Improvements in Steam Turbines.
Year: 1891

page_text: Date of Application, 21st Mar., 1891
Complete Specification Left, 21st Jan., 1892'--Accepted, 27th Feb., 1892
PROVISIONAL SPECIFICATION.
Improvements in Steam Turbines.
I, The Honourable CHARLES ALGERNON PARSONS, of Heaton Works,
Newcastle-on-Tyne, in the County of Durham, Engineer, do hereby declare the
nature of this invention to be as follows:-
My invention relates to the application of steam or other jacketing to steam
turbines and its object is to improve the efficiency and economy of steam turbines
by removing certain sources or causes of loss of effect which I have discovered can
be removed by steam or other hot jacketing or superheating.
In steam jacketing the cylinders of reciprocating steam engines, as commonly
practised, the main object is to prevent initial condensation and subsequent
re-evaporation and it is commonly understood that the initial condensation is
mainly due to the oscillations of cylinder temperature brought about by the cooling
action of the expansion proceeding in the cylinder during the stroke. The cylinder
and cover surfaces thereby become cooled towards the temperature of the discharge
steam and the entering high pressure steam at the beginning of a new stroke
becomes condensed to heat up the walls again. This condensed water re-evaporates
as the stroke proceeds and so great loss is caused and further cooling of the
cylinder walls occurs.
In steam turbines where the steam is caused to flow through vents or blades and
acts by its momentum to cause the wheels to revolve, no cut off is necessary to
secure the working of the machine and the expansive action of the steam. The
temperature and pressure of the steam in contact with the parts of the engine
remains constant or approximately constant for long periods covering many
revolutions of the engine, and there is consequently no re-condensation and
re-evaporation of the kind that occurs in piston or reciprocating engines.
A little loss may occur by the conduction of heat from the hot part of the
turbine to the cooler part due to the metallic contact or continuity of the rings and
case of the turbine, but that loss is inconsiderable. I have however discovered
that a great and totally different loss of power occurs from the supersaturated
condition of the steam consequent upon the work done by it upon the blades in
moving them and driving the engine. This supersaturated condition in which a
larger or smaller proportion of water is condensed has the effect of impeding the
flow of steam through the vents, blades and passages and by the introduction of
liquid instead of gaseous friction between the fixed and moving parts causes a
serious retarding influence on the turbine wheels, discs and rings of blades. The
great loss of power that this invention is intended to remove is not due to diminished
volume of steam caused by partial condensation of the active steam and subsequent
re-evaporation but that loss due to the liquid friction of water as described which
liquid friction it is obvious when acting between fixed and moving surfaces is many
times greater than that of gaseous steam at ordinary pressures and temperatures.
My invention may be applied in various ways keeping in view that the main
object is to prevent the admission of liquid water to the turbine or formation of
liquid water within the turbine; I may accomplish this object for example by
superheating the steam before admission in order that the temperature may be
sufficiently elevated for the steam to sustain the various losses of heat without
liquifaction but this method would involve a temperature so high as to be
detrimental to the surfaces of the engine or it might cause distortion or damage so
that I do not apply it except in special circumstances.
I prefer to steam jacket the engine in such a way as to supply the heat as
required to maintain the steam in a gaseous condition during its course and prevent
condensation without great excess of temperature above the point of saturation.

page_text: The jacket may be continuous or it may be arranged in successive steam jackets or
heaters to dry and moderately superheat the steam on its passage from one set of
turbines to the next and a sufficient surface and number of heaters is provided to
prevent condensation.
By either the continuous or the discontinuous method I prevent condensation
without the necessity of dangerously superheating the steam.
For these arrangements I may obviously use jacket steam drawn from the main
boiler or an auxiliary boiler at any or a higher pressure than the main boiler. I
may also jacket with heated liquids kept at a regulated temperature and suitably
heated and regulated. I may likewise apply heated gas, the products of com-
bustion or gases from a flame of coal or other gas or solid. Sometimes too I may
use liquids and solids such as caustic soda, acetate of soda or other substances
having considerable absorptive properties for heat which on cooling continue to
give out heat at nearly constant temperature for long periods. In all cases
however, whatever be the heating arrangements I proportion the thickness of
metal and the absorbing surfaces and transmitting metal in such manner in relation
to the turbines as to provide the necessary transmission of heat to secure the object
of the invention. In applying my invention to radial flow steam turbines I so
arrange the guide rings or casing containing the guide rings of blades that they
shall be more or less surrounded with high pressure steam by which they may he
heated and so transmit heat through their substance and through and along the
blades to the working fluid. I may hollow, core or drill out cavities in the discs,
rings or case to contain the jacket steam and increase the effective surface exposed
to it. In all cases I supply the jackets with steam and drain off in the most
convenient way. I sometimes arrange to jacket the rotating wheels or rings as
well as the stationary ones by providing them with suitable hollows by coring,
drilling or other process to receive jacket steam and in such a construction I
introduce the jacket steam and drain off water of condensation by means of a hollow
rotating spindle.
In another construction of guide rings I form the rings to abut each other by
spigot and fawcet joint or by faced joint only and build up a compound cylinder
which I hold together by longitudinal bolts and so enclose the working discs or
rings of blades. This built up cylinder I enclose within a case containing high
pressure steam from which steam the cylinder receives and transmits heat to the
working steam and moving discs or rings of blades within. The guide rings
forming the built up cylinder may be hollow drilled or cored out to increase the
effective heat absorbing surface and diminish the thickness of metal through which
heat is to be transmitted.
In this construction each ring forming part of the cylinder may be cast hollow
and each may be connected to the others and to the supply of jacket steam and so
arranged as to drain into a common drain or the rings may be cast solid and
brought into contact with an arrangement of pipes, containing jacket steam.
I may simply jacket the rings externally and rely upon the conductivity of the
metal to carry the necessary heat to the working parts but this arrangement I
prefer for small turbines where the lineal dimensions are not great.
In these constructions I may increase my heat absorbing surfaces in contact
with the jacket steam by casting or forming webs, ribs or grooves which present
an extended surface to the hot steam and in the case of ribs or webs I may perforate
them to further increase the absorbing surface.
In parallel or approximately parallel flow steam turbines I adopt an equivalent
arrangement such as casting the case hollow to contain jacket steam, the heat being
conveyed by conduction from the case to the rings of blades or I adopt other
convenient methods such as I have herein before indicated.

page_text: COMPLETE SPECIFICATION.
Improvements in Steam Turbines.
I, The Honourable CHARLES ALGERNON PARSONS, of Heaton Works,
Newcastle-on-Tyne, in the County of Durham, Engineer, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
My invention relates to the application of steam or other jacketing to steam
turbines, and its object is to improve the efficiency and economy of steam turbines
by removing certain sources or causes of loss of effect which I have discovered can
be removed by steam or other hot jacketing or superheating.
In steam jacketing the cylinders of reciprocating steam engines, as commonly
practised, the main object is to prevent initial condensation and subsequent
re-evaporation, and it is commonly understood that the initial condensation is mainly
due to the oscillations of cylinder temperature brought about by the cooling action
of the expansion proceeding in the cylinder during the stroke. The cylinder and
cover surfaces thereby become cooled towards the temperature of the discharge
steam, and the entering high pressure steam at the beginning of a new stroke
becomes condensed to heat up the walls again. This condensed water re-evaporates
as the stroke proceeds, and so great loss is caused and further cooling of the cylinder
walls occurs.
In steam turbines where the steam is caused to flow through vents or blades and
acts by its momentum to cause the wheels to revolve, no cut-off is necessary to
The
secure the working of the machine and the expansive action of the steam.
temperature and pressure of the steam in contact with the parts of the engine
remains constant or approximately constant for long periods covering many
revolutions of the engine, and there is consequently no condensation and
re-evaporation of the kind that occurs in piston or reciprocating engines.
A little loss may occur by the conduction of heat from the hot part of the turbine
to the cooler part due to the metallic contact or continuity of the rings and case of
the turbine, but that loss is inconsiderable. I have, however, discovered that a
great and totally different loss of power occurs from the supersaturated condition
of the steam consequent upon the work done by it upon the blades in moving them
and driving the engine. This supersaturated condition in which a larger or smaller
proportion of water is condensed, has the effect of impeding the flow of steam
through the vents, blades and passages, and by the introduction of liquid instead of
gaseous friction between the fixed and moving parts, causes a serious retarding
influence on the turbine wheels, discs and rings of blades. The great loss of power
that this invention is intended to remove is not due to diminished volume of steam
caused by partial condensation of the active steam and subsequent re-evaporation,
but is that loss due to the liquid friction of water as described, which liquid friction
it is obvious when acting between fixed and moving surfaces is many times greater
than that of gaseous steam at ordinary pressures and temperatures.
Referring to the accompanying sheet of drawings, Figures 1, 2, 3, 4 and 5
illustrate the application of my invention.
My invention may be applied in various ways keeping in view that the main
object is to prevent the admission of liquid water to the turbine, or formation of
liquid water within the turbine ; may accomplish this object, for example, by
superheating the steam before admission in order that the temperature may be
sufficiently elevated for the steam to sustain the various losses of heat without
liquifaction, but this method would involve a temperature so high as to be detri-
mental to the surfaces of the engine, or it might cause distortion or damage, so
that I do not apply it except in special circumstances. When I do apply it I
arrange a superheater A (Figure 1) containing a coil or other tubular surface A¹
through which steam passes to the turbine B. The coil A¹ is heated to a suitable

page_text: temperature by hot gases passing through the casing A in the direction of the
arrows.
I prefer to steam jacket the engine in such a way as to supply the heat as
required to maintain the steam in a gaseous condition during its course, and prevent
condensation without great excess of temperature above the point of saturation,
and several methods of applying the jacketing are shown at Figures 2, 3, 4 and 5.
The jacket may be continuous, or it may be arranged in successive steam jackets
or heaters to dry and moderately superheat the steam, on its passage from one set
of turbines to the next, and a sufficient surface and number of heaters is provided
to prevent condensation.
By either the continuous or the discontinuous method, I prevent condensation
without the necessity of dangerously superheating the steam.
so
For these arrangements I may obviously use jacket steam drawn from the main
boiler or an auxiliary boiler at any or a higher pressure than the main boiler. I
may also jacket with heated liquids kept at a regulated temperature and suitably
heated and regulated.. I may likewise apply heated gas, the products of com-
bustion or gases from a flame of coal or other gas or solid. Sometimes too I may
use liquids and solids, such as caustic soda, acetate of soda or other substances
having considerable absorptive properties for heat, which on cooling continue to
give out heat at nearly constant temperature for long periods. In all cases,
however, whatever be the heating arrangements, I proportion the thickness of
metal and the absorbing surfaces and transmitting metal in such manner in relation
to the turbines as to provide the necessary transmission of heat to secure the object
of the invention. In applying my invention to radial flow steam turbines,
arrange the guide rings or casing containing the guide rings of blades that they
shall be more or less surrounded with high pressure steam by which they may be
heated, and so transmit heat through their substance and through and along the
blades to the working fluid. I may hollow, core or drill out cavities in the discs,
rings or case to contain the jacket steam and increase the effective surface exposed
to it. In all cases I supply the jackets with steam and drain off in the most
convenient way.
I sometimes arrange to jacket the rotating wheels or rings as well
as the stationary ones, by providing them with suitable hollows by coring, drilling
or other process to receive jacket steam, and in such a construction I introduce by
the jacket steam and drain off water of condensation by means of a hollow rotating
spindle.
In another construction of guide rings I form the rings to abut each other by
spigot and fawcet joint or by faced joint only, and build up a compound cylinder
which I hold together by longitudinal bolts, and so enclose the working discs or
rings of blades. This built up cylinder I enclose within a case containing high
pressure steam, from which steam the cylinder receives and transmits heat to the
working steam and moving discs or rings of blades within. The guide rings
forming the built up cylinder may be hollow drilled or cored out to increase the
effective heat absorbing surface and diminish the thickness of metal through which
heat is to be transmitted.
In this construction, each ring forming part of the cylinder may be cast hollow,
and each may be connected to the others and to the supply of jacket steam, and
so arranged as to drain into a common drain, or the rings may be cast solid and
brought into contact with an arrangement of pipes, containing jacket steam.
may simply jacket the rings externally and rely upon the conductivity of the
metal to carry the necessary heat to the working parts, but this arrangement I
prefer for small turbines where the lineal dimensions are not great.
In these constructions I may increase my heat absorbing surfaces in contact with
the jacket steam by casting or forming webs, ribs or grooves which prevent an
extended surface to the hot steam, and in the case of ribs or webs I may perforate
them to further increase the absorbing surface.
In parallel or approximately parallel flow steam turbines I adopt an equivalent
arrangement, such as casting the case hollow to contain jacket steam, the heat

page_text: being conveyed by conduction from the case to the rings of blades, or I adopt other
convenient methods such as I have herein before indicated.
In Figure 2 I show a part of a radial steam turbine in which the fixed rings C¹
are formed with spigot and fawcet joint and longitudinal bolts hold the whole
together. The rings are formed or cast hollow to leave annular spaces D, which
spaces communicate with each other and form a series of connected steam jackets.
The high pressure steam is passed through these spaces and suitable drainage
arrangements are provided.
In Figure 3 the rotating rings E of a steam turbine are shown as cored out for
jacketing, and the steam is supplied to the cored out cavities E', through a hollow
rotating spindle F; the spindle F being the turbine spindle.
In Figure 4 the arrangement is as in Figure 2, but the built up rings C' are
surrounded by an outer casing G, leaving a space G¹ through which steam may
also be passed.
In Figure 5 a parallel flow turbine is shown in which the casing H has a
chamber H' forming the jacket.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
(1) Jacketing a steam turbine in such manner that steam or other fluids at a
suitable temperature may be applied to keep the fixed and rotating surfaces hot,
substantially as herein before set forth.
(2) The combination of a superheater and steam turbine substantially as and
for the purposes hereinbefore set forth.
(3) The several arrangements of continuous and discontinuous jacketing
substantially as hereinbefore described and illustrated in the drawings annexed.
Dated this 20th day of January 1892. –
MARKS & CLERK,
13, Temple Street, Birmingham, Agents for the Applicant.