US1769746A - Condensing apparatus - Google Patents

Description

July 1, 1930.

G. M NEILL CONDENSING APPARATUS Filed June 1923 2 Sheets Sheet l ooo0 0 00000c 000000 000000 000 00 0000000 0 0o0000o0o00oo o oooooooooowmm 00000000000 00000000000 O O OOOOOOOOOul 000000000000 00000000 0 0 INVENTOI? WITNESSES a- 2 Sheets-Sheet 2 00 0 d 00000 00 0 00 00000 0 00000000000 e000 0000 000 0/l 0000000000000 00 000 00000000 000000000000 00000000000 000000000000.. 0000000000 000 000000 G. L/M NElLL CONDENSTNG APPARATUS Filed June 4, 1923 FIELEI.

July 1, 1930.

w/wvssszs Patented July 1, 1930 UNITED STATES GEORGE L. MACNEILL, OF READING, PENNSYLVANIA CONDEN SING APPARATUS Application filed .Tune 4,

An object of this invention is to produce an improved apparatus for the purpose of conserving heat in connection with condenser installations.

A further object is to produce condensing apparatus in which new and improved means are employed for subjecting conden sate delivered from a condensing element of the apparatus to the heating action of fluid to be condensed, whereby the condensate is delivered from the installation at an .in-.

ed, while doing work in the prime mover,

to a pressure materially below atmospheric pressure. In order to obtain the highest efficiency possible, it is necessary to condense substantially all the. steam exhausted by the prime movers into the condensing apparatus, and at the same time subject the exhaust passages of the prime mover to substantially the entire reduction in pressure occasioned by the condensation of the steam exhausted from it.

temperature in the condensing apparatus which will insure complete condensation. The condensate delivered from the condenser is consequently at a low temperature, -substantially the temperature of the condenser,-and this occasions a loss in the over-all economy of the plant, since the condensate is ordinarily delivered to the boilers as feed water and considerable heat energy is required to raise its temperature and reconvert it into steam.

It is usual practice to employ surface condensers, particularly where water for boiler feed is scarce. or of a poor quality. It is also usual practice to deliver the condensate This necessitates maintaining a 1923. Serial No. 643,183.

delivered from the condensers directly to the boilers or the feed waterheaters. In any event, heat is conserved by increasing the delivery temperature of the condensate as it leaves the condenser and particularly where the heat for so increasing the temperatureis derived from steam to be condensed.

Various attempts have been made to conserve heat in this manner. surface condensers have been so constructed that exhaust steam from the prime mover, enters the condenser below the nest 01" condensing tubes and flows upwardly between the tubes toward an air oiftake port located at or adjacent to the top of the nest. With such a construction the condensate formed on the tubes must, of necessity, fall through the incoming steam, in dropping to the bottom ofthe condenser. In so doing it takes up heat from the steam andv is delivered from the condenser at a temperature. approximately rthat of the steam. Such con-- densers have the advantage of delivering condensate at a relatively high temperature, but they occasion a loss in vacuum at the exhaust port of the prime mover.

The exhaust passages between the prime mover and the condensers are necessarilylong and somewhat circuitous. The steam issuing from the exhaust port must therefore not only pass through the long exhaust passage but its direction of flow must be reversed. This occasions pressure losses and the loss of vacuum at the exhaust port of the prime mover more than over'balances the gain occasioned by the partial heating of the condensate.

This will be made more apparent when it is remembered that a high vacuum is only effective in increasing the eficiency of the prime mover, when it is effectively applied to the low pressure work passages of the prime mover. The object of all condensing apparatus is to maintain the highest possible vacuum' at the exhaust port of the engine served; consequently, any apparatus which reduces the degree of vacuum obtainable at this point is objectionable.

As the demand for high vacuum increased with the modern development of. the steam For example, 1

l'Oll turbine, the type of condenser above de-- scribed became obsolete, primarily because H the hot well of the condenser for the purpose of heating the condensate collecting therein. This has been found to be inefi'ective and the analysis of the operation of a j n surface condenser will demonstrate the im- 7 practicability of such a structure.

In surface condensers it is necessary to maintain a high steam velocity through the tube nest, in. order to obtain an eflicient heat transfer from the steam to the water cir culating through the tubes. Such a velocity of steam flow can only be maintained by maintaining an adequate difference in pressure between the point of steam admission In to the tubes stop of tube nest) and the t of comp ete condensation within the neat (bottom of the nest). It follows that the pressure in the lower part of the condensers shell, including the hot well, must a be lower than the art of the shell adjacent the steam inlet. The pressure drop through the tube nest in a well designed condenser may bein the vicinity of 1/10 of an inch of mercury. A reference to the steam tables showethat with a condenser maintaining a vacuum of 29 inches of mercury (reference toltw inch barometer) at the exhaust port or a turbine, the tem erature of the steam atthis int is 793 for a 1/10 inch drop a throng the tubes, 9. reference to the steam tables shows that the condensate leaving the condenser cannot exceed 7 5.8 F., where exh aust steam is by-passed around the tube nestto the hot well, for the purpose of heata ing the condensate.

Moreover, such a condenser will operate for a short time only in heating the feed water to this temperature. This is apparout when it is considered that the air content of the mixture of steam and air in the lower part of the condenser is obviously higher than at the entrance or inlet port of the, condenser. The steam exhausted from q the prime mover is under usual conditions practically air-free and during its passage through the tube nest is practically all condensed. In addition to this, air leaking into the condenser is carried by the steam flow M to the lower part of the shell, and of necessity increases the ratio of air to steam at the hot well. r j j This steam and air mixtureis heavier, per unit of volume, than the substantially airfree steam delivered from the by-pass, and consequently the hot well will soon become air-bound, thereby'preventing further flow of steamthrough theby-pass into the hot through the steam takes up heat from the steam and is delivered from the condenser at approximately the temperature of the incoming steam. It has also been proposed to construct condensers so that steam is led to a heating chamber, independent of the tube nest and into which condensate from the nest dows. Both of these arrangements of apparatus are more or less inefl'ective; and they are both objectionable because they are expensive to construct and necessitate numerous steam directing bafiies within the condenser shell. Such baflles are objectionable from the standpoint of cost and in addition condensers so constructed function properly, only so long as the bullies resist deterioration and remain tight and in osition within the condenser shell. An 0 ject of m invention is to accomplish a substantial eating of the condensate, and at the same time overcome the objectionable features of the apparatus to which reference has been made.

An object of my invention is to produce simple, cheap, accessible and durable condensing apparatus in which means are emloyed for raising the condensate to the ighest possible temperature by subjecting it to the heatin effect of exhaust steam, to be condensed, without reducing the efiective vacuum at the exhaust port of the prime mover.

In accomplishing this and the previously mentioned objects, I employ apparatus provided with means for subjecting the condensate to the heat action of steam of the highest temperature and air-free uality existing within the condenser under t e various operating conditions encountered. An advantage of apparatus embodying my invention is that it improves the economy of the main condensing unit by reducing the volume of steam delivered to it under normal operating conditions.

In the drawings accompanying and forming a part hereof, Figure 1 is a transverse sectional View along the line 11 of Fig. 2, Fig. 2 is a side elevation of the apparatus shown in Fig. 1, Fig. 3 is a transverse sectional view corresponding to Fig. 1, showing a modified form of apparatus,and Fig. 1 is a sectional view of the jet condenser shown in Fig. 3 and illustrates a detail of the apparatus.

In the apparatus illustrated, the main condenser includes a shell 5 provided. with a steam inlet port 6 and a condensate delivery port which communicates directly with a hot well 7. The shell is also provided with the usual offtake port 8 through which air or non-condensible vapors are withdrawn from the interior of the condenser. The cooling tubes 9 are arranged within the shell in the usual manner, and extend longitudinally thereof with their ends in open communication with water boxes 10 and 11. As illustrated, the tubes are preferably arranged in two passes so that the cooling water entering the water inlet 12 passes from the divided water box 10 through the lower bank of tubes to the water box 11. c It is thenreturned through the upper bank to the upper compartment of the water box 10 from which it is discharged through the water discharge port'13. The air oiftake port 8 is preferably shielded by a baffle 14 as is customary.

A novel feature of this apparatus is the provision of a steam delivery port 15 at a 7 point within theshell between the inlet port 6 and the nest of tubes 9. As shown, this port communicates with a steam delivery passage 16 which forms a means of communication between the steam inlet port 6 and a jet condenser 17, which may be of bining tube or mixing chamber 27 through the series of ports 27 The combined cooling water and condensate issuing from the condenser 17 is delivered to a tank, heater or other apparatus by a pump 19, and is eventually delivered to the boilers in the usual manner.

As illustrated, the hot well .7 is connected to the inlet of the pump 18 by piping 21 and the outlet of the pump is connected to the water inlet of the condenser 17 by means of piping 22. Piping'23 establishes communication between the outlet or water discharge port of the condenser 17 and the inlot of the pump 19. As illustrated, I preferably employ a branch pipe 2% between the pipe 21 and 23 and also employ valves 25 in the piping so arranged that connnunication between the hot well 7 and the pump 18 may be cut off, and the hot well may be placed in direct communication with the inlet of the pump 19. Communication may also be cut off between the condenser 17 and the pump 19 and between the pump 18 and the condenser 17. "With this arrangement of valves, the condenser 17 may be shut down without interfering with the operation of the main condenser, and without interrupting the operation of the engines or turbines served by the condensing apparatus.

In order to establish and insure steam flow from the main'condenser through the port 15 and to the auxiliary condenser 17 it is necessary to maintain a pressure within the condenser 17 which is less than the pressure at the inlet port 6 of the main condenser. I preferably accomplish this by venting the condenser 17 in such a way as to insure a sufficient drop of pressure through it to maintain the desired steam flow. As illustrated in Fig. 1, the interior of the condenser 17 may be placed in communication with a zone of low pressure in the main condenser by means of a piping 26. As shown, this piping communicates with the condenser 17 at a point immediately below the combining tube 27, and with the main condenser at a point adjacent to the air oiftake port 8 or at a point near the bottom of the condenser, subject to the cooling effect of the lower and cooler bank of tubes. The piping 26 is, of course, provided with a valve 28 adapted to be closed when the condenser 17 is not in operation. The venting of the condenser 17 may be accomplished by employing a separate vacuum-producing element such as an air ejector or other air removal apparatus, or it may be connected to an air cooler 30, in the manner illustrated in Fig. 3.

In Fig. 3, I have illustrated an arrangement of apparatus in which the main condenser is provided with an air cooler 30, the air inlet of which communicates with an air ofltake port formed in the shell 5 of the main condenser and the air outlet port of which communicates with a steam ejector 32 or other air or non-condensable fluid removal apparatus.

The condenser 17 of Fig. 3 is of materially different type from the auxiliary condenser of Figs. 1 and 2 and is illustrated in detail in Fig. 4.

As shown, the condenser 17 is provided with a water inlet port which receives condensate from the main condenser through piping 22. This port communicates directly with'an overflow chamber 34 so arranged that it delivers water in the form of a curtain made up of a mass of separate drops or spray, to the uppermost pan of a series of drip'pans 35. The pans are so arranged inc they retain the water in the condensing chamber a sufficient period of time to insure the desired heat transfer from the steam to the water, and at the same time occasion a. flow of such character as to insure a comletermixing of the steam and the water.

This is accomplished by so locating and the pans that they produce a seo cascades composed essentially of separate drops or spray and forming a relatively curtain which intervenes between the steam inlet ort and the air ofl'take port 36 of con ensing chamber. The edge of each an on the steam inlet port side of the pan, orm an overflow edge and each of the upsler pans is also provided in its bottom W1 a seriesof water discharge apertures which are so located with relation to the discharge ed e as to form a continuous stream such as ascribed. The lowermost pan oi the series need not be provided with the apertures in its bottom, but it is preferably so. located that the curtain of rain or se arate drops flowing from it, contacts with a of the condensing chamber and intervanes between the steam outlet port and the water delivery port, as well as between the inlet port and the air otltake port. Such an arrangement of apparatus insures complete condensation of the steam and consequently adequate heating of the condensate delivered from the hot well of the main condenser.

The pi 23 delivers the heated condensate to t e pump 19', which is similar in function to the pump 19 in Figs. 1 and 2. The piping arran ement is substantially similar to that disc osed in Fig. 1.

In Fig. 2, I have illustrated the pumps 18 and 19 as motor driven, each pump being shown directly connected to a separate mo- 1301* 31. It will be apparent that these pumps ma be directly connected so that they may driven by a single motor or they may be enclosed within a sin le hous- It will also be apparent t at both the surface and the jet condensing elements together with the connecting passages, may be incorporated within a single shell for the purpose of simplifying the operation of installing the combined apparatus.

The operation of the apparatus is as follows: Exhaust steam delivered to the main condenser enters the port 6. The major portion of this steam passes downwardly around the tubes 9 of the main condenser where it is condensed. By maintaining a drop in pressure through the condenser 17, or in other words by maintaining a pressure at the outlet of the combining tube which is less than the pressure in the passage 16, a substantial quantity of exhaust steam will pass to the condenser 17. It will be appareat that by proportioning the areas of the in port and the passage 16, the quantity of steam flow-to the auxiliary condenser may be made to bear a definite proportion to the flow of steam flow to the main condenser and consequently the amount of steam condensed by the auxiliary condenser under normal operating conditions may be accurately predetermined. It also follows that the delivery temperature of the condensate may be accurately predetermined for normal operating conditions.

t will be apparent that the condensate entering the hot well 7 of the main condenser will be substantially at the temperature corresponding to the vacuum maintained in the lower part of the main condenser and that consequently it will be colder than the incoming steam. By employing this condensate as cooling liquid in the auxiliary condenser, Iobtain the double advantage of delivering condensate at a materially increased temperature, and at the same time condensing the steam delivered to the auxiliary condenser without the necessity of cmploying additional cooling water or additional cooling surface in the main condenser. My main ob'ect, however, is to deliver the condensate creased temperature and to thereby conserve heat since, under ordinary operating conditions, the condensate is delivered almost immediately to the boilers, or to heaters, so that any saving in heat results in a direct gain in efiiciency of the plant.

Another advantage of my invention is that it accomplishes de-aeration of the condensate. This results from the fact that the hot condensate leaving the jet condenser while in the form of spray is subjected to a vacuum.

Another feature of my invention is that it increases the efiiciency of the condensate pump 19 in that it materially increases the suction head of that pump without the necessity of increasing the head room for the installation of the apparatus.

It will be apparent from the drawings that the total head against which the condensate pumpin apparatus dischar es is the same as in ordinary installations w ere a single pump element is em loyed. When it is understood that the con ensate pump discharges the condensate through the closed feed water heaters, with a resulting high discharge head or back pressure, 1t will be apparent that the efliciency of the pump is to a great extent dependent u on the static head over the suction side of t e pump. By employing the apparatus illustrated, the suction head of this pump is materially increased without the necessity of increasing the head room. This is apparent from the drawings, since the suction head of the pum 18 corresponds closely to the suction heah ordinarily obtained in connection with the condensate discharge pump, and a comparirom the installation at an in-' son of the suction head of this pump with the suction head of the pump 19 clearly discloses the fact that the latter pump has the advantage of a materially increased suction head and that it will, therefore, operate with greater efliciency than similar pumps in ordinary installations.

While I have illustrated what I now consider to be the preferred embodiment of my invention, it will be apparent that various changes, modifications, additions and omis sions may be made in the apparatus illustrated without departing from the spirit and scope of the invention as set forth by the appended claims.

What I claim is:

. 1. In combination in a condensing apparatus, a surface condenser having a hot well and a jet con lenser, having a fluid inlet port, a condensate discharge port, and a cooling water inlet port, means for delivering condensate from the hot well of the surface condenser to the cooling water inlet port of the jet condenser, means for delivering fluid to be condensed from the source of supply of the surface condenser to the fluid inlet port of the jet condenser, means for breaking the flow of cooling water within the jet condenser into a mass of separate drops, and means communicating with the jet condenser at a point between the cooling water inlet port and the condensate discharge port for withdrawing air and noncondensible fluids fromsaid jet condenser.

2. In a condensing apparatus, a surface condenser, having a fluid inlet port, a hot well provided with a condensate discharge port in combination with a jet condenser elevated above said hot well and having a fluid inlet port, a cooling water inlet port, and a condensate discharge port, means for delivering fluid to be condensed to the fluid inlet ports of both condensers, means for elevating condensate from said hot well and delivering it through the cooling water inlet port of said jet condenser, and means for venting the interior of the jet condenser to vacuumat a point between said cooling water inlet port and said condensate delivery port.

3. In a condensing apparatus, a surface condenser having a hot well, a jet condenser elevated above the hot well of the surface condenser and having a fluid inlet port communicating with the fluid inlet port of the surface condenser, a cooling liquid inlet port, and a condensate discharge port, means for elevating and delivering condensate from the surface condenser to said cooling water inlet port, means within the jet condenser for breaking the flow of cooling liquid so delivered into a curtain of separate drops intervening between said fluid inlet port and said condensate discharge port, and means for venting the interior of inlet port, a hot well, and a condensate d scharge port, a jet condenser elevated above the said hot well, and having a fluid inlet port communicating with the fluid inlet port of said surface condenser, a cooling liquid inlet port, and a condensate discharge port, means for elevating and delivering condensate from said condensate discharge port of the surface condenser to the cooling liquid inlet of the jet condenser, means for breaking theflow of cooling liquid within the jet condenser into a divided flow intervening between the fluid inlet and the condensate discharge ports of said et condenser, and means for subjecting the interior of said jet condenser to vacuum pressure for producing and maintaining a flow of fluid through said divided flow of condensate.

5. A condensing apparatus, comprising a surface condenser having a hot well, a jet condenser having its mixing chamber elevated above the hot well of the surface condenser, means for delivering exhaust steam to both said condensers, means for delivering condensate from the hot well of the surface condenser to the mixing chamber of the jet condenser, and means for producing and maintaining, a flow of steam to the mlxlng chamber of the jet condenser, and means for withdrawing condensate from the jet condenser.

6. A condensing apparatus comprising a surface condenser having a fluid inletport, a condensate discharge port, and an air ofltake port, in combination with a jet condenser elevated above said condensate dis-.

charge port and having a fluid inlet port, a condensate discharge port, and a combining tube between said fluid inlet port and said condensate discharge port, means for elevating and delivering condensate from the discharge port of the surface condenser through said combining tube, and means intermediate said combining tube and the condensate discharge port of the jet condenser for maintaining substantially the same degree of vacuum in said jet condenser as in said surface condenser.

7. A condensing apparatus comprising a surface condenser having a hot well, a jet condenser elevated above the hot well of 'the surface condenser and receiving steam to municating with said jet condenser on the side of said combining tube for mamtami substantially the same vacuum within'sai jet condenser as in said surface Aoondenseqand a ump for withdrawing condonsate from sand jet condenser.

' In testimony whereof I have hereunto subscribed my name this 3rd day of Ma 1923.

GEORGE L. LIACN ILL.

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