US2168902A

US2168902A - Surface condenser

Info

Publication number: US2168902A
Application number: US218115A
Authority: US
Inventors: John F Grace
Original assignee: Worthington Pump and Machinery Corp
Current assignee: Worthington Pump and Machinery Corp
Priority date: 1938-07-08
Filing date: 1938-07-08
Publication date: 1939-08-08
Anticipated expiration: 1956-08-08

Description

Aug. 8, 1939 J. F. GRACE 2,168,902

SURFACE CONDENSER Filed July 8, 1958 6 Sheets-Sheet 1 John F. Grace l VENTOR ATTORNEY Aug. 8, 1939 J F,- GRACE 2,168,902

SURFACE CONDENSER Filed July 8, 1938 6 Sheets-Sheet 2 I4 12 [I8 F 1 I 5 I '"':\-L

INVENTOR ATTORNEY 6 Sh eets-Sheet 3 l VENTOR ATTORNEY Aug. 8, 1939 J. F. GRACE SURFACE CONDENSER Filed July 8, 1938 John E Grace Aug. 8, 1939 J F. GRACE SURFACE CONDENSER Filed July 8, 1938 6 Sheets-Sheet 4 m m G El n m J INVENTOR ATTORNEY Aug. 8, 1939 J. F. GRACE 2,168,902

SURFACE CONDENSER Filed July 8, 1938 6 Sheets-Sheet 5 ATTORNEY Aug.-8, 1939 J. F. GRACE SURFACE CONDENSER Filed July 8, 1958 6 Sheets-Sheet 6 QOOOOOOOOOOD 0 O O O O O o 000 00 O O w o w o ooooooooooob O O O G John F. Grace lNVENTOR ATTORNEY Patented Aug.',-8, l 9 9 sUarAcE CONDENSER John F. Grace, 'Arlington, -N. 1., assignor to Worthington Pump and Machinery Corporation, Harrison, N. J., a corporation of Delaware Application July 8, 1938, Serial No. 218,115

15 Claims.

This invention relates to surface condensers for condensing steam in power plants, and more particularly to a method and apparatus for regulating the absolute pressure at a given or predetermined point in the condenser, preferably at or near the exhaust steam inlet, for maintaining uniform heating conditions at the given point under varying load conditions of the condenser with a uniform or full capacity flow of cooling water through the condenser.

More specifically, the present invention comprises a surface condenser for steam which has a feedwater heater located in the condenser shell in the path of the incoming steam and preferably,

16' near the steam inlet of the condenser, so that the incoming steam will be utilized to heat feed water' for a boiler prior to the condensation of the steam in the condenser.

In some instances and under certain condi- 20 tions the condenser will operate under partial load, as for example when the power unit in which the condenser is embodied is utilized as a stand-by unit. At such times the quantity of exhaust steam delivered to the condenser is greatly below the normal delivery and capacity of the condenser, but the cooling water fiowingthrough the tubes of the condenser is substantially normal. Such conditions result in a high degree of vacuum in the condenser, causing ineffective or reduced heating of the boiler feed water flowing through the heater. It is an object of the present invention to provide a method and means to compensate for such conditions and maintain uniform heating of the feed water under all conditions.

Another object of the invention is'to provide means automatically operated by the temperature of the feed water discharged from the heater to control the admission of air into the condenser to 40 lower the degree of vacuum therein and increase the absolute pressure at the exhaust steam inlet of the condenser in proportion to the decrease of the quantity of steam entering the condenser and therefore maintain uniform heating of the feed water in the heater or substantially uniform heating conditions in the predetermined or given part of a condenser.

Another object of the present invention is to provide in a condenser assembly as above referred to a thermal control valve structure operable under varying temperatures within predetermined degrees either in the outgoing feed water or in the condenser in the vicinity of the feed water for controlling the admission of air into the condenser.

Specifically, the primary object of the present invention is to control the absolute pressure in the condenser surrounding the feedwater heater by regulating the vacuum in the condenser through the delivery of'air into the condenser and con- 5 trollingthe delivery of such air automatically, either by temperature variances in the heated feed water or by variances in the absolute pressure in the portion of the condenser surrounding the feedwater heater. 10

By admitting air into the condenser, preferably in such manner as to blanket part of the water circulating tubes of the condenser, a rapid change in the absolute pressure within the condenser surrounding the feed water heating tubes 15 may be provided.

With these and other objects in view, as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts, which will 20 be first described in connection with the accompanying drawings, showing a surface condenser embodying the invention, and the features forming the invention will be specifically pointed out in the claims. 25

In the drawings: I

Figure 1 is a side elevation of a surface condenser constructed in accordance with this invention, having parts broken away to show the feedwater heater and utilizing the temperature 30 control for controlling the admission of air to the condenser.

Figure 2 is an end view of the condenser shown in Figure 1.

Figure 3 is a vertical cross-section through the 35 condenser, taken on the line 3-3 of Figure 1.

Figure 4 is an enlarged detail, partly in section, of the control valve and air admission structure.

Figure 5 is a vertical cross-section through a modified form of the condenser, also showing a 4 temperature or thermal control for the admission of air.

Figure 6. is a vertical cross-section through a modified form of the condenser showing pressure actuated control of the admission of air into 45 the condenser.

Figure '7 is a detail view, enlarged, and partly in section, of the pressure operated mechanism for controlling the admission of air into the condenser.

Referring more particularly to the drawings, and with special reference to the construction of condenser shown in Figures 1 to 4 inclusive, the condenser shell I is of any usual approved construction, having an exhaust steam inlet 2 through which exhaust steam from a turbine (not shown) passes into the interior .of the shell I where it is condensed during its passage through the tube bank 3 of the condenser. The condensate passes into the hot well 4, while the air is drawn off from the condenser through approved types of air outlets 5. In Figure 3 of the drawings 1 the condenser is shown as having what is commercially known as a folded tube bank arrangement of tubes, but it is to be understood that the arrangement of the tubes within the condenser shell I forms no part of the present invention and any approved or conventional arrangement of the tubes may be provided without departing from the spirit of the invention.

The present invention comprehends utilizing some of the heat of the incoming exhaust steam to heat feed water for a boiler (not shown) or for other purposes, and consequently a feedwater heater ID of the tube type is placed within the condenser shell l adjacent to the exhaust steam inlet 2, so that the incoming exhauststeam will first pass about the tubes ll of the feedwater heater for heating the feed water which is circulated through the tubes. From the feed water heater It the exhaust steam passes into the main body of the condenser, where it is condensed durduring its passage over the tubes 3' of the condenser proper,

The feedwater heater ll] comprises a plurality of passes, the construction showing being of a four pass type, comprising suitable water boxes l2, I3 and M. The feed water to be heated enters through the inlet l5, passes through the first set of tubes l6, returns through the second set I! to the water box l2, passes from the water box l2 through the connection l2 into the water box M, from whence it passes in forward and return passes through the sets l9 and 23 of the tubes of the feed water heater, finally being discharged from the feed water heater through the discharge 2i.

At times, such as when the power plant is operating at only partial load, or the particular unit in which the condenser is embodied is acting as a stand-by unit and idling, the quantity of exhaust steam delivered to the condenser is greatly below normal, and the capacity of the condenser. However, since it is necessary to have all of the parts of the power unit in readiness for almost instant throwing into the line, and since there is some exhaust steam being delivered to the condenser, it is necessary to circulate cooling water through the tubes 3 of the condenser in suflicient quantity to provide sufiicient condensing fiow therethrough, and to chill all of the tubes so that the flow of the cooling water through the tubes of the condenser is substantially normal. This substantially normal flow of cooling waterthrough the tubes with a greatly reduced quantity of exhaust steam being delivered to the condenser causes an increased or higher vacuum in the condenser than under normal operations. The higher or increased vacuum in the condenser causes the reduced quantity of exhaust steam to be drawn rapidly into the tube banks of the condenser and quickly condensed, resultingin reduced heating of the feed water passing through the feedwater heater. For practical, economical reasons it is desirable and necessary to provide a substantially uniform temperature of the feed water leaving the feedwater heater, therefore the present invention comprehends the provision of means to provide the desired uniform heating of the feed water irrespective of the quantity of exhaust steam which is delivered to the condenser This result is accomplished by reducing the vacuum in the condenser and consequently raising the absolute pressure in the condenser shell and particularly at the portion of the interior of the shell above the tube banks and surrounding the feedwater heater ID.

The vacuum in the condenser is reduced and the absolute pressure about the feedwater heater raised by the admission of air into the condenser shell. In Figures 3 and 6 the air passes into the condenser shell through an admission pipe 30, from which it is delivered by a suitable branch 3| to

pipes

32 and 33. The

pipes

32 and 33 extend longitudinally of the condenser directly above the uppermost portions of the tube banks 3, and the

pipes

32 and 33 are perforated so that air entering the

pipes

32 and 33 will pass out of these pipes in small streams or jets over the top of the tube banks, and substantially blanket the tube banks with air, resulting in the lowering of the vacuum in the condenser shell and in retarding the passage of steam into and through the tube banks, consequently increasing or building up the absolute pressure in the condenser above the tube banks and retarding the velocity of flow of exhaust steam through the feedwater heater ill.

Owing to the fact that the flow of exhaust steam will be irregular, means have been provided for automatically regulating the flow of air into the condenser, The forms of the invention shown in Figures 1 to 5 inclusive show thermal means for controlling the flow of air into the condenser, while the forms shown in Figures 6 and 7 show pressure operating means for controlling the flow of air into the condenser.

Referringfirst to the thermal means employed, a thermal bulb 36 is inserted in the outlet 2! of the feedwater heater and is acted upon by the temperature of the feedwater heater. This thermal bulb 36 is connected to a valve actuating mechanism 31, which mechanism is responsive to temperature changes for opening and closing the valve structure 38. This thermal unit, comprising the bulb 36, mechanism 31, and valve 38, may be of any approved type which can be purchased upon the open market, such as those manufactured by the Taylor Instrument Company, the Fulton Company, or others.

The mechanism 31 may be set to operate between any predetermined degrees of temperature, so that when the temperature of the feed water in the discharge of the feedwater heater drops below a predetermined degree, the mechanism 3! will act to open the valve 38, and admit air into the'air admission pipe 30 for delivery into the condenser. The degree of opening of the valve 38 and consequently the quantity of air admitted to the condenser will be regulated by the temperature variances of the feedwater in the discharge of the feedwater heater, or the point at which the bulb 36 is located. As the temperature of the feed water rises, the mechanism 31 will act to retard the delivery of air into the condenser, cutting off the delivery of air entirely when the maximum temperature degree desired is reached by the feed water,

An air strainer 39 is provided for straining the air prior to its entering into the condenser, and a, manually operated valve 40 is also provided between the automatically operated valve 38 and the interior of the condenser to permit manual closing of the air admission pipe 30 if desired.

In the modified form of the construction shown .in Figure 5 of the drawings, the condenser structill ture l' and the feedwater heater structure III are Just the same as in the preferred form shown in Figurfs 1 to 3 of the drawings, and a thermal device 4 which is the same as the thermal device employed in the preferred construction of the invention shown, is provided and operated by the temperature of the feed water 'at the discharge of' the feedwater heater. However, in this modified form the air admitting structure is slightly different.

In the construction shown in Figure 5 of the drawings a by-pass 42 is connected to the air admission pipe 43 between the manually operated valve 44 and the automatically operated valve 45. The by-pass 42 connects to the air outlet pipe 46, which conducts the air from the air outlets 41 of the condenser to the ejector or other suitable air pump structure 48. Therefore when the manually operated valve 44 is open, and the automatically operated valve 45 is also open, a part of the air passing through the automatically operated valve 45 will be by-passed through the by-pass 42 directly to the air pump 48 with a part of the air passing into and through the air admission pipe 43. A manually operated valve 49 is provided in the by-pass 42 for closing this bypass so that all or the air passing through the valve 45 will pass through the air admission pipe 43 into the condenser, or if the valve 49 is opened and the valve 44 closed, then all of the air will pass directly through the by-pass 42 to the air pump 48.

In this modified construction the a'irpasses from the air admission pipe 43 through suitable connections 50 to a plurality of pipes 5i. The pipes 5| are-located within the tube banks 3' of the condenser structure, so that the air will be admitted directly into the tube banks in lieu of being delivered to the condenser exteriorally of the tube banks, as shown in Figure 3-.

If it is desired, a reservoir 52 may be provided in the air admission pipe 43 to overcome or compensate for fluctuation in the flow of air through the valve 45.

In Figures 6 and 'l a further modified form of the invention is shown, and as hereinbefore stated, the condenser structure i together with the air admission'pipe 30 and

air outlet pipes

32 and 33, are the same as in the preferred form shown in Figures 1 to 3 inclusive. This modified form shown in Figures 6 and '7 differs from the preferred form in that the automatically operated valve is operated by pressure variances rather than by thermal variances.

The valve structure 60 is connected toa mechanism 6| of the pressure operating diaphragm type, such as may be purchased upon the open market. The mechanism 6| includes the diaphragm 62, enclosed in a suitable housing 63, with the space 64 below the diaphragm open to atmosphere through the vent 65. The space in the housing 63 above the diaphragm 64 has a pipe 66 connected thereto which extends into the condenser shell I and opens out therein, in the vicinity of the feedwater heater 61. The feedwater heater 51 is of the same construction as the feedwater heater I0 and Hi. When the absolute pressure in the condenser shell about the feedwater heater 61 falls below a predetermined point, the pressure against the diaphragm 62 from the condenser will .be relieved and the diaphragm will move to open the valve structure 60 to admit air to the condenser. When the absolute pressure in the condenser rises to the maximum degree setting of the mechanism 6|, the

diaphragm will operate to close the valve 54, while intermediate pressure between the maximum and minimum setting of the member 6| will act to control the quantity of air delivered into the condenser, through the throttling action of the valve 60.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown, but that they may be widely modified within the invention defined by the claims.

What is claimed is: v

1. The method of maintaining a substantially fixed temperature at a predetermined point in a surface condenser for steam under varying conditions of load which consists in introducing air into the suriace condenser to reduce the vacuum therein, and controlling the introduction of such air by temperature at the point where the fixed temperature is to be maintained.

2. The method of maintaining a substantially fixed temperature at a predetermined point in a surface condenser for steam under varying conditions of load which consists in introducing air into the surface condenser to reduce the vacuum therein, controlling the introduction of such air by temperature at the point where the fixed temperature is to be maintained, and regulating the quantity of air introduced into the condenser proportionally to the degrees of temperature variances at said point of control.

3. The method of regulating the absolute pressure at a predetermined place within a surface condenser to' maintain predetermined heating conditions ther eat under wide variances in the quantity 'of steam delivered to .the condenser, which consists in introducing air into the condenser to reduce the vacuum therein.

4. The method of regulating the absolute pres sure at the exhaust steam inlet of a surface condenser to maintain predetermined heating conditions near the exhaust steam inlet under wide variances in the quantity of steam delivered to the condenser, which consists in introducing air into the condenser to reduce the vacuum therein, retard the flow of exhaust steam through the condenser and build up the absolute pressure at the exhaust steam inlet in inverse proportion to the reduction in the quantity of exhaust steam delivered to the condenser. v

5, The method of regulating the absolute pressure at the exhaust steam inlet of a surface condenser to maintain predetermined heating conditions near the exhaust steam inlet under wide variances in the quantity of steam delivered to the condenser, which consists in introducing air into the condenser to reduce the vacuum therein, retard the flow of exhaust steam through the condenser and build up the absolute pressure at the exhaust steam inlet in inverse proportion to the reduction in the quantity of exhaust steam delivered to the condenser, and controlling the admission of air into the condenser by the variances of the absolute pressure at the exhaust steam inlet.

6. Thecombination with a surface condenser, having a-shell provided with a steam space and cooling water conducting tubes therein, and a feedwater heater in said steam space, of means for admitting air into said condenser shell, said means acted upon by the absolute pressure in the shell surrounding the feedwater heater for maintaining the absolute pressure in the shell about the feedwater heater within a predetermined range under varying quantities of steam delivered to the condenser.

7. The combination with a surface condenser, having a shell provided with a steam space and cooling water conducting tubes therein, and a feedwater heater in said steam space, of means for admitting air into the condenser shell to form a blanket of air about at least some of said tubes to raise the absolute pressure in the condenser shell around said feedwater heater, and means acted upon by the temperature of water discharged from said feedwater heater for regulating the quantity of air admitted into the shell.

8. The combination with a surface condenser, having a shell provided with a steam space and cooling water conductingjubes therein and a feedwater heater in said steam space, of means for admitting air into the condenser shell to form a blanket of air about at least some of said tubes to raise the absolute pressure in the condenser shell around said feedwater heater, a valve for controlling the admission of air into the condenser shell, and means acted upon by the temperature of feed water discharged from said feedwater heater for operating said valve.

9. The combination with a surface condenser, having a shell, an exhaust steam inlet, a bank of cooling water conducting tubes in the shell, and an air pump for removing air from the shell, of an air inlet pipe extending into the shell and having its inlet open to atmosphere, said pipe having a plurality of outlets arranged to discharge and distribute a blanket of air into said condenser for raising theabsolute pressure within the shell.

10. The combination with a surface condenser, having a shell, an exhaust steam inlet, a bank of cooling water conducting tubes in the shell, and an air pump for removing air from the shell, of an air inlet pipe extending into the shell and having its inlet open to atmosphere, said pipe having a plurality of outlets arranged to discharge and distribute a blanket of air into said condenser for raising the absolute pressure within the shell and pressure actuated means responsive to pressure conditions in a predetermined area in the condenser for controlling the delivery of air into the condenser through said air inlet pipe.

11. The combination with a surface condenser having a shell, an exhaust steam inlet, a bank of cooling water conducting tubes in the shell, and an air pump for withdrawing air from the shell, of a feed water heater in said shell for heating water by exhaust steam in the condenser, an air inlet pipe extending into said shell and having its inlet open to atmosphere, said pipe having a plurality of outlets arranged to discharge and distribute a blanket of air into the condenser for raising the absolute. pressure within the shell,

and means actuated by the temperature of feed water discharged by said feed water heater for controlling the delivery of air to the condenser through said air inlet pipe,

12. The combination with a surface condenser having a shell, an exhaust steam inlet, a bank of cooling water conducting tubes in the shell, and an air pump for withdrawing air from the shell, of a feed water heater in said shell for heating water by exhaust steam in the condenser, an air inlet pipe extending into said shell and having its inlet open to atmosphere, said pipe having a plurality of outlets arranged to discharge and distribute a blanket of air into the condenser for raising the absolute pressure within the shell, and means acted upon by the absolute pressure in the shell surrounding the feed water heater for controlling the delivery of air into the condenser through said air inlet pipe.

13. The combination with a surface condenser, having a shell, an exhaust steam inlet, a steam space within said shell, cooling water conducting tubes within the shell, an air pump for removing air from the shell, and a feed water heater in said steam space, of means for admitting air into the condenser shell to form a blanket of air about at least some of said tubes to raise the absolute pressure in the condenser shell around said feed water heater, and means acted upon by the absolute pressure in the shell surrounding the feed water heater for controlling the admission of air into the condenser shell.

14. The combination with a surface condenser, having a shell, an exhaust steam inlet, a bank of cooling water conducting tubes in said shell, and an air pump for removing air from the shell, of an air inlet pipe extending into said shell and having its inlet open to atmosphere, said pipe having its outlet arranged to discharge and distribute a blanket of air into said condenser for raising the absolute pressure within the shell, a valve for controlling inlet of air into the shell through said inlet pipe, and means for actuating said valve.

15. The combination with a surface condenser having a shell, an exhaust steam inlet, a bank of cooling water conducting tubes in said shell, said bank arranged to provide an inlet side for the entrance of steam into the tube bank, and an air pump for removing air from the shell, of an air inlet pipe extending into said shell and having its inlet open to atmosphere, said pipe having its outlet arranged to discharge and distribute a blanket of air into the condenser between the steam inlet portion of the tube bank and said exhaust inlet, and means for controlling the admission of air into the condenser through said pipe.

JOHN F. GRACE.