US1027698A - Marine steam-turbine. - Google Patents

Description

G. G. CURTIS. MARINE STEAM TURBINE. APPLIUATION FILED MAY 15, 1911.

Patented May 28, 1912.

3 SHEETS- SHEET 1.

r P /n7/. Attorneys.

W i nesses C. G. CURTIS.

MARINE STEAM TURBINE.

211101111011 FILED MAY 15, 1911. -1 ,O27,698.

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A 1 QQZW G. G. CURTIS. MARINE STEAM TURBINE. APPLIOATION FILED MAY 15, 1911.

Patented May 28 1912.

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PATENT onricn MARINE STEAM-TURBINE.

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Specification of Letters Patent Patented May 28, 1912.

Application filed m 15, 1911.. Serial No. 627,113.

My inventlon relates to that arrangement :of marine steam turbines in which four propeller shafts are employed with two inde- 'endent power equipments each distributed etween two or the shafts; and my object is to reduce for this purpose a construction an arrangement of turbine elements which will give a high eliiciency' and equal distribution ofpower at both high and low power and in which the propeller thrust on each shaft will be wholly or largely neutralized 'et ell substantial roads in accordance with the principles set forth in my applications Serial Numbers 593,159, 593,160 end 593,161, filed November 19, 1910. v

In the drawing Figure 1 is a plan view showingthe arrangement of elements of the go-ahead and backing turbines on two shafts; Fig. 2 is e longitudinal vertical sec tion of the upper half of the high pressure element of the go-eheud turbine. is a view'siinilzir to Fi -2 of the intermediate "pressure element 0 the go-ahesd turbine;

Fig. 4 is a similar view of the low ressu're element of the go-aheud turbine am of the low pressure element of the backing turbine; Fig. 5 is a similar View of thehigh pressure backing turbine; and Figs. 6 and 7 are, re spectively, a radial longitudinal section on line w-q and a development, of nozzles and vanes, s owing the use of guide passages to conserve the residual velocity in the wheel stages of the high pressure element of the go-ahead turbine under cruising conditions. Referring particularly to Fig. 11 A and B are the two propeller shafts, C, D, and E are respectively the high, ntermediate and low pressure elements of the .go head turbine, while F and G are respectively the high and low pressure elements of the bucking turbine. The thrust collars 'on the. shafts A, B are shown at .7, 8. The pipes. 9 convey the steam fromtheboiler to the high pressure go-ahead element 0, pipes 10co'nnect O and D, and pipe 11 connects Dand E, these three elements taking the steam in succession. The pipes 12 convey the boiler steam to the backing-high pressure element F, and pipes 13 connect Fund G, which take the steam in succession. The exhaust opening 14 is connected with the condenser. The

high and low pressure go-ahead elements G, E, and the low pressure backing element Gr aremounted on the shaftA, while the intermediate pressure go-ahead element D and the high pressure bucking element F are mounted on the shut't B. The steam pus sages or" the go-ahead elements are so pro-' port-ioned that at full load the'elements C and E on the shaft A will develop SllbSl'zlIltially the some power as the element D on the shaft B, and likewise the hacking elements F and G are designed to develop substantielly the same power at full load The go-uhead high pressure element C (Fig. 2) is preferably composed of a nu1nber of impulse wheel stages, with partial peripheral steam admission, and having u plurality of velocity steps in each pressure stage. For simplicity of illustration, only the first and lost sets pt moving and stationury vanes in each stage are shown in Fig. 2, and this is also trueof all figures of "the drawing similar to Fig. 2. The moving vanes ure as usual mounted on wheels or desire 15 carried by the shutt. the stationary vanes being carried. by the shell. The stages are separated by diaphregnis 1.0 which carry 1 the nozzles, the first stage nozzles opening" through the head of the shell in the steam chest 17. Valves 18 and 18'(shown slide valves) Figs; 2 and 7, shut off sections of the nozzles of the several stages.

As shown in Fi s. 6 and 7, there pro;

vided between the lu st lrow ofmovingva-nes I of each stage and the nozzles of the suceeed ing stage a guide passage 19 composed. of top and bottom wells. sages direct the steam, discharged by" the vanes ofeachistege into thenoiizle of the next stage andthereby conserve the residiml yelocity. The guide passages are useful in improving the efiiciency at low or cruising speeds, since the vane velocity at low speed is not suilicient to abstract-the steam velocity, and hence it is only necessary that these guide passages should be placed opposite the sections of the successive nozzles which are open zit-these speeds.

As shown-in Fig 7, the

are placed only'i'nthelinc of steam from the nozzle sections-whicliure not "con osi These. guide pastrolled by valves, the other nozzle Sections being close at cruising speed. The turbine element C being preferably composed wholly of wine elements havin no difference in pressure on the opposite sides of the wheels, there is no axial thrust in this element ex cept such as may be produced by differences in shaft areas (if any) at the opposite ends of the element. The balancing of the propeller thrust is provided for by the construction of the low ressure element E on the same shaft which will be presently described.

The go-ahead intermediate pressure element- D ig. 3) is preferably provided with an initial wheel stage having velocity steps, but this wheel stage may be omitted. The nozzle sections for this wheel stage 20 (when used) are controlled by valves 21 similar to the valves 18 and 18. Following the wheel stage 20 is a drum stage 22, having preferably a number of single velocitystep impulse, pressure stages, .wlth complete peripheral steam admission. The drum of the drum stage 22 is connected with the shaft by a steam-tight pressure head 23 v which carries the difference in pressure produc'ed by all the pressure stages on the drum and gives a thrust opposed to the propeller thrust on the shaft B. Following the direct drum stage 22 is a reversed drum stage 24 having preferably a number of single velocity-step impulse, pressure stages, with complete peripheral steam admission, and con nected with the shaft by a steam-tight pressure head 25 which is subject to the diiference in pressure produced by all the pressure stages on the drum and exerts an axial thrust in the same direction as the propeller thrust. The two drum stages are separated by a diaphragm. 26 supported by the shell,

and pipes 27 connected with the shell forward of this diaphragm and extending to the rear end of the shell, carrying the steam from the direct drum stageto the reversed drum stage. The steam passages are so pro portioned that, taking into consideration the axial thrusts produced by the shaft,- thrust 1 areas, the thrust produced by the head 23 of the direct drum'stage will be enough greater than the thrust produced by the head 25 of the reversed drum stage to practically neutralize the propeller thrust at all substantial loads, as explained in my appli cations referred to. a

The go-ahead low pressure element E (Fig. 4) is composed of a single direct d1 um stage 28 having preferably a number of single velocity-step impulse, pressure stages, with complete peripheral admission, the ,drum being connected to the shaft by a steam-tight pressure head 29. This ressure head gives an axial thrustwhich, ta ring into consideration the thrusts produced by the shaft thrust areas, practically neutralizes the propeller thrust on the shaft A at all substantial loads. No reverse drum stage is necessary because the steam pressure is lowered to such a point when it reaches the element E that a single pressure head of suitable area will give the desired result.

As has already been stated, the steampassages of the three go-ahead turbine elements are so proportioned that at full load the high and low pressure elements on one shaft will. develop substantially the 'same power as the'intermediate pressure element on the other shaft. The full power condition is secured when all the stage-valves are open. By closing the stage valves in the high pressure element, the great pressure drop which would take place in this element when the steam flow is reduced at cruising power, if all the nozzles are left open, can

be prevented. I have found that by a proper adjustment of these valves the pressure distribution in the three go-ahead elements can be made such that substantially equal power will be developed on the two shafts at cruising power. The use of a wheel stage and nozzle valves in the intermediate pressure element also aids in securing this result, although an approximationto the result can be secured without this feature.

The high pressure backing element F on the shaft B (Fig. 5) is composed of two or more partial admission wheel stages 30 and a complete admission drum stage 31, while the lowpressure backing element G on the shaft A (Fig. 4) is composed of out! or more partial admission wheel stages 32 and a complete admission drum stage 33. The element F has a separate shell, while the element G, may be inclosed in a continuation ,of the shell of the go-ahead element The dri'ims of the backing elements areconnected with the shafts by steam-tight ressure heads 34, 35,which produce axial t rusts opposed to the thrusts of the propellers in backing.

The drums of the several go-ahead and backing elements, instead of operating on the impulse principle may be provided with vanes operating on the reaction principle, in

which case the axial thrusts produced by the differences in pressure on the rotating vanes would be taken into consideration in making provision for neutralizing the propeller thrust; and it should also be understood that, in respect to certain features of the invention hereinafter .claimed, and except where otherwise indicated by the language or subject-matter of the claims, the high pressure, go-ahead element may be a reaction element,

on'one shaft and an intermediatepressure turbine element on the other shaft, thelat- 'ter having reversed drum stages, substantially as set forth. a

. 2. In a marine steam turbine, the combinationwith two propeller shafts, of high and low pressure turbine elements on one shaft and an intermediate pressureturbine element on the other shaft, the latter having reversed drum set forth. I

3. In a marine steam turbine, the combination with two propeller shafts, of a prime stages, substantially as mover and a .low pressure turbine element on one shaft and an intermediate pressure turbine element on the other shaft, the intermediate pressure turbine element having reversed drum stages and adapted to develop at full power substantially "the same power as the combined power of the power eleinenitls on the first shaft, substantially as set 'ort r 4.. In a marine steam turbine, the-combination with two propeller shafts, of high and low pressure turbine elements on one shaft and an intermediate pressure turbine element on the 'othershaft, the latter having reversed drum stagesand adapted to develop at full power substantially the same power as the combined power of the high and low pressure elements on the first shaft, substantially as set forth.

5. In a marine steam turbine, the combination with two propeller shafts, of high and ,low pressure turbine elements on one shaft, means for producing an axial steam 7. In a marine steam turbine, the conibi nation with two propeller shafts, of an intermediate pressure turbine element on one shaft, a high pressure 'turbineelement on the other shaft composed of wheel impulse stages separated by diaphragms, and a low pressure turbine element on the same shaft as the high pressure element and composed of a single drum stage opposing the propeller thrust, siibstantlally asset forth.

8. In a marine steam turbine, the combination with two pro ller shafts, of high and low pressure tu-r ine elements on one shaft composed .respectively of wheel im pulse stages, and a single drum'stage, the latter opposing the propeller thrust, and an intermediate pressure element on the other shaft having reversed drum stagesv producing a resultant thrust opposed to the propeller. thrust, substantially as set forth.

9. In a marine steam turbine, the combination with two propeller shafts, of high and low ressure turbine elements on one shaft, an intermediate pressure turbine element on the other shaft, such elements being proportioned to produce substantially equal power on'the two shafts at full powe and means controlling the pressure dlstrlbution at cruising power 1n each of the several turbine elements so that substantially equalpower is developed on the two shafts at cruising power, substantially as setforth.

10. In a marine steam turbine, the combination with twoj: :1 more impulse wheel stages, of stage nola'zle" valves for each stage, controlling part of the nozzles, cruising nozzles not controlled by the stage valves, and guide passages between the moving blades of each stage and the cruising nozzles of the next stage to \';onserve the residual velocity at cruising speeds, substantially as set forth.

11. In a marinesteam turbine,the combination with two propeller shafts, of two backing turbine elements mounted on the respective shafts and taking the steam flow in succession, the high pressure backing element having one, or more wheel impulse stages and a drum stage opposing the propeller thrust and the low pressure backing element having a drum stage opposin the propeller thrust, substantially as set orth.

12: In a marine steam turbine, the combination with two propeller shafts, of two backing turbine elements mounted on the respective shafts and taking the steam flow in succession, each of such backing turbine elements having .one 'or more wheel impulse stages and a drum stage opposing the propeller thrust, substantially as set forth.

This specification signed and witnessed this twelfth day of May, 1911.

CHARLES G. CURTIS.

Witnesses J on L. Loreen, RUDOLPH J. GUs'rArsoN.

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