US1766678A - Fluid-pressure apparatus - Google Patents

Description

June 24, 1930. w. G. NoACK FLUID PRESSURE APPARATUS Filed April 20, 1927 2 Sheets-Sheetv 1 June 24, 1930. w. G. NoAcK 1,766,678

FLUID PRESSURE APPARATUS Filed April 20, 1927 2 Sheets-Sheet 2 Patented June 24, 1930 UNI-TED STATES PATENT OFFICE WALTER GUSTAV NOACK, 0F BADEN, SWITZERLAND, ASSIGNOR TO AKTIENGESELL- SCHAFT BROWN BOVERI & CIE., OF BADEN, SWITZERLAND, A JOINT-STOCK'COM- IPANY, 0F SWITZERLAND FLUID-PRESSURE APPARATUS Appneatinn'med April 2o, 1927, serial No. 185,140, and in Germany Api-i1 26, i926.

rIhis invention relates to operation of steam power plants, and pertains more particularly to control of steam turbines of the extraction type wherein steam is extracted for the purpose of feed water heating or similar uses for which the requirements are variable.

The general object of the invention is the provision of an improved method of operation, with respect to control of steam supply to the extraction machine, and an improved apparatus whereby the method may be practiced automatically to effect economical and eflicient operation of the installation.

Another object is the provision of a method and apparatus for controlling supply of steam to an extraction turbine, or the like, in accordance with demand for extracted steam.

Another object is the provision of a method for controlling extraction of steam from a turbine for feed water heating, through control of the steam supply to the turbine through the medium of the feed Water.

Another object is the provision of apparatus whereby the amount of steam extracted from a turbine for feed water heating may be controlled automatically by the water to be heated.

Other and further objects will be pointed out or indicated hereinafter or will appear to those skilled in the art upon an under- Y standing of the invention or its employment claims short of the true and most comprehensive scope of the invention in the art.

In said drawings, c Fig. 1 isa schematic illustration of power plant apparatus including an auxiliary turbine of the extraction type, together with,

feed water heating apparatus and automatic control mechanism for governing the steam supply to the turbine in accordance with the quantity of feed water supplied for preheating, portions of the automatic control mechanism being shown in sectional elevaif tion; and v Fig. 2 is a diagrammatic illustration of automatic control mechanism of the type illustrated in Fig. l, shown for the most to part in sectional elevation. It is old in the artv toV preheat the boiler water for a steam power plant by means of steam extractedfrom the turbine or engine. For obtaining satisfactory operation, care5 tain advantages are attained by extracting this heating steam from an auxiliary turbine, rather than from a mainturbine of the plant. By having this auxiliary turbine of the back pressure extraction type, with variable extraction pressure and back pressure,A` it would be possible to maintain a constant feed water temperature in spite of load variations. Such an arrangement would possess a disadvantage in the fact that when the demand for boiler feed is small, the load on the turbine would be reduced to zero, since, in the absence of a condenser, the steam supply to the turbine would be stopped. Moreover, substantial losses would1 so be entailed by the frequent adjustment of the*-A quantitytaken off at the extraction points to meet variations in the feed water demand. In the event the extraction turbine were provided with a condenser, heat losses would be entailed in the condenser cooling water.

YBy doing away with regulation of the excertain disadvantages and poor economy as re ards both first cost and running cost.

y the present invention, there are provided a method of operation and apparatus whereby it may be practiced automatically, through which these various disadvantages are avoided or overcome, the same involving the regulation of the supply of steam to the extraction turbine, as by throttle or nozzle control at the inlet, and the extraction varied according to variation of the suppl This control may be accomplished accurate y and in accordance with the momentary condition of the power plant by utilizing the feed water as a factor for controllingV the steam su ply to the extraction turbine. The nature of the invention may be ascertained in more detail by consideration of the illustrative installation shown in the drawings. Here the reference numeral designates a steam boiler for supplying the power plant, which includes a main turbine or engine, and an auxiliary turbine 11 adapted to operate auxiliar apparatus, such as the generator 12. The auxiliary turbine 11 is supplied with steam from boiler 10 by way of the line 14 and through an inlet control valve 15 adapted to be opened and closed by valveo yrating mechanlsm 16. The auxiliary turb1ne has the tapping points 17, 18 and 19 from which steam is extracted to supply the feed water heaters 20, 21 and 22 respectively, the feed water being taken from a reservoir 24 supplied by a pipe 23 from the. condenser of the main turbine. The line 26 containing the pump 27 returns condensate from the heaters 20, 21 and 22 to the reservoir 24. The feed water to be heated is drawn from reservoir 24 by pipe 25 and fed to the preheaters through a flow-metering device 28, the latter constitutin a detecting device for a regulator 29 whici infiuences the operation of the valve-operating mechanism 16.

The valve-operating mechanism, as illustrated in more detail in Fig. 2, is of a known t pe in which the pressure of oil in a servo line 30, supplied from a pump 31, is effective upon a piston 16, against the loading of a spring 16b to control the position of the inlet valve 15. The pressure of the oil in the servo line 30 is under control of the regulating device 29, which includes an adjustable sleeve 29a containing an aperture 29", the effective area of which may be varied by varying the position of the sleeve, to vary the escape of oil from the line 30. As the effective area of the orifice 29" is decreased, the pressure in line 30 will increase, with the result that the piston 16 will be raised and the throttle valve 15 opened, the reverse operations taking place when the sleeve 29 is positioned to increase the effective area of the orifice 29". The adjustable sleeve 29a is connected to a diaphragm 29c which is loaded in one direction by a spring 29d, which diaphragm is subjected on opv posite sides to di erential pressures obtained from the metering device 28 throu h the pipes 32 and 34. The device 28 may e of the so-called Venturi t ,as indicated in the drawing. By virtue o the arrangement, as the flow of feed water to the heaters through device 28 decreases, resulting in a decrease of the pressure differential between pipes 32 and 34, the spring 29d will move the sleeve 29n to increase the pressure oil leakage, with the result that the throttle valve 15 will be given a closing movement, throttling steam admission to the auxiliary turbine and resulting in the extraction of less steam for heating feed water. Vith au increasing of the flow of feed water through the flow-meter, the pressure differential between pipes 32 and 34 will be increased, with the result that the diaphragm 29e will be moved by the superior pressure to decrease the effective area of the orifice 29", decreasing escape of oil from the servo line and resulting in an opening movement of the valve 15. This has the effect of increasing the steam supply to the extraction turbine, thereby increasing the amount of steam extracted in an amount pro ortionate to the increase in the quantity of eed water being supplied for preheating. The oil discharged t rough sleeve 29* goes to a reservoir 35 from which it is pum ed into the servo line by the um) 31. e turbine may be supplied with t e customary speed governor system includin the overnor 36,

ut the valve 15 may be in epen ent thereof, the speed governor system bei so arranged as to come into operation on y when the speed of the turbine exceeds a maximum value fixed in accordance with the requirements of the auxiliary apparatus 12, or at such times as the feed heatin system may be out of action. The speed o the auxiliary turbine may be maintained constant by paralleling its generator with the main electrical system. In order to keep the turbine running when the demand for boiler feed is very low, a separately cooled condenser 37 may be provided, the condensate from the same being delivered to tank 24 through pipe 38.

The operation of the apparatus having been described in connection with the foregoin detailed description of the mechanism, 1t wi l be apparent that the method of steam plant control performed, as by the means above described, includes the extraction of heating steam from the auxiliary turbine in accordance with the requirements therefor as established by the quantit of feed water to be heated, said extraction being controlled by regulation of the steam su plied to the turbine effected through tiie medium of the feed Water supplied for heating.

What I claim is:

In apparatus of the character described, a steam-operated prime mover, valve means operable to provide for the supply of operating steam to said prime mover, governing means for said Valve means, a uidconduit, steam-operated heating means associated with said conduit and operable to impart heat thereto, means providing for the passage of exhaust steam from said prime mover to said heating means, and means responsive to the relation between the respective Huid-pressures at diierent points in said conduit and operable upon variation in such relation to efect governing action of said governing means.

In testimony whereof I have hereunto subscribed my name this 1 day of April, A. D. 1927, at Zurich, Switzerland.

IVALTER GUSTAV NOACK.

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