been withdrawn from the steam space.

4. A surface condenser comprising a shell within which is a steam space, cooling-moans traversing said steam space, said cooling means varying in temperature through the steam space and said shell being provided with a steam opening positioned to cause the entering steam to immediately come in con tact with the coldest portion of the cooling means, a conduit for noncondensable gases extending to a fluid pum from thatportion of the steam space which is adjacent the warmest portion of the cooling means, and means to cool the noncondensable gases drawn into said conduit.

5. A surface condenser comprising a shell within which is an elongated steam space, said shell being provided with a steam opening adjacent one end of the steam space to cause the steam being condensed to flow longitudinally along the steam space; cooling tubes traversing said steam space longitudinally; means to circulate a cooling fluid through said tubes in the direction of flow of the steam, whereby the tubes are coldest at the entrance end of the steam space and warmest at the opposite end; and'a casing enclosing a nest of the cooling tubes to shield them from the steam and form acooler for air and other noncondensable gases, said cooler having one end in communication with that portion of the steam space which is adjacent the warmest part of the cooling'tubes and the other end in communication with a fluid pump.

6. A surface condenser comprising a shell within which is a steam space; cooling tubes traversing said steam space, said tubes during the operation of the condenser varying in temperature through the steam space;

a casing enclosing a nest of the cooling tubes to shield them from the steam and form a cooler for air and other noncondensable gases, said cooler having one end in communication with that portion of the steam space which is adjacent the warmest part of the cooling tubes and the other end in comnmnication with a fluid pump.

7. In the operation of a surface condenser comprising a steam space traversed by cooling tubes which vary in temperature along their length, the method of minimizing shrouding of the cooling tubes with air and other noncondensable gases which comprises admitting the'steam to be condensed to that portion of the steam space which embraces thecoldest portion of the cooling tubes,'and withdrawing the noncondensable gases from that portion of the steam space which embraces the warmest portion of the cooling tubes. p

8. 'In the operation of a surface condenser comprising a steam space traversed by cooling tubes. which vary in temperature along their length, the method of minimizing shrouding of the cooling tubes with air and other noncondensable gases which comprises admitting the steam to be condensed to that portion of the steam space which embraces the coldest portion of the cooling tubes, withdraw-ing the noncondensable gases from that portion of the steam space which embraces the warmest portion of the cooling 10. In the operation of a surface condenser comprising a steam space traversed by cooling-tubes carrying a cooling fluid, the method of minimizing shrouding of the cooling tubes with air and other noncondensable gases which comprises maintaining the gases everywhere in the steam space at a temperature higher thanthat of the outgoing cooling fluid, withdrawing the gases from the steam space, and cooling the withdrawn gases.

11. A condenser having a condenser chamber, cooling water tubes traversing said chamber, an inlet header adjacent one end of said tubes, an outlet header adjacent the other end of said tubes, steam inlet means adjacent the inlet header for the cooling water, and an air outlet adjacent theoutlet header for the'cooling water.

. 12. The method of operating a surface condenser which method comprises admitting the steam and cooling water at the same.

end of the condenser chamber, and removing the air at the other end of the condenser chamber;

13. The method of operating a surface condenser which method comprises removing the air from the condenser chamber .adjacent the hottest portion ofthe conduits carrying the cooling water.

14. The method of operating a condenser to obtain a hot condensate, comprising inthe same end of the condenser and flowing said cooling water and steam in the same direction, and then removing the condensate from the condenser adjacent the hottest zone of the coolingwater.

15.-The method'of operating a' surface condenser to obtain a hot condensate, comprising introducing the cooling water and steam at the same end of the condenser, removing the air from the other end of the condenser where the cooling water is hot,

and maintaining the condensate while inthe condenserin contact with the steam.

16. The .method of operating a surface 'tr'oducing the cooling water and steam at I condenser to obtain the condensate ata high a tween the temperatureof' the steam in the condenser and the temperature of the outgoing cooling water.

ERANKMM. DOYLE,

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