Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROI~ND OF THE - INVENTION
This invention is concerned with a new class
of heat engines where the working fluid, for example
steam, is used in its two-phase region with vapor and
liquid occurring simultaneously for at least part of the
cycle, in particular the nozzle expansion. The fields
of use are primarily those where lower speeds and high
torques are required, for example~ as a prime mover
driving an electric generator, an engine ~or marine and
~o land propulsion, and generally as units of small power
output. No restrictions are imposea on the heat source,
which may be utilizing ~ossil fuels burned in air, waste
heat, solar heat, or nuclear reaction heat etc.
The proposed engine is related to existing
steam tu.rbine engines; however, as a consequence of using
large fractions of liquid in the expanding part of the
cycle, a much smaller number of stages may usually be
required, and the tuxbine ma.y handle liquid only. Also,
the thermodyn.amic cycle ~ay be altered considera~ly from
the usual Rankine cycle, inasmuch as the expansion is
taking place near the liquid line of $he temperature~
entropy diapgram, and essentially parallel to that line,
as described below. In contrast to other proposed
two-phase engines with two components (a high-~apor
pressure component and a low-vapor pressure component,
see U.S. Patents Nos.3,879,949 and 3,972,195), the present
engine is limited to a single-component fluid, as for
example water, the intent being to simplify the working
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fluid storage and handling, and to improve engine
reliability by employing well proven working medla of
high chemical stability.
SUMMARY OF TE~E INVENTION
It is a major object of the invention to provide
an economical engine of low capital cost due to simple
construction, low fuel consum~tion, high reliability, and
minimum maintenance requirements.
The ob]ective of low fuel consumption is achieved
by "Carnotizi~g"the,leat engine cycle in a fashion similar
to regenerative feed-water preheating, which consists
in extracting ~xpanding steam from the turbine in order
to preheat feed-water by condensation of the ext~acted
steam. Since the pressure of the heat emitting condensing
vapor and the heat absorbing feed-water can be made the
same, a direct-contact heat exchanger may he used, which
is of high effectiveness and typically of very small size.
Further, and in contrast to the co~ventional
regenerative feed-water heating scheme~ the expanding steam
is of low quality, typically o~ lO to 20~ mass fraction
o vapor in the total wet mixture flow. As a result, the
enthalpy change across the nozzle is reduced to such a
degree that a two-stage turbine, for example, is able to
handle the entire expansion head at moderate stress levels.
By way of contrast, a comparable conventional im~ulse
steam turbines would require about ~ifteen stages. The
turbine itself may consist of a liquid turbine that may
be combined with a rotary separator in the manner to be
described.
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These and other objects and advantages oE the
inven-tion, as well as the details of an illustrative
embodiment, will be more fully understood from the
following description and drawings, in which:
i DRAWING DESCRIPTION
Fig. 1 is an axial vertical elevation, in
section, schematically showing a two-stage liquid turbine,
with recuperator;
Fig. 2 is a vertical section showing details
of the Fig. 1 apparatus, and taken along the axis;
Fig. 3 is an axial view of the Fi~. 2 apparatus;
Fig. 4 is a flow diagram;
Fig. 5 is a temperature-entropy diagram; and
Fig. 6 is a side elevation of a nozzle, taken
in section.
~ETAILED DE5CRIPTION
Referring first to Fig. 1, the ~rime mover
apparatus shown includeslfixed, non-rotating structure
19 including a casing 20,1 an output shaft 21 rotatable
about axis 22 to drive and do work upon external device 23;
rotary structure 24 with~h the casing and direc~ly connected
to shaft 21; and a free w~eeling rotor 25 within the casing.
A bearing 26 mounts the ~otor 25 to a casing flange 20a;
a bearing 27 enters sha~t 21 in the casing bore 20bi
~5 bearings 28 and 29 mount ~-tructure 24 on fixed structure
19; and bearing 30 cente~s rotor 25 relative to structure 24.
In accordance ~ith the invention, firs-t nozzle
means, as for example no~zle box 32, is associated with
fixed structure 19, and is supplied with wet steam for
0 expansion in the box. As also shown in ~igs. 2 and 3, the
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nozzle box 32 typically includes a series of nozzle
segments 32a spaced about axis 22 and located between
parallel walls 33 which extend in planes which are normal
to that axis. The nozzles define venturis, including
convergent portion 34 throat 35 and divertent portion 36.
Walls 33 are integral wi~h fixed structure 19. Wet
steam may be supplied from boiler BB along pa~hs B 5 and
136 to the nozzle box. Figs. 2 and 3 shows the provision
of fluid injectors 37 operable to inject fluid such as
water into the wet steam path as defined by annular manifold
39, immediately upstream of the nozzles 32. Such fluid
may be supplied via a fluid inlet 38 to a ring-shaped
manifold 39 to which the injectors are connected. Such
in~ectors provide good droplet distribution in the wet
steam, for optimum turbine operating efficiency, expansion
of the steam through the nozzles accelerating the water
droplets for maximum impulse delivery to the turbine
vanes 42. A steam inlet is shown at 136a.
Rotary turbine structure 24 provides first vanes,
as for example at 42 spaced about axis 22, to receive and
pass the water droplets in the steam .in the nozzle means
32. In this regard, the steam fraction increases when
expanding. Such first vanes may extend in a~ial radial
planes, and are typically spaced about axis 22 in circular
2S sequence. They extend between annular walls 44 and 45
of structure 24, to which an outer closure wall 46 is
joined. Wall may fo~m one or more nozzles, two being
shown at 47 in Fig. 3. Nozzles 47 are directed generally
counterclockwise in Fig. 3, whereas noæzles 32 are
directed generally clockwise, 50 that turbine structure 24
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rotates clockwise in Fig. 3. The turbine structure is
basically a drum that contains a ring of liquid (i.e.
water ring indicated at 50 in Fig. 3), which is collected
from the droplets issuin~ from nozzles 32. Such water
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issuing as jets from nozzles ~7 is under pressurization
generated hy the rotation of the solid ring of water 50.
In this manner, the static pressure in the region 51
outwardly of the turbine structure need not be lower than
the pressure of the nozzle 32 discharge to assure proper
liquid acceleration across such nozzles 47. Tne radi~l
vanes 42 ensure solid body rotation of ~he rins of liquid
at the speed of the structure 24. The vanes are also
useful in assuring a rapid acceleration of the turbine
from standstill or idle condition.
Water collecting in region 51 impinges on the
freely rotating rotor 55 extending about turbine rotor
structure 24, and tends to rotate that ro~or with a
rotating ring of water collecting at 56. A non-rotating
scoop 57 extending into zone 51 collects water at the
inner surface of the ring 56, the scoop communicating
with second nozzle means 58 to be described, as via ducts
or paths 1~9-1~63.Accordingly, expanded first stage 1.iquid
(captured by free-wheeling drum or rotor 55 and scooped up
~ pitot opening 5-7) may be supplied in pressuri~ed
state to the inlet of second stage nozzle 58~
Also shown in Fig. 1 is what may be referxed
to as rotary means to receive feed water and to centrifugally
pressurize same. Such means may take the for~ of a
centrifugal rotarY pump 60 mounted as by bearings 61 to -
fixed structure 19. The pump may include a series of
discs 62 which are normal to axis 22, and which are located
within and rotate with pump casing 63 rotating at the
same speed as the turbine structure 24. ~or that purpose,
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a connection 64 may extena ~etween casing 63 and the
turbine 24. The discs of such a pump ~as for example
a Tesla pump) are olosely spaced apart so as to allow
the liquid or water discharge from inlet spout 65 to "
distribute generally uniformly among the individual
slots between the plates and to flow radially outwardly,
while gaining pressure. - .
A recuperative zone 66 is provided inwardly
of the turbine wall structure 24a,to communicate with
the discharge 60a of rotating pump 60, and with the
nozzle box 32 via a series of steam passing vanes 68.
The latter are connected to the turbine rotor wall 24b
to receive and pass steam discharging from nozzles 32,
imparting further torque to the turbine rotor. After
passage be~een vanes 68, the ~team is drawn into direct
heat exchange contact with the water droplets spun-off
fxom the pump 60, in heat exchange, or recuperative
zone 66. Both liquid droplets and steam have equal
swirl velocity and are at equal static pressure in
rotating zone 66~ as they mix therein~
The mix is ~ontinuously withdrawn for further
heating and supply to the first nozzle means 32. For
the puxpose, a scoop 70 may be associated with fixed
structure 19, and extend into zone 6~ to withdraw the
fluid mix for supply via fixed ducts 71 and 72 to boiler
or heater BB, ~rom which the ~luid mix is returned via
path 135 to the nozzle means 32.
The second stage nozzle me~ns 58 receives
. water from scoop 57, as previously descri~ed, and also
steam spill-over from ~pace 66, as via pakhs 74 and 75
Trade Mark
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adjacent tur~ine wall 24c. Such pressurized steam mixed
with liquid ~rom scoop 57 is expanded in the second
nozzle means 58 producing vapor and waterl the vapor
being ducted via paths 78 and 79 to condenser CC. Fourth
vanes 81 attached to rotating turbine wall 24d receive
pressure application rom the flowing steam to extract
energy from the steam and to develop additional torque.
The condensate from the condenser is returned via path
83 to the inlet 65 of pump 60. The water from nozzle
L0 means 58 collects in a rotating ring in region 84,
imparting torque to vanes 85 in that region bounded by
turbine rotor walls 86 and 87, and outer wall 88. ~or
that purpose, the construction may be the same as tha~ o
the first nozzle means 32, water ring 50, vanes 42 and
L5 walls 44-46. Nozzles 89 discharge water from the rotating
ring in region 84, and correspond to nozzles 41. Free
wheeling rotor 55 extends at 55a about nozzles 47, and
collects water discharging from the latter, ~orming a riny
in zone 91 due to centrifugal effect. Won-rotary 5COOp
90 collects water in the ring formed by rotor extent 55a,
and ducts it at 92 to path 83 for return to the TESLA
pump 60.
The cylic operation of the engine will now be
described by reference to the temperature-entropy diagram
of Fig. 5, wherein state points are shown ln capital
letters~ Arabic numerals refer to the compon~nts already
referred to in Figs. 1-3.
Wet steam of condition ~ is delivered from the
boiler to nozzle box 32 (Fig. 1). The special two-phase
nozzles use the expanding vapor for the acceleration of
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the liquid droplets so tha-t the mixtur~ of wet steam
will enter the turbine rin~ 42 (Fig. 3) at nearly
uniform velocity, at the thermoaynamic condition ~ .
The liquid will then separate from the vapor and issue
through the nozzles 47 (Fig. 3) and collect in a rotating
ring in the drum 55 (Fig. 1). The scoop 57 will deliver
collected liquid to the nozzle box 58 at condition ~ .
The saturated expanded stea~ from nozzle 32 at a condition
~ (not shown) in the meantime will drive vanes 68 and
enter the recuperator 66.
In the recuperator the vapor will be partially
condensed by direct contact with feed-water originally
at condition ~ from scoop 90 in Fig. 1, mixed with
condensate as it is returned from the condenser CC. Both
streams of liquid ~at condition ~ ) whether supplied by
scoop 90 or that returning f~om the condenser CC is pumped
up at 60 to the sta~ic pressure of the steam entering
zone 66 (Fig. 1). The heat exchange by direc-t contact
occurs across the surfaces of spherical droplets that
are spun~off from the rotating discs of the TESLA pump,
and into zone-66.
The heated li~uid of condition ~ that is
derived ~rom preheating by the steam and augmented by
condensate formed at condition ~ , is scooped up at 70
and returned to the boiler BB by stationery lines 71 and 72.
The steam which was not fully condensed in the
recuperator 66 will pass on at 74 to nozzle box 58 where
it is mixed with the liquid that was returned by scoop 57.
The ~ixture will be at a condition ~ I corresponding
to the total amount of preheated liquid of condition ~ and
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saturated vapor of condition ~ .
The subsequent nozzle expansion at 58 from
condition ~ to ~results in similar velocities as produced
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in the expansion ~ to ~ in nozzle 32. The issuing jet can
therefore drive the second liquid turbine efficiently at
the speed of the first turhine, so that direct coupling
of the two stages is possible.
The path of the liquid collected in dr~m 25 (Fig.l) a~
the condition E was already described as it is passed on
to the inlet 65 of pump 60. The satura~ed vapor at
condition ~ tnot shown) is ducted at 78 and 79 ~o the -
condenser CC, which is cooled by a separate coolant. The
condensate at condition E is then also returned at 83 to
the pump inlet 65.
Alternate ways of condensing the steam of
condition ~ may be envisioned ~hat are similar to the
method employed herein to condense steam of condition ~
; at intermediatè pressure in the recuperator. The difference
is that a direct contact low pressure condenser will
require clean water to be used for the coolant, so that
mixing with the internal working medium is possible. Such a
liquid coolant will probabl~ best be cooled itself in a
separate conventional li~uid-to-liquid or liquid-to-air
heat exchanger"so that it may be re-circulated continuously
in a closed, clean system.
The turbine engine described in FigO 1 is a
two-stage unit with only one intermediate recu~rator.
An analysis of the efficiency of the thermodynamic cycle
shows that the performance i5 improved amony others by
two factors~
13 increased vapor quality of the steam
trelative mass fractionof saturated steam) -
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2) An increased number of intermediary
recuperators. Since an increase in vapor quality raises
the magnitude o~ the nozzle discharge velocity, a compromise
is called for between number of pxessure stages, allowed
rotor tip speed, and num~er of recuperators. Note that
sa~urated steam may be extracted at equal increments
along the nozzlei at least two recuperators operating at
intermediate pressure levels may be arranged per stage
in order to improve the cycle efficlency without increasing
o the nozzle velocity.
Other types o~ liquid turbines may be used
instead of the particular turbine shown in Fig. 1 and
Pig. 2. See for example U.S. Patents 3,8?9,949 and 3~972,195.
Alsor a more conventional turbine with buckets
.5 around the periphery may be employed and which admits a
homogeneous mixture of saturated steam and satùrated water
droplets.
Good ef~iciencies for such turbines are obtainable
if the droplet size of the mixture emerging from the nozzle
!0 is kept at a few microns or less.
To achieve the latter, the con~erging-diverging
nozzle may ~e designed with a sharp-edged throat as a
transition from a straight converging cone 200 to a
straig~.t divera,~ng cone 201. See Fig. 6 showing such a
~5 noz~le 202.
Fig. 1 also shows annular partition 95 integral
with xotor 55, and separating rotary ring of water 56 from
rotary ring 91 o~ water.
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