US1584915A - Elastic-fluid turbine - Google Patents

Description

May 18 1926.

0. D. H. BENTLEY ELASTIC FLUID TURBINE Filed August 18, 192" V w n\ w 1| i N:

\\\I :1 a l I May 18 ,1926.

I o. D. H. BENTLEY ELASTIC FLUID TURBINE Filed August 18, 1923 2 Shets-Sheet 2 Patented May 18, 1926.

UNITED STATES PATENT OFFI OLIVER D. H. BENTLEY, or NORFOLK, MA vA T COMPANY, or HYDE PARK, MA

CHUSETTS.

SSACHUSETTS, AsSIGNOR To is. r. sTURTE ssAcHUsETTs, A CORPORATION or MASSA- ELASTIC-FLUID TURBINE.

Application filed August 18, 19t 23. Serial No. 658,131.

The present invention relates to elastic fluid turbines and more especially to turbines designed for idling at low speeds.

In certain industries it is desirable to provide elastic fluid turbines which will idle economically at speeds considerably lower than the normal running speed. This is particularly true in gas producer work where turbo blower is used to force a draft of air through the generator.

for a short period of time in order to force the air through the generator, after which the blower is shut down to allow production of the gas in the usual manner. When the blower is not being run at full speed it is desirable to have it idling at a relatively low speed, not only in order to maintain a sutficient pressure to prevent dangerous leakageof the combustible gases back into the blower system, but also to keep the turbine thoroughly heated and in proper condition for immediate operation at full speed and eliieiency. The usual practice for causing the turbo blower to idle at low speeds consists merely in throttling the turbine steam supply down to a low pressure. For example, for a turbine running at full load under a pressure of one hundred and fifty pounds the steam would be throttled down to approximately fifteen pounds in order to permit the blower to idle at approximately ten to fifteen per cent of normal full load speed. The design of the turbine nozzles is such, however, that idling-at such low pressures is extremely ineflicient. Accordingly, it has been the practice to compromisebetween the high and low pressures and to provide nozzles designed for an intermediate pressure, say one hundred and twenty-live pounds. This improves the idling efficiency slightly, but only at the expense of the running efliciency, since a nozzle will not operate at a pressure higher than,that for which it is designed without excessive losses due to eddying.

The object of the present invention is to provide a turbine'which has provision for idling at low speeds and which will run economically and at high eliiciency at both highand low speeds. To this end the invention consists in the turbine hereinafter described and particularly defined in the claims.

The blower runs. only intermittently, being kept at full speed;

Th preferred embodiment of the present invention contemplates the provision of a turbine having a plurality of nozzles all properly designed for operation undern'ormal steam pressures, together with means for supplying the steam or other working fluid turbine under normal running conditions, and means forsupplying the working fluid at normal steam pressure to onlya portion of the nozzles for the purpose of idling at a lower speed. Thus during full speed operation all of the nozzles arefed with the working fluid at substantially the high pres sure of the supply and expand the fluid t0 the pressure determined by the conditions within the turbine casing, whereas during idling the fluid is expanded only through the idler nozzle or nozzles but still between the same pressures. being designed for the same degree of expansion, will operate with full efliciency, both at full load and also at idling speeds. In the accompanying mg the preferred form of the invention Fig. 1 is an elevation, partly in section, of the improved turbine; Fig. 2 is an end elevation of the turbine; Fig. 3 is an enlarged section on line 33 of Fig. 1; and Fig. 4 is an elevation of a power unit employing the improved tnrbine in connection with a fan or blower.

The invention is herein illustrated and described as embodied in a turbine adapted to run a blower for gas producer work. The complete assembly is illustrated in Fig. 4 which shows a turbo blower comprising a turbine 6 and a blower 8 connected through the shaft 10, which is journaled in end bearings 12 and 14. The turbine comprises a rotor or bucket wheel l6 mounted upon the shaft 10 and provided with a series of peripheral buckets 18 of the usual form. The rotor is enclosed by a turbine casing 20 having suitable exhaust port 22.

A series of regularly disposed nozzle segments are mounted in a manner to direct the steam to the bucket wheel. The illustrated embodiment of the invention employs eight nozzle segments, of which seven (indicated at 24) are secured to an incomplete annularstealn chest 26, which in turn is secured to the turbine casing. The eighth nozzle segment, 27, which may be termed the to all of the nozzles for operating the.

drawings illustrat.

Each nozzle, therefore,

idler segment, is secured to a separate steam chest 28 which is also secured to the turbine casing. The nozzle segments are of any usual or preferred form having a flange 30 for bolting to thesteam chest,'a nozzle opening having the proper expansion ratio for the predetermined steam pressures and a plurality of reversing buckets 34.

The nozzles 24, which for convenience may be referred to as the power nozzles, are provided with throats or passages of large capacity so as to admit steam to almost the full capacity of the bucket wheel. Each nozzle is provided with the usual hand actuated valve 36 by which the passage of steam from the steam chest to the nozzle may be controlled. The steam is supplied to the chest 26 from any convenient source through a pipe line 38 which is connected to the steam chest by a coupling 40. The supply of steam to the chest is controlled by a governor valve 42 and a quick acting valve all. The governor valve is actuated upon changes of speed through a governor 46 of the general type described in the Bentley Patent No. 1,103,024, mounted at the end of the turbine shaft. The quick acting valve ll is operated so as to cut the steam suddenly off from the steam chest and is preferably actuated through a remote control indicated generally at lS from the gas producer.

The idler nozzle 27 is provided with a throat or passage smaller than those of the power nozzles, but having the same expansion ratio. The size of the idler nozzle is such that just enough steam'will be delivered at the normal steam pressure to drive the turbine and blower at the predetermined idling speed. The idler steam chest 28 is fed from the pipe line 38 through a pipe 50 which is coupled to the pipe line at52 and to the steam ,chest at and which by-passes both of the controlling valves 42 and set so that the latter have no effect upon the admission of steam to the idler nozzle.

Under running conditions steam is supplied to all of the nozzles at the original high pressure of the source, except for such slight variations as occur through the action of the governor valve. After the producer has run from three to live minutes the quick acting valve ell closed, thereby permitting the passage of steam only to the idler nozzle. Since the load upon the blower increases rapidly with the speed, it will be apparent that the greatly reduced amount of steam now presented to the turbine will be effectual only to rotate the unit at a considerably reduced speed. In practice it; is desirable to have. the turbo blower idle at approximately li'l'teen per cent. of lfull load speed, this being fast enough to build up sutlicient pressure to prevent any dan erous back leakage of the combustible ga the producer. The steam Ct)ll:'l1l1)].)tl0i1 necessary/to rotate at this speed is only about; three 'or four per cent of normal steam consumption.

During the normal full load operation of the turbine, the seven nozzles 32 furnish the greater part of the power to the rotor. The idling nozzle, however, contriln-i'tes to the operation at such time delivering its smaller amount of steam at the same high elliciency as the power nozzles and without unbalancing the turbine or otherwise detracting from the economy of its performance. \Yhcn the valve ff is closed the turbine idles by the steam supplied through the idling nozzle 33 with the same high clliciency. It has been found that this idling nozzle takes onlv about one-quarter of the amount of steam required where the steam is simultaneously throttled at all the nozzles. Since all the nozzles are designed properly for the pressures with which they are to be used, the turbine also runs with maximum ellicicncy at the high speeds and-full power, as distinguished from the inellicient performance of variable pressure turbines which employ over-eipanded nozzles as a compromise between the running and idling pressures.

While in the foregoing specification and drawings there has been described and illusstratcd what is now considered to be the preferred embodiment of the present invention, wherein the elastic lluid is supplied to all of the nozzles, both the power and the idling nozzles, at the same pressure, it to be understood that the present invention is not necessarily limited to such a construction and arrangement but may, except where so specifically limited in the claims, be embodied in other constructions and arrangements.

Having thus described the invention what is claimed is:

1. A turbine having, in combination, a rotor, a nozzle of large capacity. a nozzle of small capacity, both nozzles havingthe same expansion ratio. means for supplying work ing fluid to the larger capacity nozzle, controlling means for the iltlltl supply; and means for supplying working lluid to the smaller capacity nozzle at the same pressure but independently of the said controlling means.

2. A turbine having, in combination, a rotor, a plurality of power nozzles, means including a single cut oil valve for supplying working fluid to said nozzles, an idlin;- nozzle of less capacity than the power nozzles, and means for supplying working lluid to the idling nozzle when the lluid cut oil' from the power nozzles.

3.1K turbine having. in comoination. a rotor, a power and an idling nozzl a governed steam supply for the power 12oz l1. an ungovcrned strain supplv at the ac pressure for .the idling nozzle, and ln llns of nozzles and the other for the remainder,-

and speed controlled means for cutting oil the source of supply from the first mentioned set of nozzles, whereby the turbine Will operate normally with all the nozzles in action and will idle with the first mentioned set of nozzles out of action.

A power unit having, in combination I a rotary blower, a turbine having power and idling nozzles, a steam supply for the nozzles, a common connection from the steam supply to the power nozzles, a valve in the connection, a direct connection from the steam supply to an idling nozzle and bypassing the said valve, whereby the steam may be supplied to all the nozzles for running the blower under load at normal speed and only to an idling nozzle when the valve is closed forv driving the blower at low speed.

6. A turbine having, in combination, a rotor, a plurality of nozzles, a common steam chest for the majority of the nozzles, and a sepalf i e Steam chest for the remainder, and means for controlling the supply of steam to the common steam chest only.

71-h turbine having, in combination, a rotor, a plurality of nozzles, a common steam chest for all but one of the nozzles, a steam supply line for the common steam chest, a valve in the supply line, and a connection from the supply line to the remaining nozzle and bypassing the valve in a manner to allow idling ot the turbine through the single nozzle when the valve is closed.

8. A turbine having, in combination, a

- plurality of nozzles, one of the nozzles being smaller than the remain ng nozzles, a

steam chest for the smaller nozzle, and a common steam chest for the remaining nozzles.

9fA turbine having, in combination, a rotor, a plurality of nozzles, a steam line, a main connection-from the steam line to the majority of the nozzles, means for cutting off the steam in the main connection, and a connection from the steam line to the remainder of the nozzles and by-passing the cut-off means so that steam may be supplied only through the second connection for idling.

10. A turbine having, in combination, a rotor, a series of nozzles including a plu- 'rality of power nozzles and an idling nozzle of smaller size, means for supplying steam to all the nozzles when the turbine is running under a load, and means for supplying steam only to the idling nozzle but at the same pressure for idling.

11 ..A- turbine having, in combination, a series of nozzles including a plurality of power nozzles and an idling nozzle of different size from the power nozzle, all ofthe nozzles being designed for expansion between the same-pressures, means for supplying steam to the power nozzles, a governor and a cut-off valve for controlling the flow of steam to the power nozzles, and a separate steam connection to the idling nozzle which by-passes the governor and the cutoff valve, whereby steam may be supplied only to the idling nozzle, but at normal pres sure when the cut-off valve is closed.

12. A turbine having, in'combination, a rotor, a power nozzle, an idling nozzle, means for supplying elastic fluid to the power nozzle at the proper pressure for the expansion ratio of the nozzle, devices for cutting ofi the supply of elastic fluid to the power nozzle to permit the'turbine to idle and connections for supplying elastic fluid to the idling nozzle at the proper pressure for the expansion ratio of said nozzlev when the supply to the power nozzle is cut off.

OLIVER D. H. BENTLEY.

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