IMPROVEMENTS IN GENERATING AND CONDENSING STEAM AND IN FIRE-PLACES AND FURNACES
Year: 1850

page_text: SYMES PRIDEAUX, of Southampton, Gentleman, send.greeting.
WHEREAS Her present. most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Greyt
Britain and Ireland, bearing date at Westminster, the Twenty-eighth day of
December, One, thousand, eight hundred and fifty, in the fourteenth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Thomas Symes Prideaux, my exors, admors, and assigns, Her
especial licence, full power, sole privilege and authority, that I, the said
Thomas Symes Prideaux, my exors, admors, and assigns, or such others as
I, the said Thomas Symes Prideaux, my exors, admors, or assigns, should
at any time agree with, and no others, from time to time, and at all times
during the term of years therein expressed, should and lawfully might make,
use, exercise, and vend, within England, Wales, and the Town of Berwick
upon Tweed, my Invention of "IMPROVEMENTS IN GENERATING AND CONDENSING
STEAM AND IN FIRE-PLACES AND FURNACES;" in which said Letters Patent is con-
tained a proviso that I, the said Thomas Symes Prideaux, shall cause a par-
ticular- description of the nature of my said Invention, and in what manner
the same is to be performed, by an instrument in writing under my hand and
seal, to be inrolled in Her said Majesty's High Court of Chancery within six
calendar months.next.and immediately after the date of the said in part recited
Letters Patent, as in and by the same, reference being thereunto had, will more
fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Thomas Symes Prideaux, do hereby declare that the nature of my said Inven-
tion, and the manner in which the same is to be performed, are fully described
and ascertained in and by the following statement thereof, reference being had
to the Drawing hereunto annexed, and to the figures and letters marked
thereon, that is to say :-
I will proceed to explain the first part of my Invention. Figure 1 is a longi-
tudinal section of a steam boiler constructed according to my Invention; and
Figure 2 is a plan in section of the same. In each of these Figures the same
letters indicate similar parts; a is the furnace, and the grate bars con-
structed in the usual manner. The peculiarity of this furnace consists in, first,
a thin lining of fire brick c, extending from the fire bars on the one side over
the roof to the fire bars on the opposite side, and in close contact with the
under side of the boiler, by which arrangement not only is this portion of the
boiler preserved from those sudden alternations of temperature practice has
shown to be so injurious to its durability, but the uninflamed gases liberated
from the fuel have a much better chance of being inflamed than happens when
they are suddenly reduced in temperature by the contact of the iron boiler
bottom. Secondly, in order the more effectually to secure their combustion,
however, I insert one or more rows of water tubes, cased with fire brick, at the
flue bridge (where they are very advantageously placed for generating steam),
that thus the gases being intimately commingled and divided into small streams,
and then their temperature raised by contact with the red hot fire brick casing
of the tubes, their passing off by the flue unburnt may be impossible, supposing
the supply of air be sufficient. Thirdly, in some cases I deem it desirable to
extend the fire brick casing through a portion of the flue, see g, in the Drawing.
The other portions of the furnace require no comment, being constructed in the
ordinary manner; e is a water flue bridge; f, ascending main flue; fare
horizontal flue tubes; and f", the chimney; w, water space; and w, l, water
line; and s, steam chest.
Secondly, my Invention has for its object improvements in constructing
tubular boilers.
"
Figure 3 shows a transverse section; and Figure 4, a side section of a boiler;
constructed according to this part of my Invention. It consists of a series of
tubes. a, a, falling slightly from the fire to the back end; these tubes are heated
externally, and are to have covers f, f, at their ends, so as to give ready access
to the interior in order to cleanse the same; from these tubes rise several other
tubes b, b, of a conical form, so that the space between them as they rise from
the tubes a, a, decreases, such space between the tubes acting as a flue or heat

page_text: chamber for heating the tubes exteriorly, as will readily be understood on
examining the Drawing. The supply of water is to be into the lower part of
the tubes a, a, by the connecting tube c. The upper parts of the tubes 6 form
so many steam chambers, communicating freely with each other by apertures
at the level of the line d, and discharging their steam by the steam pipe e.
The tubes b, b, also communicate freely with each other by a second series of
apertures on a level with the line c, just below the water surface, and have, like
the tubes a, a, moveable covers g, g, at their ends for the convenience of ready
access for cleaning.
I would state that by this arrangement it will be evident that in case of such
boiler being used for marine steam engines, the water line will not be liable to
such injurious fluctuations as at present by the inclining of the ship or vessel.
In addition to which such boilers will not only be very strong, but they, will
offer a very great extent of heating surface for a given quantity of water.
I would remark that I am aware that various constructions of tubular boilers
have before been constructed, and the novelty consists in the mode of con-
structing the tubes a in combination with a series of rising or upright tubes,
larger at their upper ends than their lower ones.
The third part of my Invention consists of lining the steam chamber of
boilers with loosely woven hempen cloth or any porous or fibrous material
capable of absorbing water by capillary attraction. Steam boilers, as at present
constructed, may be said to consist of two parts, a steam generator and a steam
reservoir; and as in order to prevent the portion of the boiler above the water
line from becoming too hot, no flues are allowed to extend higher than within
nine or twelve inches below the surface of the water, nearly the upper half of
the boiler is withdrawn from the application of heat, and the products of com-
bustion still at a temperature capable of generating steam are carried off into
the chimney, instead of being allowed to ascend in contact with the boiler to
its summit. Notwithstanding, however, the precaution of placing the flues at
a certain distance below the water level, when an engine stops working for a
considerable time, and the surface of the water, no longer agitated by the alter-
nations in pressure consequent upon the opening and closing of its communi-
cation with the cylinder, remains quiescent under a steady pressure of steam, it
often happens that the sides of the boiler above the water level become unduly
heated, and the result is, that when the engine re-commences working and the
surface of the water becomes agitated in consequence, a sudden evolution of
steam and violent explosion takes place, too often attended with a frightful loss
of human life. In corroboration of this view of the case, it will be found that
the great majority of explosions occur, not whilst the engine is stopping, but.

page_text: just after it has recommenced working, and made one or two strokes. To
prevent these shocking catastrophes in the first place; to encrease the capacity
of a boiler of a given size for generating steam by making its upper as well as
its lower surface available for this object, in the second place; and to econo-
'mise fuel by causing the products of combustion to pass round the upper as
well as the lower portion of the boiler, in the third place; I propose to line
the inside of the steam chamber or any desired portion of its lower part with
loosely woven hempen cloth, or any porous or fibrous material capable of
absorbing water by capillary attraction; such lining to be kept in close appo-
sition with the inside of the boiler by a wire framework, or any other suitable
mode of fastening, whilst its lower edge must always extend to or below the
surface of the water, and in certain cases it may be desirable to make use of the
feed water to assist in keeping wet its upper part.
The fourth part of my Invention consists in the employment of a self-regu-
lating apparatus for heating the passage or passages by which the steam is
conveyed from the boiler to the cylinder, or for heating the cylinder itself,
.either alone or in conjunction with the steam pipe; but I prefer the application
of heat to both conjointly, the economy of fuel being greater when the steam
receives an addition of heat in its passage from the boiler to the cylinder;
whilst the application of heat to the cylinder itself both economises fuel and
diminishes the injurious inequalities of pressure consequent upon working
expansively.
I would state that I do not claim the application of heat to the steam pipe,
nor yet to the cylinder, nor yet to the two combined, such having been already
done; but what I claim is, the addition to any apparatus for these
purposes of
a contrivance, automatic in its action, by means of which the access of heat
shall be regulated according to the temperature already imparted, so as to be
diminished or altogether cut off, when its further increase would be dangerous
or undesirable, with unerring certainty, and without the necessity of super-
intendence.
This regulation may be effected in various ways; that which I prefer is as
follows subdivide a portion of the steam pipe into a number of small
channels, to increase the amount of surface for the absorption of heat, and con-
struct it of copper as being a vastly better conductor than iron. This portion
I then surround with a metallic casing, and connect it by a pipe leading from
the bottom with the flue of the furnace, and by a pipe leading from its top with
the chimney. The pipe leading from the furnace is furnished with a throttle
valve, which is acted upon and partially or wholly closed, either by the expan-
sion of mercury in a tube with a loosely fitting loaded piston, or by the expan-

page_text: sion of a bar of copper, or other suitable metal, connected at one end with a
lever, and acting after a manner which is well understood, such vessel of
mecury, or bar of copper or other metal, being placed in close contact with a
portion of the copper steam pipe, so as to be readily affected. by its temperature
and at the same time shielded from the direct action of the current of heated
gases coming from the furnace. The cylinder I propose to construct of gun
metal or bronze as being better conductors of heat than iron, and at the same
time possessing the requisite hardness. I further propose to construct the
outside of the cylinder with transverse ribs, both to facilitate the transmission
of heat, and as affording the requisite strength with a smaller amount of metal
than the present form. I effect the regulation of the supply of heat furnished
to the cylinder in the same method I have already described for the steam
pipe, viz, by surrounding it with a metal casing communicating with the fur-
nace by a pipe, the size of the aperture of which is governed by the temperature
of the cylinder, and having another pipe leading into the chimney. In certain
cases it may be found advantageous to convey the heated gases of the furnace
from the cylinder to the steam pipe, or vice versa, and then into the chimney,
thus making only, one direct communication with the furnace and one with the
chimney subserve the purpose of heating both vessels.
The fifth part of my Invention consists in the employment of a fan blast and
closed ash pit, for locomotives or other non-condensing engines, where a keen
draft and low chimney are desiderata in combination with the present steam
jet. In locomotives, as at present constructed, the eduction pipe is led into the
chimney, and the, draught through the furnace is produced by the force of the
issuing steam rushing through a contracted orifice, and at the expense of a
certain amount of resistance to the piston. This method has the advantages of
handiness and simplicity, and on this account, although a wasteful mode of
generating force, may be advantageously trusted to, where only the attainment
of a moderate velocity is required. Where, however, so intense a draught is
demanded as to necessitate the contraction of the mouth of the eduction pipe
to such an extent as to swallow up a large portion of the power of the engine,
instead of resorting to this expedient, I assist the effect of the blast pipe and
increase the draught by supplying the furnace with compressed air by means
of a fan, a much more economical mode of obtaining the power required than
by relying solely on a steam jet. I would state, that I do not claim the use
of a fan for forcing air to the furnaces of locomotive steam boilers when not
used in combination with a jet of steam, the novelty of this part of my Inven-
tion consisting of the combined use of these two agents.
The sixth part of my Invention.consists of improvements in the construction

page_text: of condensers when condensing without injection; for this purpose I construct
the condenser of thin corrugated sheets of copper, placed parallel to each
other at small intervals, the spaces being occupied alternately by steam and
water, and the water I cause to flow rapidly through the water spaces by
means of a centrifugal pump, or a head of water where such can be con-
veniently obtained.
The seventh part of my Invention consists of improvements in fire-places
by making the lower bar moveable so as to allow of the fuel at the bottom
being raised by a suitably shaped shovel, and the fresh charge of fuel inserted
beneath it, and also in employing reflectors with horizontal ribs, the angle of
inclination of which increases as they recede from the fire. Figure 5 shews
a vertical section of a fire-place with jamb of the old construction, exhibiting
the erroneous direction in which the rays of heat are reflected by it. Figure 6
shews a vertical section of a fire-place with the improved jamb, contrasting
the direction in which the heat is reflected by it with that shewn in Fig. 5.
Figure 7 shews a front view of the improved grate; the middle third of the
first bar from the bottom of the grate at a is made to open on a hinge; see
the bar drawn in its position when open, in red ink. To supply fresh fuel to
the fire, this bar is opened and a flat shovel introduced and passed along the
bottom till it reaches the back; by depressing its handle the edge is caused
to slide up the back of the grate, till it slips up on a narrow ledge b,
made for the purpose, on a level with or slightly below the second bar of the
grate; the handle is now raised till the front of the shovel comes in contact
with the second bar, to which it is suspended by two crooks c, in the same
way as a Dutch oven. The body of fuel occupying the middle third. of the
fire below the second bar having been raised by this operation, a vacant space
is left beneath the shovel, to be supplied with coals by a scoop in the ordinary
The shovel is then gently slipped out and the bar closed. Figure 5
shews a vertical section of the fire-place and jambs, with the angle of reflection
according to the old mode of construction, by which it will be seen, that it is
only the rays of heat which strike the lower portion of the jamb which are
reflected into the room and made available to the purpose of heating it; as
they impinge above this, they are progressively reflected more and m
upwards, first towards the ceiling and then up the chimney, instead of hori
zontally outwards into the apartment, as will be manifest from the diagram,
Figure 5. To obviate this great loss of heat I propose to construct the jambs
of a series of reflecting surfaces, arranged in horizontal strips d, somewhat
resembling Venetian blinds, the inclination of each increasing slightly from
below upward in such a ratio that each shall reflect a ray of heat proceeding
manner.

page_text: from the centre of the fire horizontally outwards into the apartment, as is
indicated at Figure 6. These reflectors may be made either of polished brass
or steel, and if of the latter, may be advantageously set in zinc, that so being
rendered negative, oxydation or rust may be prevented, and their brightness
preserved.
The eighth part of my Invention consists of the employment of a self-
closing valve for admitting air above the grate bars in reverberatory furnaces
and steam boiler furnaces. It is a well-known fact, that to attain perfect
combustion with its attendant economy of fuel and absence of smoke, the
supply of air to a furnace should be apportioned to the quantity, quality, and
state of the fuel undergoing combustion, and many are the attempts that have
been made to realise this desideratum. Hitherto, however, if we may judge
from the limited adoption of the methods introduced, the object has only been
effected by the use of machinery so costly or inconvenient in itself as to coun-
terbalance the advantages in economy of fuel to be secured by its adoption.
The object may be attained in two ways, either by making the supply of fuel
regular and continuous, or by encreasing the supply of air at the periods of
coaling, and gradually diminishing it as the gasifaction of the more bituminous
portion of the fuel proceeds. The former would appear theoretically to be the
most perfect method; and Brunton's revolving grate, Jucke's endless chain of
fire bars, and Stanley's rotary feeder act on this principle. All, however,
seem to be more or less open to the objection before stated; and what is certain,
is, that furnaces at present are almost universally worked on the system of the
coals being supplied at intervals by hand (which may therefore be assumed to
be found in practice the easiest method), and without any provision for varying
the supply of air in accordance with the wants of the fire.
Adapting, therefore, my ideas to the mode of firing in ordinary use, and
which I believe to be in the majority of cases the most feasible, I act on the
principle of adjusting the supply of air to the wants of the fuel by means of
a self-closing valve opening into the furnace above the fire-grate bars, which
valve being set wide open at each period of firing, shall gradually close of its
own accord without requiring any superintendence, thus furnishing a gradually
diminishing supply of air as the more bituminous portions of the fuel become
gasified till it finally closes.
The size of the aperture of the valve and the time occupied in closing, is
to be adjusted in accordance with the quantity of fresh fuel usually supplied
at one time, together with the quality of this fuel and the nature of the
furnace, and the admission of air is to be sufficient to prevent the appearance
of smoke at any period.

page_text: The self-closing motion may be imparted to the valve by any convenient
mechanical contrivance; that which I prefer is a weight affixed to the end of
a lever, the other end of which is attached to the spindle of the valve.
The weighted end of the lever being raised by the fireman immediately
upon closing the door after firing, will, in descending through the segment of
one-fourth of a circle, by its own gravity close the valve, whilst a gradual
motion. is given to its descent by connecting the spindle of the valve with a
train of wheelwork giving motion to a fly or vaned wheel.
By attaching the weight to the end of the lever by a screw, so that. its
distance from the centre may be varied at pleasure, the period occupied by
the closing of the valve may be regulated with great nicety, or the same
object may be affected by making the vanes of the fly wheel moveable, so that
they may be made to offer a larger or smaller surface for resistance to the air.
The ninth part of my Invention consists of the application of water in the
ash-pit of reverberatory furnaces and steam boilers in combination with closed
ash-pits, and the use of air under pressure.
I do not make this proposition under the erroneous idea so often entertained,
that the total quantity of heat to be obtained from fuel is encreased by the
employment of water, because. I am aware that an amount of heat equal to
that given out by the combustion of the hydrogen of the water must have
been previously taken from the ignited carbon to effect the decomposition of
the water.
The benefit I propose to obtain is, that I borrow the heat from the lower
portion of the fuel in the grate where it produces the disadvantage of unduly
heating the ash-pit and inconveniencing the workmen, and transfer it to the
body of the furnace where it is required; thus increasing the body of flame
in the furnace at the expence of diminishing the intensity of the glow fire in
the bottom part of the grate.
Another advantage attending the use of water is, that it prevents the igni-
tion of the ashes that fall through the grate bars.
Having thus described the nature of my said Invention and in what
manner the same is to be performed, I would have it understood that what
I claim, is,
First, the coating the inside of the furnace of steam boilers and any desired
portion of the flues with fire brick (or any stone or composition having analo-
gous qualities), and the placing one or more rows of water tubes cased outside
with fire-brick (or any equivalent substitute) at or behind the flue bridge, and
I claim also the use of a closed ash-pit and air under pressure in combination
with the above form of furnace.

page_text: Secondly, I claim the mode of constructing tubular boilers herein described.
Thirdly, I claim the applying a lining of porous or fibrous matters to the
interior of the steam chamber of steam boilers.
Fourthly, I claim the addition to any apparatus for heating the steam in its
passage from the boiler to the cylinder, or for heating the cylinder of a con-
trivance for automatically regulating the heat applied according to the tempe-
rature produced.
Fifthly, I claim the combined use of a fan blast with a steam jet for the
furnaces of locomotives and other non-condensing engines.
Sixthly, I claim the mode herein described of constructing condensers of
steam engines by employing corrugated metal arranged to produce parallel spaces.
Seventhly, I claim the constructing fire-places with bars to open as herein
explained, and I also claim the mode of applying reflecting surfaces herein
described.
Eighthly, I claim the application of valves to be closed by suitable apparatus
at a determined time after supplying the fire with coal.
Ninthly, I claim the combined use in the ash-pits of reverberatory and
steam boiler, furnaces of water and air under pressure in closed ash-pits.
In witness whereof, I, the said Thomas Symes Prideaux, have hereunto
set my hand and seal, this Twenty-eighth day of June, in the year of
our Lord One thousand eight hundred and fifty-one.