US769300A - Turbine of the multiple-expansion type. - Google Patents

Description

No. 769,300. Q PATENTED SEPT. 6, 1904.

' 0. E BROWN. TURBINE OF THE MULTIPLE EXPANSION TY PE.

APPLICATION FILED AUG. 30. 1902.

N0 MODEL.

UNrr sn STATES Patented September 6, 190

Patent Genie-E.

TUR BINE OF THE MULTIPLE-EXPANSION TYPE.

SPECIFICATION forming part of Letters Patent No. 769,300, dated September 6, 1904. Application filed August 30, 1902., Serial No I2l,583. (No model.)

T at whom it warty concern:

have made application for Letters Patent in Great Britain, No. 15,432, dated July 10, 1902; in Switzerland, application filed February 4:, 1902, and in Germany, application filed February 7, 1902,)of which the following is a specification.

This invention relates to the regulating of steam and gas turbines of them ultiple-expansion type; the object of the invention being especially to improve the economy of such turbines when running at light loads.

The question of economy in turbines atlow speeds has already formed the subject of several patents by Parsons, such as the United States Patent No. 608,969, and others. It has also been arranged to pass steam to the second grade of expansion in a steam-turbine by hand valves. This invention, however, provides for accomplishing the same object automatically, so that economical and effective governing may be attained.

The'difficulties experienced hitherto in de signing a turbine of the above type which shall run economically at both full and'light loads arise from the followingfacts: If the areas of steam-passages are so proportioned as to give a maximum economy at full load, then at light loads the governor does not admit sufficient steam to fill these passages at full boiler-pressure, whereas if the areas are correctly proportioned to give a high economy at light loads then at heavier loads the small or high pressure end of the turbines has not sufficient area to pass the quantity of steam required to do the work. An improved economy would result if the area of blade-openings could be varied to correspond with the load, but this method is impracticable. The same result can, however, be attained in an other manner according to the present invention.

As is vvell known,multiple-expansion steamturbines are made with an increasing area from the high-pressure to the low-pressure end, and this is the case whether the turbine drives one shaft only-as,' for example, in a turbo-alternator or whether the turbine is split up into several portions, each driving a separate shaft, as in Parsonss well-known system of marine propulsion.

This invention consists in providing pipes or passages from the steam-chest to intermediate stages of the turbine, the openings to such passagesbeing automatically regulated from'a governor. Thus at quite light loads all these passages will be closed, and the small quantity of steam required passes direct through the small end of the'turbine, the area of which is suitably proportioned. As

the load increases one of thesteampassages will be opened, and additional steam will pass through it to a large part of the turbine. Finally, all the steam-passages will be opened, and enough steam will pass through to drive the turbine at full load. The number of steam-inlet passages may be chosen as large as desired. In many cases the use of one, two, or three such channels will give a favorable result in practice.

In marine installations where turbines forming part of the system work on different shafts regulation according to this invention may lead to a non-symmetrical distribution of the power between the different shafts. This, as a rule, is no practical disadvantage; but ifa symmetrical distribution at varying loads is required the difl'erent turbines may easily be arranged to give this result.

Referring to the accompanying drawings, Figure 1' shows this invention constructed according to one invention. Fig. 2 shows a second modification wherein the valve admitting steam to thepassages mentioned above is controlled direct from the governor. Fig. 3 is a diagram illustrating the improved economy resulting from this invention.

In Fig. 1, which represents' one modification of the invention, the turbine itself is shown at 1. and the main steam-inlet at 2 2. Pipes or channels 3 4L 5 lead to intermediate stages of the turbine, their inlets 6 preferably taking the form of annular openings controlled by a valve 7 This valve may be so arranged as to close the first port after opening the second, if desired. It is shown attached to a piston 10, controlled by a spring 11 and moving according to the pressure in the valve-chest, which is shown regulated by a governor 9, actuating a valve through the lever 8.

- the influence of the current generated.

In Fig. 3 the two curves A and B represent the steam consumption at various loads, the curve A corresponding to turbines as hitherto constructed and the curve B to turbines regulated according to the present invention. It will be noticed that while the consumption at heavy loads remains unaltered the consumption at the lighter loads is materially improved.

In all the above methods of actuating the valve-gear it is assumed that the governing of the turbine as a whole is effected in the usual mannerthat is to say, that the devices described above lie behind the main regulating-valve, and thus only exert an influence on the internal distribution of the steam. Sometimes, however, it is found preferable to omit the main regulating-valve and to depend for the regulation of the turbine on the arrangement of valve-gear described above.

Having now described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. A fluid-pressure turbine proportioned to work economically at the lighter loads, in combination with passages leading from the pressure-chest to intermediate stages of the turbine, the openings to such passages being automatically regulated by a valve, whereby the turbine works economically at the higher loads also, substantially as set forth.

2. A fluid-pressure turbine proportioned to work economically at the lighter loads, in combin ation with passages leading from the steamchest to intermediate stages of the turbine, the openings to such passages being automatically controlled by a valve Worked direct from a governor, whereby the turbine works economically at the higher loads also.

3. Afiuid-pressure turbine proportioned to work economically at the lighter loads, in combination with passages leading from the pressure-chest to intermediate stages of the turbine, the openings to such passages being automatically controlled by a valve caused to' move by the variations of pressure in the pressure-chest due to the action of a governer, whereby the turbine works economically at the higher loads also.

4. A fluid-pressure turbine proportioned to work economically at the lighter loads, in combination with passages leading from the pressure-chest to intermediate stages of the turbine, the openings to such turbines being automatically controlled by a valve attached to a spring-controlled piston moving according to the variations of pressure in the steamchest due to a governor, whereby the turbine works economically at the higher loads also.

5. A fluid-pressure turbine proportioned to work economically at the lighter loads, in combination with passages leading from the steamchest to intermediate stages of the turbine, the openings to such passages being controlled by a valve connected to a spring-controlled piston moving in a cylinder, the pressure on such piston being regulated by a throttle-valve actuated by a governor, whereby the turbine works economically at the higher loads also.

6. A fluid-pressure turbine and in combination, a pressure-chest, a conduit leading therefrom to an intermediate part of the turbine and a valve in the chest controlling the said conduit said valve having an opening therethrough allowing communication between the said pressure-chest and the end of the turbine, substantially as described.

In witness whereof I have hereunto set my hand in presence of two witnesses.

CHARLES EUGEN LANCELO'I BROWN. Vitnesses:

Furry. FINN, C. BAUMANN.

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