US1935451A - Multiple stage steam turbine - Google Patents

Description

Nov. 14,1933. W. A, @NES 1,935,451

MULTIPLE STAGE STEAM TURBINE w. A. JoNEs MULTIPLE STAGE STEAM'TURBINE Nav. 14, 1933.

Filed Aug. 29, 1.952 4 sheets-sheet is /////f//////////V/////////V/.

INVENTOR Nov, 14, 1933.

W. A. JONES Filed Aug. 29 1952 4 Sheets-Sheet 4 Patented ev.. i4, rees A Les MULTIPLE STAGE STEAM TURBINE irlilliam Anthony Jones, West New Brighton,

rApplication August 29,

6 Claims.

When steam expands adiabically it may perform useful work which is the mechanical equivalent of the difference in total heat of the steam before and after the expansion. The total heat of the steam is the sum of that due to the latent heat and that due to the sensible heat.

At high pressure saturated steam has been latent heat and more sensible heat than does saturated steam at lower pressure.

When steam expands through a nozzle attaining a velocity of ow and this velocity is dissipated by friction into heat in a closed vessel, as in a calorimeter, the energy of motion is converted into heat and the resulting temperature of the steam at the lower pressure depends upon how much moisture if Aany is in the steam before expansion.

If no moisture is initially present, the steam at the lower pressure, in general, will be superheated somewhat above the temperature of saturated steam at the lower pressure. Calorimeters made on this principle enable us to determine small amounts of moisture in steam at high pressure.

When steam expands within a multiple stage turbine, it rst loses its superheat, if any, and then part of its latent heat with resulting condensation of part of the steam into water.

In the later stages of the multiple stage turbine this water does not attain the velocity which the expanding steam attains and as a result the water is churned by the turbine blades withaccompanying friction which tends to reevaporate the water as in a calorimeter, so that the difference in total energy of the steam, before andafter passing through the turbine, which is equivalent to the mechanical work performed, is less than it otherwise would be.

In the past engineers have soughtto avoid this condition, first; by using a high degree of superheat in the entering steam to prevent condensation in the early stages of the turbine, and second, by resuperheating the steam at a lower pressure to prevent condensation in the later stages of the turbine.

This practice does not decrease the total heat per pound of steam that is discarded in the exhaust, as is obviously necessary for the highest efficiency, and it has the further disadvantage of requiring expensive apparatus and space and much piping, which causes loss of pressure further decreasing eciency, and of requiring special materials to withstand the very high temperatures used.

Resuperheating the steam as described also has 1932. serial No. 630,867

(ci. cri-7s) the disadvantage that the volume of the low pressure steam is materially larger than it would be if part of the steam was condensed and the steam was not resuperheated and this in turn requires larger turbines, piping, condensers, more building and more space than would otherwise be required for a given power generated.

My invention takes advantage of the higher eciency of condensation with its smaller volumes, lower temperatures and simpler apparatus by the following means;

When flowing steam containing moisture is deflected and has its direction of motion changed by a surface, any particles of moisture in the steam, by reason of their greater weight and inertia, tend to continue their motion in straight lines and are brought into intimate contact with the deecting surface.

If the deflecting surface is maintained at a temperature slightly above the boiling point of water at the particular pressure of the flowing steam at that part of the turbine, then the moisture will be reevaporated into steam.

The fact that a very slight difference in temperature between a surface and a vapor, enables a great quantity of heat to be imparted to the surface by condensation of the Vapor when the surface is at a lower temperature, or from the surface by evaporation of a liquid into vapor when the surface is at a hig'lr temperature, enables us to condense steam at'i'one side of a plate of metal 'and to evaporate water into vapor at the other side of the plate of metal with a very slight' difference in temperature between the vapors on the 'two sides of the plate.

In my invention the deflecting vanes of a turbine are heated by steam of a higher pressure than the owing steam taken from the multiple sage steam turbine at a stage above that of the `owing steam, with the result that as the steam ows through the many stages of the turbine, these heated vanes are always hotter than the steam which flows in contact with their surfaces.

These heated vanes are at a lower temperature than the heating steam. v

The heated vanes are hotter than the owing steam and cooler than the heating steam so that they condense 'steam at one of their surfaces and evaporate water at their other surface, thus permitting'the condensation of part of the steam as it flows through the turbine and keeping the resulting water separate from the flowing steam so that the water is not churned by the turbine blades and reevaporated into steam.

It is Qf. Course possible to use high pressure liti steam to maintain the temperature of the deiiecting surfaces but to do so does not give an emciency as high as is attained -by using steam from a higher stage of the turbine because it discards more heat in the exhaust. lit would also require stronger construction.

Using high pressure live steam for heating the hollow vanes does not take advantage of the mechanical work which that steam might do before it is used for heating. When steam for heating the deiiecting surface is taken from a higher stage of the turbine, that steam has already imparted some of its energy to the turbine in the form of mechanical work, before it imparts the remainder of its available energy in the form of heat to the deflecting surfaces.

Keeping the water, resulting from condensation of the steam, separate from the steam, has the further advantage of decreasing the erosion of the turbine blades which occurs in the lower stages of existing turbines, where most water is. present in the steam and particularly at their outer radius where water is concentrated by centrifugal action as it passes through the turbine.

Referring to the accompanying drawings:

Fig. 1 is a vertical longitudinal section of a multiple stage steam turbine illustrating my invention.

Fig. 2 is a part section on line AA of Fig. 3 through moving blades and steam heated hollow stationary vanes, at a larger scale.

Fig. 3 is an enlarged part of Fig. 1, showing a section through the casing, moving blades and Fig. 7 is a part section on line DD of Fig. 6

of a steam heated stationary vane showing welded joints.

Fig. 8 is a part section on line EE of Fig. 6 of a steam heated stationary vane showing welded joints.

' Fig.9 is a part section on line FF of Fig. 6 of a steam heated stationary vane showing welded joints.

Fig. l0 is a diagram in which line, Bil-3l, represents the steam velociy entering the wheel, line, 32-33, represents the velocity of the wheel, line, Eil-434, equal to line, 31-35, is relative velocity of steam to wheel entering and leaving the wheel, line, Sli- 35, represents velocity, relative to the earth, oi steam leaving the wheel and entering the space between the following stationary vanes where the steam again acquires velocity at the expense oi' pressure and heat.

Fig. l1 is a part longitudinal section through moving blades and sationary vanes of a multiple stage turbine of the usual construction with cylindrical, instead of conical, surfaces at the inner and outer radii of the steam passages in the wheel resulting in more irictionand eddies in the steam flow and generating more heat, with loss of pressure, than the coninuous conical surfaces of my invention.

Fig. l2 is a Mollier diagram for convenience in visualizing the increase in' efficiency resulting from keeping the water resulting from condensation separate from the flowing steam and, in.

wearer visualizing the increase in efficiency resulting from the construction shown in Figs. l, 3, and 4 eliminating ripples in steam flow resulting from the crooked passages and consruction shown in Fig. 1i.

Like reference characters indicate like parts in the several views.

In the turbine shown, which I have chosen for purposes of illustration, a shaft, l, supported by bearings, 2 and 3, carries rotating discs, 4, on whose edges moving blades, 5, are driven by jets of steam flowing between stationary vanes, 6.

Stationary vanes,V 6, are in the form of curved rectangular tapered tubes formed of curved radial plates, 41 and 42, and circumferential outer and inner plates, 43 and 44, which are conical.

Plates, 41, are curved to a shorter radius than plates, 42, so that a space, 8, is formed between them and connects space, '7, in piece, 9, outside of stationary vanes, 6, with space, 16, in piece, 11, inside of stationary vanes, 6.

S'ationary vanes, 6, are welded, or otherwise attached, to outer piece, 9, and to inner piece, 1l, and to each other so that spaces, 7, 8 and 10, are completely enclosed and steam within these spaces completely surrounds rectangular tubular stationary vanes, 6.

Pipes, 12, valves 13 and pipes, 14, conduct steam from spaces, 15, beyond rotating discs at one stage to spaces, '7, 8 and l0, at a lower stage, so that rectangular tubular stationary Varies,V 6, of one stage are completely surrounded by steam at a higher pressureA and temperature from. an earlier stage of the turbine.

Pipes, 16, valves, 17, and pipes, 18, at the lower im side of the turbine, connect spaces, 7, of one stage with space, 7, of a lower stage and are available to drain water from condensed steam, from one stage to a stage below.

Valves, 13 and 17, will be adjusted to maintain ,the desired pressure in spaces, '7, 8 and 10, and so that only water from condensed steam and no steam itself'will flow through valve, 17.

Evidently steam within spaces, '7, 8 and 10, surrounding vanes, 6, will be at a higher pressure and temperature than the flowing steam which drives the turbine blades, 5, at that point and the metal of the stationary vanes, 6, at that point will be at an intermediate temperature, so that steam in spaces, 7, 8 and l0, will be condensed supplying heat to prevent condensation in the owing steam and evaporating any moisture that may be in the flowing steam. This is the object desired.

Steam enters the turbine through ports, 20, and for high ratings through ports, 21. Steam `is exhausted to space, 22.

Condensed steam, forming water separate from the owing steam, is finally discharged through valves, 19, and ordinarily will be returned to the boiler feed. t

If parts are made of steel they may be conveniently joined by electric welding, which is Vthe construction contemplated in the particular representation shown. Edges may be beveled so that the welding metal will completely seal the joints between pieces, 9, 11, 41, 42, i4 and 45, as shown.

Evidently the number of vanes per stage and the length of the'vanes axially may be varied to give somewhat more than the required heating surface for each stage.

In the Mollier diagram, Fig. 12, line AF represents the adiabatic expansion of steam, Without friction, from about 386 pounds absolute pres- 150 inattesi minus 877.86 divided by i350 equals about 35' per cent.

Line ABC represents the expansion of this steam to the same final pressure in a turbine where'water of condensation is not separated from the owing steam and as a result of friction the exhaust is assumed to have 982 B. t. u. per

pound above 32 degrees F. giving an emciency about equal to 1350 minus 982 divided by 1350 equals aboutv 27.25 per cent.

Mne ABD represents the expansion of this steam to the same iinal pressure in a turbine .where water of condensation is kept separate from the nowing steam as described in this application and the exhaust is assumed to have 956 B. t. u. per pound above 32 degrees giving an emciency about equal to 1350 minus 956 divided by 1350 equals about 29.2 per cent.

27.25 divided by 29.2 gives .935 as much steam for line ABD as for line ABC for the same power.

Line AE represents the expansion of this steam to the same nal pressure in a turbine where water of condensation is lrept separate from the howling steam as described and with an assumed friction of flow one half as great as that for line AD due to elimination of ripples, shown in Fig. l1, and using the construction shown in Fig. 3, so that the exhaust has only 917 B. t. u. per pound giving an eiciency about equal to i350 minus 917 divided by 1350 equals about 32.07 per cent.

27.25 divided by 32.07 gives 85 per cent as much stm for line AE as for line ABC for a given power.

The foregoing ngures are assumed simply as an illustration.

l claim:

1. In combination, in a multiple stage. steam turbine, a steam inlet, a shaft with bearings, a casing, rows of moving blades carried by the shaft, rows of hollow stationary vanes between the rows of moving blades, the stationary vanes and the moving blades being formed between concentric inner and outer surfaces whose longitudinal sections are approximately straight lines, connections conducting some steam from a separate upper stage to heat the hollow vanes of each lower stage where it is condensed and supplies heat to those hollow vanes and thereby `to the owing steam of lower pressure and temperature at that point, connections conducting only the water from this condensation, and no steam, from each row of' hollow stationary vanes insuccession to rows of hollow stationary vanes below, valves in the water connections, whereby the flow can be controlled, valves in the steam connectionan whereby the heating of the vanes can be controlled and changed to suit the rate at which the turbine is working and the point at which saturation of the steam occurs.

2. 1n combination, in a multiple stage steam turbine, a steam inlet, a shaft with bearings, a nu rows of moving blades carried by the t, rows of hollow stationary vanes between the rows of moving blades, connections conduct-u ing some steam from a separate upper stage to heat the hollow vanes of each lower stage where it is condensed and supplies heat to those hollow vanes and 'thereby to the flowing steam of lower pressure and temperature at that point, connections conducting only the water from this condensation, -and no steam, from each row of hollow stationary vanes in succession to rows of hollow stationary vanes below, valves in the water connections, whereby the flow can be controlled, valves in the steam connections,'whereby the heating of the vanes can be controlled and changed to suit the rate at which the turbine is working and the point at which saturation of the steam occurs.

3. 1n combination, in a multiple stage steam turbine, a steam inlet, a shaft with bearings, a casing, rows of moving blades carried by the shaft, rows of hollow stationary vanes between the rows of moving blades, connections conducting some steam from a separateupper stage to heat the hollow vanes of each lower stage where it is condensed and suppliesheat to those hollow vanes and thereby to the flowing steam of lower pressure and temperature at that point, connections conducting only the water from this condensation, and no steam, from each row of hollow stationary vanesin succession to rows of hollow stationary vanes below, valves in the water connections, whereby the fiow can be controlled.

t. In combination, in a multiple stage steam turbine, a steam inlet, a shaft with bearings, a casing, rows of moving blades carried by the shaft, rows of hollow stationary vanes between the rows of moving blades, connections conducting some steam from a separate upper stage to heat the hollow vanes of each lower stage where it is condensed and supplies heat to those hollow vanes and thereby to the flowing steam of lower pressure and temperature at that point, connections conducting only the water `from this con= densation, and no steam, from each row of hollow stationary vanes in succession to rows of hollow stationary vanes below. r

5. 1n combination, in a multiple stage .iw turbine, a steam inlet, a shaft with bearings, a casing, rows of moving blades carried by the shaft, rows of hollow stationary vanes between the rows of moving blades, arrangements by which at each lower stage a portion of the expanding steam is separated from the main body casing, rows of moving blades carried by the shaft,

rows of hollow stationary vanes between the rows Aof moving blades, connections conducting some 3,-:

ing steam, in succession to the hollow stationary of each stage below.

1|: f i A i ANTHONY JONES.

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