US1760471A - Power plant - Google Patents

Description

B. BROIDO POWER PLANT May 27, 1 930.

Filed NOV. 24, 1926 2 Sheets-Sheet 1 A TTORNE Y.

.BEI/VJAM/A/ .BPO/DO. I N V EN B. B ROIDQ POWER PLANT May 27, 1930.

Filed Nov. 24, 1926 2 Sheets-Sheet 2 fiEA/QAM/A/ zEO/ o. INVENTOR.

A TTORNE Y.

Patented May 27, 1930 UNITED STATES PATENT OFFICE BENJAMIN BROIDO, on NEW YORK, N. Y., ASSIGNOR '20 THE SUPERHEATER COMPANY,

on NEW YORK,. N. Y.

POWER PLAN T Application filed November 24, 1926. Serial No. 150,478.

My invention relates to power plants and has for its general object the improvement in the efliciency and operating economy thereof..

.In commercial power plants where steam is utilized in compound prime movers, it is a common practice to reheat the exhaust steam leaving the high pressure stage before it is utilized in the low pressure stage. Various methods have been proposed for reheating this exhaust steam, the most common means being either by returning the steam from a point between stages to reheaters located in the boilers or by reheating the exhaust steam by means of live steam.

\Vith the present methods of reheating by means of live steam, the low pressureexhaust steam cannot be brought to a temperature materially higher than that of the saturation temperature of the live steam used as a heating "medium, even though the latter be superheated. and in order to overcome this difiiculty it has been suggested that the exhaust steam might be reheated by steam at a very high pressure generated in a special Boiler.

' Reheating of the exhaust steam is usually considered only in connection with large turbines, and the amount of steam required for reheating in such cases is considerable. The amount of heating steam required to raise the temperature of a given quantity of low pressure exhaust steam 100 deg. is usually from 5 to 6 per cent of the amount of steam heated,

' and, if as is desirable, the reheated steam is raised 300 deg. in temperature, over 15 per cent of the total amount of steam reheated is required for reheating. In the case of a large unitof 50,000 kilowatts or more, this would involve a comparatively large high pressure boiler to supply steam for reheating purposes and the cost of such an installation, in addition to the complication involved. would ordinarily make this arrangement, al-

though desirable from the standpoint of efficiency, economically impractical.

In accordance with my invention, the advantages of reheating by the use of live steam, that is to say. the elimination of the complications necessary for reheating in the boilers, are retained and the reheating of the exhaust steam is accomplished by the use of a comparatively small high pressure boiler which supplies heating steam only for the final stage of the reheating.

In the accompanying drawings I have shown in diagrammatic form illustrative embodiments of my invention, Fig. 1 representing a preferred form of construction, Fig. 2 representing a modification, and Fig. 3 being a cross section of a portion of Fig. 2 taken at right angles thereto.

Referring now to the form shown in Fig. l, the numeral 10 represents a conventional form of boiler which may be one of a battery comprising the main source of operating steam for the plant. The boiler is provided with the usual superheater 11 from which steam is delivered through the conduit 12 to the high pressure unit 13 of theplant, which in the present instance has been illustrated as a turbine. The high pressure unit exhausts through the conduit 1-1 into a reheater 15 and passes from the latter through the conduit- 16 to the low pressure unit 17 which has been shown as a second turbine exhausting into the condenser 18. 'hile I have shown the power plant as comprising two separate turbines. itis apparent that the plant may consist of a multiple cylinder turbine or even a compound reciprocating unit. heating elements 19 and :20 which I have illustrated diagrammatically as tubular coils but which may be of any desired form. Theheating element 19 is supplied with live steam from the main boiler 10 through conduit 21 and the steam supplied thereto is preferably entirely condensed in the coil, the

The reheater 15 is provided with two condensate passing'throua'h the. conduit 22 to the hot-well 23. It is to be noted in this connection that the heating element 19 is placed at the end of the reheater where the exhaust steam enters.

The heating element 20, placed adjacent the outlet end of the reheater, is supplied through conduit 24 with live steam from a boiler 25 which generates steam at a pressure materially higher than the pressure existing in the main boiler '10.

The steam supplied through the conduit 24 is preferably entirely condensed within the heating element 20 and the condensate therefrom is returned directly to the boiler 25.

Because of the fact that the load on the boiler 25 is comparatively constant in character, this boiler may advantageously be of the continuous coil or flash type, to which the condensate from the heating element 20 is returned directly through the conduit 26.

In operation, the live steam supplied to the heating element 19 from the main boiler will serve to initially heat the exhaust steam to a temperature substantially that of the saturation temperature of the main steam supply. This temperature may be slightly exceeded because of the superheat in the steam con- .densed in the element 19, but in ordinary practice the saturation temperature will not be materially exceeded and for this reason it is not essential that the steam supplied to the filyater from the main boiler be superheated.

order to simplify piping arrangements, superheated steam may be supplied to the element 19, but saturated steam will serve equally well, as the major portion of the heating is accomplished by the latent heat of vaporization released by the condensation of the steam in the element 19.

After the exhaust steam has been initially heated by contact with the element 19, its temperature is further raised by contact with the element 20 which is supplied with steam generated at a pressure such that the saturation temperature is considerably above the temperature to which the exhaust steam has been. raised by the element 19. As the steam from the high pressure boiler 25 is preferably utilized wholly for heating purposes, it is not necessary to superheat this steam, as the advantage to be derived from superheating is not sufficient to warrant the expense of superheating equipment, and I therefore prefer to use-saturated steam in this element. It will be obvious, however, that, if desired, the steam generated in the high pressure boiler could be superheated before being utilized in the reheater.

Because of the comparatively small ran e through which the exhaust steam must Ee heated by the element 20, it is evident that the amount of steam required from the boiler 25 will be comparatively small. and the cost of this boiler may in consequence be materially reduced. The cost of the high pressure boiler is further reduced by the fact that a simple flash boiler may be utilized for the purpose, and b condensing all of the steam generated in t e reheater and returning it directly to the boiler the necessity of a boiler feed pump may be eliminated, as the necessary circulation may be obtained by thermal action.

In Figs. 2 and 3 I have shown a modified arrangement in which both the main boiler 10 and the auxiliary high pressure boiler 25 are installed in a common setting. In other respects, the arrangementof the several units in the plant is the same as that previously described, but in this arrangement I prefer to use an auxiliary high pressure boiler of the circulating type. For purposes of illustration I have shown the main boiler 10 as a conventional horizontal cross-drum type with the auxiliary boiler located at the top of the first and second passes of the main boiler. The auxiliary boiler is shown as of the same general type as the main boiler, with the steam generating tubes 27 located transversely of the main boiler tubes and delivering through suitable circulators to the steam drum 28 from which steam is led through the conduit 24' to the heating element 20. The condensate from the element 20 is returned through the conduit 26 to the water space of the boiler 25', and it will be evident that in this form of construction no pump will be required to .efi'ectcirculation through this system which forms, as does the one previ-' ously described, a closedcircuit all portions of which are under substantially the same pressure.

Obviously, the specific form of high pressure boiler incorporated in the setting of the main boiler is not an essential element of the invention, but I prefer to utilize a boiler of the circulating type in this form of construction because of the fact that fluctuations in the load on the main boiler will produce variations in the amount of heat supplied thereto which would adversely affect the operation of a flash type boiler.

While I have described my invention in connection with certain preferred embodiments thereof, it will be obvious that many changes in the arrangements and details of construction may be made b those skilled in the art., and my invention 1s. therefore, not to beconsidered as limited by the illustrative examples which I have chosen, but is to be considered as embracing all such changes and modifications as may fall within the scope of the appendedclaims. 4

I claim:

1. In'a steam power plant, the method of reheating steam exhausted from one consumer to a secondconsumer which consists in initially heating said steam with steam from the main steam supply and finally heating said steam with steam at a pressure higher than that of the main steam supply.

2. In a power plant, the method of heating steam exhausted from one consumer to a second consumer which consists in initially heat ing said steam with superheated live steam from the main steam supply and finally heating said steam with saturated steam at a pressure higher than that of said superheated steam supply.

The method of generating power which consists in generating steam supplies at different pressures, superheating the steam generated at the lower pressure, utilizing a portion of the superheated steam in aconsumer, initially heating the exhaust steam from said consumer with a portion of the superheated steam, finally heating the exhaust steam further with the steam generated at the higher pressure, and utilizing said finally heated exhaust steam in a low pressure consumer.

a. lln a power plant, a main steam supply, a high pressure consumer, a low pressure consumer operating on exhaust steam from said high pressure consumer, means for initially reheating the exhaust steam from said high pressure consumer with live steam from the. mam supply, and means for finally reheating said exhaust steam with steam at a pressure above that of the main steam supply.

5. ln a power plant, a high pressure cousumer, a low pressure consumer, a connection supplying exhaust steam from the high pressure consumer to the low pressure consumer, a reheater in said connection, a main steam generator supplying operating steam to said high pressure consumer and heating steam to said reheater, and an auxiliary steam generator supplying additional heating steam to said reheater. I

6. In a power plant, a high pressure consumer, a low pressure consumer, a connection supplying exhaust steam from the high pressure consumer to the low pressure consumer, a reheater in said connection, a main'steam generator supplying operating steam to said high pressure consumer and heating steam to said reheater, and an auxiliary steam generator supplying additional heating steam to said reheater at a pressure above that generated in said main generator.

7. In a power plant, a high pressure consumer, a low pressure consumer, a connection supplying exhaust steam from the high pressure consumer to the low pressure consumer, a reheater in said connection, a main superheated steam generator supplying superheated operating steam to said high pressure consumer and superheated live steam to said reheater, and an auxiliary steam generator supplying saturated steam to said reheater at a pressure higher than that of the superheated steam.

8. In a power plant, a main boiler, a superheater therein, a high pressure turbine, a low pressure turbine, a conduit supplying exhaust steam from the high pressure turbine to the low pressure turbine, a reheater in said conduit comprising a heating element adjacent the inlet end. of the reheater and a heating element adjacent the outlet end of the reheater, a conduit connecting said superheater with said first-named element, an auxiliary boiler operating at a pressure above that of the main boiler, and a conduit connecting said auxiliary boiler with said last-named element.

9. In a power plant, a main steam supply, an exhaust steam reheater comprising a heating element adjacent the inlet end of the re heater and a heating element adjacent the outlet end of the reheater, a conduit leading from the main steam supply to said firstnamed element, and a closed circuit system supplying steam to said last-named element at a pressure above that of the main steam supply.

10. In a power plant, a main steam supply, an exhaust steam reheater comprising a plurality of heating elements, a conduit leading from the main steam supply to one of said elements, and a closed circuit system supplying steam to another of said elements at a pressure above that of the main steam supply, said system comprising a continuous flow boiler, a conduit leading from the outlet end of said boiler to said element, and a conduit leading from said element to the inlet end of said boiler.

11. In a power plant, a high pressure consumer, a low pressure consumer, a connection supplying exhaust. steam from the high pressure consumer to the low pressure consumer, a reheater in said connection, a main steam generator supplying operating steam to said high pressure consumer and heating steam to said reheater, and a separately fired auxiliary steam generator supplying additional heating steam to said reheater at a pressure above that generated in said main generator.

12. The method of generating power which consists in generating steam supplies at different pressures, utilizing steam generated at a pressure below the highest pressure in a consumer, initially heating the exhaust steam from said consumer with other steam gener ated at a pressure below the highest pressure, finally heating the exhaust steam further with steam generated at a higher pressure, and utilizing said finally heated exhaust Steam in a low pressure consumer.

13. The method of generating power which consists in generating steam supplies at different pressures, utilizing steam generated at a pressure below the highest pressure in a consumer. initially heating the exhaust steam from said consumer with other steam at substantially the same pressure as that of the steam supplied to the consumer, finally heating the exhaust steam further with steam generated at the highest pressure, and utilizing said finally heated exhaust steam in a low pressure consumer.

14. The method of generating power which consists in generating steam at two diflerent pressures, utilizing steam generated at the lower pressure in a consumer, initially heating the exhaust steam from said consumer with steam generated at the lower pressure, finally heating the exhaust steam further with steam generated at the higher pressure, and utilizing said finally heated exhaust steam in a low pressure consumer.

BENJAMIN BROIDO.

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