Year: 1896

page_text: Date of Application, 10th Apr., 1896
Complete Specification Left, 5th Jan., 1897-Accepted, 27th Mar., 1897
I, WILLIAM ISAAC LAST, of 3 Balmuir Terrace, Putney, in the County of
London, do hereby declare the nature of this invention to be as follows:-
My invention has for its object to prevent the condensation in steam engine
cylinders due to what is known as "cylinder wall action," by maintaining all
internal exposed surfaces at at least as high a temperature as that of the entering
steam.
According to my present invention, I effect this by passing through chambers
jackets or channels immediately behind or imbedded in the metal of the said
surfaces, steam superheated to such a degree that notwithstanding the cooling
action to which it is subjected in the said chambers &c. it shall still be in a super-
heated condition as it leaves them, thereby withdrawing from the jackets the
heating steam so soon as its temperature has fallen to or nearly to the still high
temperature at which it is necessary to maintain the metal behind the said steam
exposed surfaces, and below which temperature if the jacket steam is allowed to
remain, the transfer of heat from the jacket steam to the cylinder metal will not
suffice to maintain the said steam exposed surfaces at the required temperature to
prevent the losses due to cylinder wall action.
The somewhat cooled superheated steam, on issuing from the chamber &c.,
I then, by a pump, fan, or injector, return to superheating coils or similar appliance
placed in a furnace, to be reheated and be again sent through the jackets, and so
on. Or I may send the cooled superheated steam from the jackets into the steam
chest and cylinder of the engine, where it can be utilised to give off work in the
usual manner.
Owing to the very high temperature that I find to be necessary in the jackets
of steam engines to maintain such hot walls it is usually inconvenient to have in
the jackets saturated steam of the requisite temperature, on account of its high
pressure; by employing superheated steam in the manner above described the
advantage is gained of obtaining the requisite high temperature without sub-
jecting the cylinder to the undue strain caused by such high pressure saturated
steam.
It will be generally most convenient and economical to deliver the still super-
heated steam from the jackets into the steam chest of the engine and to use it
alone, or together with other steam, which need not itself necessarily be superheated,
to drive the piston.
Where the jacket steam is derived from the same boiler as the main steam, and
the latter is not sufficiently superheated for the jacketing, a superheater may be
fitted in the furnace or flue or uptake of the boiler, and through it be passed the
steam to supply the jackets.
To secure that the desired quantity of steam shall flow through the jacket
circuit, a valve or other throttling resistance may be placed in the inain or direct
steam course to the steam chest, s. as to equalise the otherwise unequal circuits
between the steam space of the boiler and the engine steam chest.
The quantity of steam required through the jackets will usually be very much
less than the total quantity used by the engine, so that the dimensions of the jacket.
superheater will only be small for many engines. I may attain the desired How

page_text: through the jackets by supplying their superheated steam from a separate boiler at
a higher pressure than the main steam supply.
To facilitate the transfer of heat from the superheated jacketed steam to the
metal of the jackets I may increase the metal surface within the jacketing chambers
by forming it with ribs, gills, pegs or similar projections, or I may pack it with
metal wire, bails &c., in this way reducing the excess temperature necessary to
force the said transfer of heat at the desired rapidity.
For compound or higher successive expansion engines I may jacket with super-
heated steam of a lower pressure than the high pressure boiler steam and then
when it is cooled so far as I consider is advisable for jacketing steam I pass it into
the steam chest of a lower pressure cylinder, letting it then work through the
remaining cylinders as working steam.
The object of this. arrangement is to avoid putting the highest pressure steam
into the large jackets of the lower pressure cylinders, which they may not be
sufficiently strong to resist.
In successive expansion engines I find that after the high pressure cylinder the
other cylinders may be jacketed suitably by saturated steam in the following way.
For the second cylinder I fill its jackets from the steam chest of the first, for
the third cylinder I supply its jackets from the steam chest of the second, and so
on, but all of the jackets must be suitably drained, and the drainage may be
successive. The high pressure cylinder, however, requires the superheated
jacketing and the removal of its jacketing steam while still superheated, as before
described.
The term "jacket" is to be understood to include also the chambers &c. forined
in cylinder covers and pistons for heating purposes.
Dated this 10th day of April 1896.
ABEL & IMRAY,
Agents for the Applicant.
1, WILLIAM ISAAC LAST, of No. 3 Balmuir Terrace, Putney, 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 has for its object to prevent the condensation in steam engine
cylinders due to what is known as "cylinder wall action" by maintaining all
internal steam exposed surfaces at at least so high a temperature as the saturation
temperature of the entering steam.
To maintain the surfaces at this temperature it is necessary in order to counteract
the chilling action of the exhaust stroke that the metal behind these surfaces shall
be at a much higher temperature than that corresponding with steam at the boiler
pressure.
According to my present inventicn I effect this by passing through chambers,
jackets or channels immediately behind or imbedded in the metal of the said
surfaces, steam superheated to such a degree that notwithstanding the cooling
action to which it is subjected in the said chambers &c., it shall still be in a super-
heated condition when it leaves them. I therefore withdraw from the jackets the
heating steam so soon as its temperature has fallen to, or nearly to, the still high
temperature at which it is necessary to maintain the metal behind the said steam

page_text: exposed surfaces, and below which temperature if the jacket steam is allowed to
remain, the transfer of heat from the jacket steam to the cylinder metal will not
suffice to maintain the said steam exposed surfaces at the required temperature to
prevent the losses due to cylinder wall action.
The somewhat cooled superheated steam on issuing from the chambers &c.,
I then by a pump, fan, or injector, return to superheating coils or similar appliance
placed in a furnace, to be re-heated and be again sent through the jackets, and
so on. Or I may send the cooled superheated steain from the jackets into the
steam chest and cylinder of the engine, where it can be utilised to do work by:
driving-a piston in the usual manner.
Owing to the very high temperature that I find to be necessary in the jackets of
steam engines to maintain such hot wall, it is usually inconvenient to have in the
jackets saturated steam of the requisite temperature, on account of its high
pressure; by employing superheated steain in the manner above described the
advantage is gained of obtaining the requisite high temperature without subjecting
the cylinder &c., to the heavy strains caused by such high pressure saturated
steam.
It will be generally most convenient and economical to deliver the still super-
heated steam from the jackets into the steam chest of the engine, and to use it
alone or together with other steam which need not itself necessarily be superheated,
to drive the piston.
Where the jacket steam is derived from the same boiler as the main steam, and
the latter is not sufficiently superheated for this jacketing, a superheater may be
fitted in the furnace or flue or uptake of the boiler, and through it be passed the
steam to supply the jackets.
To secure that the desired quantity of steam shall flow through the jacket
circuit, a valve or other throttling resistance may be placed in the main or direct
steam course to the steam chest, so as to equalise the otherwise unequal circuits.
between the steam space of the boiler and the engine steam chest; or the steam
from the jacket may be utilised in driving an engine or cylinder of lower
pressure.
The quantity of steam required through the jackets will usually be very much
less than the total quantity used by the engine, so that the dimensions of the jacket
superheater will only be small for many engines.
1 may attain the desired flow through the jackets by supplying their super-
heated steam from a separate boiler at a higher pressure than the main steam
supply.
To facilitate the transfer of heat from the superheated jacketing steam to the
metal of the jackets, I may increase the metal surface within the jacketing
chambers by forming it with ribs, gills, pegs, or similar projections, or I may pack
it with metal wire, balls &c., in this way reducing the excess temperature necessary
to force the said transfer of heat at the desired rapidity.
For compound or higher successive expansion engines I may jacket with super-
heated steam of a lower pressure than the high pressure boiler steam, and then
when it is cooled so far as I consider is advisable for jacketing steam, I pass it
into the steam chest of a lower pressure cylinder, letting it then work through the
remaining cylinders as working steam. The object of this arrangement is to avoid
putting the highest pressure steam into the large jackets of the lower pressure
cylinders, which they may not be sufficiently strong to resist.
In successive expansion engines I find that after the high pressure cylinder,
the other cylinders may be jacketed suitably by saturated steam in the following
way. For the second cylinder I fill its jackets from the steam chest of the first,
for the third cylinder I supply its jackets from the steam chest of the second and
so on the steam from the jackets of the second, third &c. cylinders being made to
pass respectively into the steam chest of the same cylinder.
All of the jackets must be suitably drained and the drainage may be
successive.

page_text: The discharge of steam from each jacket into its corresponding steam chest may
be controlled by. a valve to maintain the higher pressure in the jacket and to
regulate the amount of steam passing.
The high pressure cylinder, however requires the superheated jacketing and
the removal of its jacketing steam while still superheated as before described.
The term jacket is to be understood to include also the chambers &c. formed in
cylinder covers and pistons for heating purposes; when jacketing a piston the
steam discharged from it may be delivered into the cylinder instead of into the
steam chest for utilisation-by-an-arrangement shewn in my Specification No. 22296
⚫of 1895.
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In a steam engine in which the cylinder, cylinder covers and piston are
jacketed with superheated steam, withdrawing such steam from the jackets
before it has cooled to its saturation point, substantially as and for the purpose
.described.
2. In a steam engine jacketed with superheated steam, causing such steam to
ipass from the jackets into a working cylinder while still in a somewhat superheated
condition, substantially as described.
3. In a steam engine jacketed with superheated steam, withdrawing such steam
from the jackets while still somewhat superheated, and passing it through a
superheater in which it is reheated to its original temperature so as to be again
available for being passed through the jackets substantially as described.
4. In compound or multiple expansion steam engines supplying steam from the
steam chest of the first cylinder to the jackets of the second cylinder, from the
steam chest of the second cylinder to the jackets of the third cylinder, and so on,
the steam being made to pass from the steam jackets of the second, third &c.
cylinders respectively into the steam chest of the same cylinder, substantially as
.described.
Dated this 5th day of January 1897.
ABEL & IMRAY,
Agents for the Applicant.