US2114873A

US2114873A - Elastic fluid surface condenser

Info

Publication number: US2114873A
Application number: US21891A
Authority: US
Inventors: Jr Bevis P Coulson
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1935-05-16
Filing date: 1935-05-16
Publication date: 1938-04-19
Anticipated expiration: 1955-04-19

Description

April 19, 1938. B. P. couLsoN, JR 2,114,873

ELASTIC FLUID SURFACE CONDENSER Filed May 16, 1955 Fig.3

Inventor". Bevis F CoLUsovm, J

is AttOTTjey.

' Patented Apr. 19, 1938 ELASTIG FLUID SURFACE CONDENSER,

Bevis P. Coulson, J12, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application May 16, 1935, Serial No. 21,891

3' Claims.

The present application is a continuation in part of my application Serial No. 712,538, filed February 23, 1934, relating to elastic fluid surface condensers, particul-arly. mercury vapor '5 condenser and condenser boilers, although it. is not necessarily limited thereto. The invention is of special importance in connection with surface type mercury condenser boilers in which mercury vapor is condensed by a medium such 10 as water which in turn is evaporated.

Vapor exhausted by elastic fluid turbines contains air and other non-condensable gases leaking past packings into theinterior of turbines exhausting into condensers. The amount of such 15 gases is often considerably increased dueto air leaking from theatmosphere into the condenser. These .non-condensable gases in surface cond'ensers reduce the heat transfer from the vapor throughthe tubes to the cooling medium by forming blankets on the tubes, an eifect known as blanketing of the tubes. To overcome this drawback, it is necessary to provide means for removing or extracting, non-condensable gases from the condensers. 7

One object of my invention is to provide an improved construction and arrangement of mercury condensers and the like whereby the air and other non-condensable gases contained in the mercury vapor or like elastic fluid to be condensed are readily removed and the efficiency of the condenser thereby substantially increased.

Another object of my invention is to provide an improved arrangement of condensers in which the ,floW of non-condensable gases through the conduit for discharging condensate is substantially eliminated.

- This is accomplished in accordance with my invention by the provision of means for extracting the non-condensable gases at the region or regions where the final condensation takes place.

I have found that the relative amount of air or other non-condensable gases contained'in the mercury vapor increases with increasing condensation and reaches a maximum in those regions 45 of the condenser in which the final condensation takes place. Therefore, I provide air-extracting means which may be in the form of a tube or tubes with a plurality of openings located at points of minimum heat concentration due. to

50 the blanketing of the condenser tubes by the non-condensable gases.

The second object of my invention is accomplished by the provision of means reducing the flowaofnon-condensablestowards the outlet for 55 the condensate;

For a better understanding of what I believe to be novel and my invention, attention is directed to the following description and the claims appended theretoin connection with the accompanying drawingwhich forms a part of my specification. v

In the drawing, Fig. 1 is a sectional view of a condenser embodying my invention; Fig. 2 is a cross-section along line 22 of Fig. 1; Fig. 3 is a sectional view of a modification of my invention; and Fig. 4 is a sectional view, partly broken away of another modification of my invention.

The surface condenser shown by way of example in Fig. 1 is a condenser boiler for con- '15 densing mercury vapor and evaporating water of the type in which a single bank of tubes communicating with a header or tank for receiving coolingmedium is provided. It comprises a lower tank Hi and an upper tank or header H having '2 flanged portions united by bolts l2. Depending from the upper tank H are a plurality of deadend tubes l3 communicating with the upper tank. The lower tank It! has a flanged opening M for receiving mercury vapor to be condensed. A sump l5 having a discharge conduit it for mercury liquid is connected to the bottom of the lower tank. The upper tank II has an inlet conduit If for conducting water to the tank and an outlet conduit l8 for discharging steam. During operation, mercury vapor is passed across the outer surfaces of the depending tubes I3 whereby its heat content is transferred to the water contained in the tubes l3, effecting condensation of the mercury and evaporation of the water. The mercury condensate collects in the sump I5 and is discharged through. the conduit Hi. The steam generated in the depending tubes l3 flows into the upper tank I l and is discharged through the conduit IS. The direction of flow of 4D the mercury vapor is indicated by arrows in Fig.

2. The arrangement of the depending tubes is such as to obtain the best cooling effect at a mini mum resistance toward the flow of mercury vapor.

From a consideration of Fig. 2, it will be readily seen that the relative amount of non-condensable gases increases along the path of the mercury vapor, reaching a maximum value at points where the final condensation takes place. The increasing content of air and other noncondensables in the mercury vapor causes an increased blanketing of the tubes l3 and thereby reduces considerably the heat transfer through these tubes. To reduce the blanketing of the tubes in order to increase the heat transfer, I provide in accordance with my invention means for extracting non-condensable gases wherever the amount of these gases reaches a certain value. Preferably, I provide an air-extracting tube extending over a substantial area of minimum heat concentration due to blanketing of the tubes by the non-condensable gases. In the type of condenser shown in the drawing the region of minimum heat concentration is considerably spaced from the outer condenser wall. It is located intermediate the center of the cylindrical condenser casing and the wall portion of the casing opposite the inlet opening [4. In the present instance I have shown an extraction tube l 9 having a plurality of openings through which the non-condensable gases are withdrawn. The tube i 9, as pointed out above, is located in a region of minimum heat concentration and in the type of condenser shown in the drawing is surrounded by or interspaced between cooling tubes. Its upper end is connected to the bottom 2| of an extraction chamber 22 having a V-shaped wall 23 fastened to the lower tank or casing I0 by welds 24. The non-condensable gases are removed from the chamber 22 by any suitable means through an opening 25 in the outer tank or casing l0.

It is desirable to extract air and non-condensable gases at a uniform rate along the entire length of the extraction tube. To this end I provide the tube with a plurality of openings having an opening area per unit tube length decreasing in the direction of the tube outlet, that is, the opening area over a unit length near the bottom of the tube (Fig. l) is larger than over a unit length near the top or discharge end thereof. The larger opening area near the bottom causes a somewhat higher pressure to exist within the lower portion of the extraction tube than within the upper portion thereof, resulting in flow of gases from the bottom portion of the tube towards the upper portion, that is, towards the discharge end thereof.

Referring now to Fig. 3, where I have shown a modification of my invention, the condenser boiler comprises a lower tank and an upper tank 3| corresponding to .tanks l0 and H respectively of Fig. 1. The lower tank has an inlet opening 32 for mercury vapor to be condensed and its bottom is connected to a sump 33 having a conduit 34 for discharging condensed mercury. The upper tank 3| has an inlet opening 35 through which water is conducted into .the tank and a conduit 36 for discharging steam. A plurality of depending dead-end tubes 3'! projecting into the lower tank 38 are connected to the upper tank 3| for receiving water therefrom, the water being at least partly evaporated in the tubes and expelled into the upper tank. A tube or channel 38 corresponding to the tube I9 of Fig. l is provided in the lower tank 30, extending over a considerable region of minimum heat concentration, that is, a region in which the content of non-condensable gases in the mercury vapor has reached a maximum value. In the present instance the tube 38 has a closed upper end and projects through the bottom of the lower tank 30. The tube has a plurality of openings 39 which are more closely spaced at the upper end of the tube than near the lower tube portion in order to obtain uniform extraction along the tube. In the present instance I have shown means for removing mercury vapor which may be carried along by the non-condensable gases into the tube 38. This means comprises an auxiliary condenser 40 having an outer casing 4| forming two headers 42 and 43. The headers are connected by a plurality of cooling tubes 44. A lower portion of the tank 4| is connected to a sump 45 having an outlet 46 for non-condensable gases and a discharge conduit 41 for mercury. The headers 42 and 43 are connected to

conduits

48 and 49 respectively for receiving and discharging water, the tube 49 being connected to the inlet opening 35 of the upper tank 3|. During operation, mercury vapor, as it flows through the inlet 32 of the lower tank across the depending tubes 31, is condensed, the condensate being discharged through the sump 33 and its discharge conduit 34. The non-condensable gases and a certain amount of mercury vapor is withdrawn from the lower tank 30 through the extraction tube 38 and flows into the auxiliary condenser. Water is conducted through the conduit 48 to the header 42 of the auxiliary condenser, whence it flows through the cooling tubes 44 into the right-hand header 43 of the auxiliary condenser. From the header 43 the preheated water is conducted through conduit 49 into the upper tank 3| and its tubes 31 in which it is evaporated to be finally discharged through the conduit 36. The mixture of noncondensable gases and mercury vapor discharged from the extraction conduit or tube 38 flows across the tubes 44 of the auxiliary condenser whereby the mercury condenses and collects in the sump 45 whence it is withdrawn through the conduit 4'1, the non-condensable gases being removed by any suitable means, such as pumps or the like (not shown), through the conduit 46.

During operation of condensers of the type described above, I have found that the non-condensables have a tendency to flow partly towards the outlet conduit for the condensate, in which case they are discharged partly together with the condensate and in the case of a mercury power plant flow into the boiler. The presence of noncondensables in the form of air in the boiler is undesirable because air causes oxidation of the boiler walls which reduces considerably the heat transfer from these walls and consequently the boiler output, moreover endangers the operation of the boiler in that oxidized boiler surfaces lead to hot spots.

In accordance with my invention I provide two means for reducing the flow of non-condensables into the outlet for the condensate. The first means consists in a particular location of the outlet conduit for condensates and a special relation between the location of this outlet and the location of the air removal means. As shown in Fig. l of the drawing, the sump l5 forming an outlet for the condensate is considerably spaced from the air removal conduit l9. More specifically, the sump l5, that is, the outlet conduit for the condensate, is connected to a region of the condenser in which the heat concentration is a maximum, whereas the air removal conduit I 9, as explained above, is disposed in a region in which the heat concentration is a minimum. From another viewpoint, the discharge conduit for condensate is connected to a region of the condenser in which the partial pressure of condensables, in the present instance mercury, is a maximum, that is close to the opening l4 for admitting vapor to the condenser, whereas the air removal means is disposed in a region in which the partial pressure of the condensables is a minimum and the partial pressure of the non-condensables a maximum, in the present instance, at a considerable distance away from the inlet I4 for admitting vapor to the condenser. However, it is to be noted that this considerable distance between the inlet I4 and the air removal conduit I9 is less than the diameter of the tank because the location of the region of maximum partial air pressure is not diametrically opposite the inlet I4. The second means for preventing flow of noncondensables into the discharge conduit for condensate comprises the provision of a deflector or like auxiliary means for creating an artificial draft from the region to which the discharge conduit for condensate is connected to the region in which the air removal conduit is disposed. As shown in Fig. 1, this means comprises a deflector 5!! suitably fastened to the wall of the condenser for deflecting a portion of the vapor flowing into the inlet M towards the bottom of the condenser. The deflected vapor flows across the connection of the casing with the sump I5 towards the air removal conduit I9. The direction of flow is indicated by an arrow 5!. Thus the provision of the deflector 50 causes the creation of an artificial draft from the inlet I4 across the connection with the sump I5 towards the air removal conduit I9. This draft reduces or prevents the formation of a draft in opposite direction. The bottom of the casing ID, as shown in the drawing, forms a channel inclined towards the left with the sump I 5 connected near the left-hand end or lowest portion of this channel.

The arrangement for preventing the flow of non-condensables from the region of minimum heat concentration into the discharge conduit for condensate is similar in Fig. 3 but instead of a deflector I provide in Fig. 3 means including a conduit 52 for extracting vapor from the condenser inlet 32 and discharging vapor across the inlet sump 33 in the direction of the air removal conduit 38. The direction of flow across the connection of the discharge for condensate is indicated by an arrow 53. As explained before, the discharge conduit for condensate is connected to a region in which the partial pressure of noncondensables is a minimum, whereas the air removal conduit 38 is disposed in a region in which the partial pressure of the non-condensables is a maximum and the partial pressure of the condensables a minimum.

The arrangement shown in Fig. 4 includes a tank 55 corresponding to the tank I 0 of Fig. 1. The tank has an inlet 56 and a plurality of cooling tubes 51 corresponding to the tubes I3 of Fig. 1. Means including a perforated conduit58 corresponding tothe conduit I9 of Fig. 1 are provided for extracting non-condensable gases. The conduit 58 is interspaced between the cooling tubes 51 and disposed in a region in which the partial pressure of the non-condensable gases including air reaches a maximum. A sump representing in substance a conduit 59 for discharging condensate mercury is connected to a central portion of the bottom of the tank 55. The arrangement shown in Fig. 4 is provided in accordance with my invention with an air removal conduit disposed in a region of maximum partial pressure of air and other non-condensable gases as is the case in the arrangement of Figs. 1 to 3. In contrast to the latter arrangements the condensate discharge means is not connected to a portion of the tank near the inlet for vapor to be condensed, that is in a region in which the partial pressure of the non-condensable gases is a minimum. Whereas my invention may be used in the form shown in Fig. 4, I prefer the arrangements shown in Figs. 1 to 3.

Having described the method of operation of my invention, together with the apparatus. which I now consider to represent the best embodiments thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An elastic fluid surface condenser including a tank having an inlet for elastic fluid to be condensed and an outlet for condensate, cooling means including a plurality of tubes projecting into the tank, and means for extracting air and other non-condensable gases from the tank, said means comprising a tube with a plurality of openings extending over a substantial portion of the region of minimum heat concentration in the tank, the opening area of said openings per unit tube length being reduced towards the outlet of the tube to cause uniform extraction along the entire length of the tube.

2. An elastic fluid surface condenser including means comprising a perforated conduit disposed within the condenser for extracting air and other non-condensable gases, a conduit connected to the condenser for discharging condensate, and means. for creating an artificial draft across the connection of said last named conduit with the condenser towards the perforated conduit of the air removing means.

3. An elastic fluid surface condenser including means for extracting air and other non-condon sable gases from the condenser, said means being disposed in a region of minimum heat concentration, a. conduit connected to the condenser for discharging condensate, and means including a deflector for causing a draft from the connection of the condenser with said conduit towards the air removal means.

BEVIS P. COULSON, JR.