IMPROVEMENTS IN APPARATUS FOR INCREASING THE DRAFT IN THE CHIM- NEYS OF STEAM SHIPS AND IN OTHER CHIMNEYS OR FUNNELS
Year: 1878

page_text: LETTERS PATENT to John Clayton Mewburn, of 169, Fleet Street, in the City
of London, Patent Agent and Consulting Engineer, for the Invention of
"IMPROVEMENTS IN APPARATUS FOR INCREASING THE DRAFT IN THE CHIM-
NEYS OF STEAM SHIPS AND IN OTHER CHIMNEYS OR FUNNELS." A com-
munication from abroad by Alexander Friedmann, of Vienna, Austria, Engineer.
Sealed the 31st January 1879, and dated the 16th November 1878.
PROVISIONAL SPECIFICATION left by the said John Clayton Mewburn
at the Office of the Commissioners of Patents on the 16th November 1878.
JOHN CLAYTON MEWBURN, of 169, Fleet Street, in the City of London, Patent
Agent and Consulting Engineer. "IMPROVEMENTS IN APPARATUS FOR INCREASING
THE DRAFT IN THE CHIMNEYS OF STEAM SHIPS AND IN OTHER CHIMNEYS, OR
FUNNELS." [A communication from abroad by Alexander Friedmann, of Vienna,
Austria, Engineer.]
The production of steam in steam ships is essentially dependent upon the draft
of the chimney of the steam boilers. On the 29th January 1874, Letters Patent,.
No. 373, were granted to my present correspondent Alexander Friedmann, in the
Specification of which he described the fitting and use in the chimneys of steam-
ships of a compressed air blast apparatus to assist or increase the draft.
The principle of assisting the draft of chimneys of steam boilers of steam ships
by means of compressed air has therefore already been made known by him, and
he also described in the aforesaid Specification a special apparatus for carrying out
this principle. Now the present Invention consists of improved apparatus for
carrying out the principle, that is to say, of assisting the draft in the chimneys of
steam ships by an air blast apparatus. In fact, it has been fonnd that the air
blast apparatus described in the aforesaid Specification is a great obstruction when-
ever the chimney works solely with its natural draft.

page_text: According to the present Invention, the compressed air is made to escape around
the whole inner circumference of the chimney, the gases near the inner surface of
the chimney being specially slow in ascending. For this purpose there is formed
in the chimney of the steam boilers of steam ships, and around the inner circum-
ference of the said chimney, an annular orifice through which compressed air from
a fan or other blowing apparatus enters the chimney, so that the said compressed
air sweeps the inner circumference of the part of the chimney situated above the
annular orifice, and drives or draws up first the combustion gases which are in
stagnation against and near the inner surface of the chimney, and gives an impulse
also to the rest of the ascending gases, thus increasing the velocity of ascension of
the whole of the combustion gases, and therefore also the draft of the chimney.
Further, the inner surface of the chimney beginning at the place where the
compressed air enters is made slightly converging for a moderate distance, so that
the inner diameter of the chimney becomes gradually smaller. From the point
where the inner diameter of this part of the chimney is the smallest, the chimney is
for a short distance cylindrical, and then begins to diverge until it becomes again of
the ordinary diameter. Thus the whole chimney is as it were transformed into a
very large vacuum ejector similar to the ejector of Smith's vacuum brake, with the
difference that the driving medium, instead of being steam, is compressed air
entering a very large annular nozzle and that the inner diameter of the said nozzle
is formed by the surface of the chimney below the annular orifice, and the outer
diameter of the annular nozzle by the inner surface of the chimney above the air
inlet. This annular air inlet or air nozzle can be arranged near the upper edge of
the chimney, and then the apparatus is essentially a lifting or sucking apparatus,
rarefying the gases of nearly the whole volume of the chimney, and thus utilizing
nearly all the natural ascending force of the gases (due to their being hot, and
therefore specifically lighter than the air). This situation of the annular air nozzle
will be preferable, especially in commercial or passenger steamers.
For war steamers however, it may be preferred to arrange the apparatus at a
lower part of the chimney, so as to prevent its being destroyed during an engage-
ment, and to enable it to be utilized as a reserve in case the part of the chimney
above the deck gets damaged. The best height however to place the apparatus is
such that the end of the diverging part of the chimney above the annular air nozzle
shall coincide with the upper edge of the chimney.
As the apparatus is intended to increase the natural draft of the chimney, it is
evident that it will often be employed only as a reserve, and then it is important to
protect the annular orifice from being obstructed or incrusted while not in use by
the deposits of the smoke. For this purpose, the apparatus is arranged so that
either the converging part of the chimney which forms the outer diameter of the
annular nozzle of the air inlet, or that part of the chimney which forms the inner
diameter of the annular nozzle of the air inlet is movable, and thereby capable of
closing the annular orifice. This may be effected either by lowering the part abovė,
or by raising the part beneath the annular orifice. The cleansing of the apparatus
may be provided for in the same way.
Although I have herein-before spoken of compressed air for actuating the im-
proved apparatus steam can be employed, and although I have herein-before spoken
only of increasing the draft in the chimneys of steam ships, the apparatus can also
be applied to other chimneys or funnels, and especially to those of locomotive and
traction engines, in which case it may be actuated by the exhaust steam.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Clayton Mewburn in the Great Seal Patent Office on the 1st
February 1879.
JOHN CLAYTON MEWBURN, of 169, Fleet Street, in the City of London, Patent
Agent, and Consulting Engineer. "IMPROVEMENTS IN APPARATUS FOR INCREASING
THE DRAFT IN THE CHIMNEYS OF STEAM SHIPS AND IN OTHER CHIMNEYS OR
FUNNELS." (A communication from abroad by Alexander Friedmann, of Vienna,
Austria, Engineer.)
The Invention has for its object improvements in blast pipes or apparatus for
increasing the draft of chimneys by means of compressed air or exhaust steam from
engine cylinders.
The blast pipes hitherto used for this purpose were arranged in the centre of the
chimney or funnel. This construction had several disadvantages, as,
Firstly. There was only a small surface of contact between the blast and the
products of combustion.
Secondly. The gases passing along the inner surface of the chimney, and requiring
the most propulsion on account of their friction against the surface of the chimney,
received the least acceleration.
Thirdly. The exact central arrangement of the blast pipe was very difficult to
obtain and to retain.
Fourthly. Its presence in the middle of the chimney formed a great obstruction
to the ascension of the gases, or to the natural draft.
And, finally and chiefly. The propelling medium or blast which, on account of
its greater speed, is the most liable to form eddies, and thereby to loose a great
part of its useful effect if it is not continuously guided was, after having left the
orifice of the blast pipe, not guided at all. Now, according to the present Inven-
tion, all these disadvantages are avoided. In this present apparatus the compressed
air or exhaust steam from engine cylinders enters the chimney by an annular
orifice of nearly the same diameter as the chimney, formed all round the inner
circumference of the chimney, and being continually guided and confined therein
by conical surfaces, so that the whole chimney is transformed into a very large
vacuum ejector, similar to the ejector of Smith's vacuum brake, and that the
compressed air or exhaust steam forms a hollow cone of air or steam, the exterior
of which is continually guided and protected against forming eddies, while all the
combustion gases enter the hollow of this cone of air or steam, and are carried with
it into the atmosphere.
The blast may be as has been stated in the form of compressed air or exhaust
steam. The compressed air may be produced by any well-known kind of fan or
blower or ejector, and is by preference to be used in the arrangement for steam
ships. The exhaust steam is by preference to be used in locomotives or portable
engines, or such steam ships or engines which have not a condenser, and in which
the steam after having done its work in the cylinders, escapes into the atmosphere.
The accompanying Drawings show different constructions of blast pipes according
to this Invention.
In all the Figures, the same letters indicate corresponding parts.
In Figure 1, which represents in vertical section the improved apparatus as
applied to the chimney of a large steam ship, k, k, indicate a chimney constructed
of sheet iron as usual; it is provided with a reservoir b, b, into which moderately
compressed air is conducted by the pipe a. From the reservoir b, b, the air passes
through openings c, c, in the chimney into the space d, d, formed by the inner
surface of the chimney, and the outer surface of the slightly conical body e, e,
which is at its upper part of rather smaller diameter than the chimney, and at its
lower part joins the chimney. This body e, e, which I will call the suction cone,

page_text: enters another cone m, m, formed so that its upper diameter is rather less than
that of the chimney, while at its lower part it joins the chimney. I call this body
m, m, the collecting cone. In this manner an annular orifice of nearly the same
diameter as the chimney is formed, by which the compressed air will issue with
great speed, forming a hollow cone which is guided and confined at its exterior by
the inner surface of the collecting cone m, m. Thus, all the products of combustion
being below the level of the annular orifice, and especially also those subjected to
the friction of the inner surface of the chimney, will pass by the suction cone into
the hollow of the cone of the propelling air contained in the collecting cone m, m..
To the upper part of the collecting cone m, m, is joined a diverging cone n, n,
which at its upper part joins the chimney again, and which serves as a guide to the
air, until it becomes entirely mixed with the gases of the middle of the chimney,
and issues therewith into the atmosphere. In order to be able to regulate the
quantity of air, and to prevent the annular orifice becoming choked by soot when
the blowing apparatus is stopped, this orifice can be diminished or entirely closed
by lowering the collecting cone m, m, which is movable. The same result can be
obtained by having the collecting cone m, m, fixed, and making the suction cone e, e,
movable, that is to say, capable of being raised or lowered, an arrangement which
will be seen further on when I describe the application of the Invention to loco-
motives. For steam ships, however, it is better to have the collecting cone movable.
This can be effected in various ways, one of which is shewn in Figure 1, the
movement of the collecting cone being produced by four screws r, r.
The blast apparatus should be arranged as near the top of the chimney as
possible in order that the natural draft of the chimney may not be lost. It may,
however, be placed at the lower part of the chimney or directly over the boilers;
and in war vessels two apparatus, the one near the top, the other below the chimney,
may be placed, so that if the upper part of the chimney should be carried away the
lower apparatus could be put in action and act as a reserve.
Figure 2 is a simplification of Figure 1 in the sense that all its parts are immov-
able; still Figure 2 represents a complete apparatus, realising all the principles of
this Invention.
Figure 3 is a cheaper arrangement, but much less advantageous than Figure 2;
as in Figure 3 the diverging cone m, n, the useful functions of which have been
described, is omitted.
Lastly. Figure 4 represents an arrangement still cheaper than that of Figure 3,
but which is a restriction of one of the most important principles of the other
apparatus, and which therefore is much worse, because not only the diverging cone
but also the collecting cone m are omitted.
Comparing therefore the four arrangements shewn in Figures 1, 2, 3, and 4,
Figure 3 is an improvement on Figure 4, Figure 2 an improvement on Figure 3,
and Figure 1 an improvement on Figure 2.
The pipe for the compressed air for each of the four arrangements is arranged
either telescopically, as in Figure 3, for telescopic chimneys, or hinged, as in
Figures 4 and 4a, for hinged chimneys. In Figure 3 the air pipe is composed of
two parts, an upper movable part a, u, connected by a stuffing box to the lower
fixed part 8, 8, so that on lowering the upper chimney k, k, the pipe a enters the
pipe s. In Figures 4 and 4ª the air pipe a is curved horizontally in the line of the
axis of the hinge of the chimney, and enters by a horizontal stuffing box t the
lower air pipes, so that by lowering the upper chimney k on its hinge the pipe a
follows the movement. These two arrangements of the air pipe, whether that
shewn in Figure 3 or that shewn in Figures 4 and 4ª, represent an important part
of the chimney blast apparatus, since without it it would be impossible, at least in
movable chimneys of steam ships (and most steam ships' chimneys are movable), to
place the blast apparatus near the top of the chimney, a very important position to
allow the natural draft of the chimney to be utilized.
It has been stated that in all the arrangements shewn in Figures 1 to 4 the

page_text: apparatus works with compressed air, and for this purpose it is best to compress
the air by good fans or blowers, which draw air from the cabins and thus at the
same time establish a good ventilation of the interior of the ship.
For steam ships which have not a condenser, and in which the steam, after having
done its work in the engine cylinders, escapes into the atmosphere, instead of
compressed air it would be the exhaust steam from the cylinders which would be
conducted by the pipe a, a, into the chimney blast apparatus.
The importance of the apparatus is much increased if it be applied to loco-
motives.
Figures 5, 6, and 7 represent special constructions of the apparatus for loco-
motives. The steam escape apparatus or blast pipes of locomotives are still nearly
the same as in the first locomotive of Stephenson, and have the same defects. The
line of contact between the steam escaping from the pipe and the chimney gases
is
very very limited; the concentricity of the jet of steam with the axis of the
chimney, a concentricity which is so important is very difficult to establish and still
more difficult to maintain, and the exhaust steam on leaving the pipe is not in the
least guided and eddies much to the detriment of its useful effect.
It has been attempted to increase the line of contact between the steam and the
chimney gases by placing an annular pipe in the axis of the chimney, so as to
obtain a hollow jet, but the effect has been bad because the steam when it once left
the pipe was no longer guided and it eddied still more than with the old construc-
tion. And when, lastly, it was tried to interpose intermediate pipes between the
escape pipe and the chimney, they presented the inconveniences that they hid many
of the tubes in the smoke box, that they became quickly covered with soot, and
increased the friction of the gases, and lastly, they rendered the lighting more
difficult. The present improved chimney blast apparatus not only avoids in
locomotives all these inconveniences, but also produces very notable constructive
advantages.
b
In Figure 5 a, a, are the pipes by which the exhaust steam from the cylinders of
the locomotive enters the space b formed around the suction cone e, e, through which
cone all the gases from the smoke box ascend with much facility. From the space
the exhaust steam issues by the annular orifice formed around the suction cone by
means of the collecting cone m, m, and enters the said collecting cone, being
continuously guided and confined by the latter, thus forming a hollow cone of steam,
into the hollow of which all the combustion gases are conducted, and by which
they are afterwards lifted through the diverging cone n, n, which continues to act
as a guide to that part of the steam which in its passage through m, m, does not
become mixed with the combustion gases. The eddies of the exhaust steam are.
therefore reduced to a minimum, and the useful effect should therefore be much
greater, and is further increased by the following facts, viz.:-The line of contact
between the exhaust steam and the gases is very great, since it is almost equal to
the inner circumference of the chimney the concentricity of all the parts is
invariably exact; the delay which the combustion gases experienced in their passage
in contact with the inner surface of the chimney is eliminated since the steam
sweeps this surface very energetically; the sparks of the combustion gases are by
their entering the hollow cone of steam suffocated by the steam, and are thus less
liable to cause fire when leaving the chimney; and lastly, the smoke box, as well as
the middle of the chimney, are deprived of all parts liable to cause obstruction. To
this must be added the great simplification of construction, especially for new
locomotives, since the pipes for conducting the exhaust steam need not be carried
from the outside of the smoke box into the inside thereof, but will simply
pass from the cylinders around the smoke box to the ordinary joints of the
reservoir b, b.
In Figure 5 all the cones are fixed and immovable, that is to say, the escape is
fixed. The escape may be made variable by making the collecting cone m, m, or
the suction cone e, e, movable.
..In Figure 6 the variation of the escape is effected in a particularly good manner.

page_text: The suction cone e, e, is surrounded by a second cone v, v, movable on the first.
When this second cone v is caused to rise or to lower it will narrow or enlarge
the escape apertures, and all the joints remain nevertheless fixed and steam-tight.
This second cone v instead of being arranged around the suction cone as in Figure 6
can be inside the suction cone.
For new locomotives or where there is no inconvenience in making a new
chimney the cones m and n, or at least the cone n may be cast with the chimney.
Figure Ga is a horizontal section of Figure 6, and illustrates the use of an injector
u for producing the blast while the locomotive is standing. A jet of steam passing
through the tuyere draws with it sufficient air to create the required blast.
Figure 7 is a modification of Figure 5 which is especially recommended for those
locomotives in which the exhaust steam pipe is in the middle of the smoke box,
or in which it would be found inconvenient to remove the usual socket of the
chimney.
.
Figures 8 and 9 shew arrangements which are not so good in effect, but which
still are a great improvement on the ordinary escape apparatus of ordinary loco-
motives. In fact these arrangements, Figures 8 and 9, are a combination of the
improved chimney blast apparatus with the intermediate pipes of the old chimney
blast apparatus referred to in the earlier part of this Specification.
"In Figure 8 p represents the ordinary old socket of the chimney, in the axis of
which is placed the body of particular form, composed of two cones m and e.
These two cones together form an annular orifice of almost as large a diameter as
that of the chimney, and by which the steam from the cylinders escapes.
The cone
m is the collecting cone which acts as a guide to the steam after having left the
annular orifice, and the cone e represents the suction cone, by which the greater
part of the combustion gases from the smoke box enter the hollow cone of steam
contained in the collecting cone m, and mix therein with the said steam, and escape
with it into the locomotive chimney. On the entrance of the mixture of steam and
combustion gases from the collecting cone m, which in Figure 8 forms an inter-
mediate chimney into the chimney of the locomotive, a fresh quantity of combustion
gases, which rise between the outer surface of m and the inner surface of p are
added to the mixture, and are carried into the open air. The cones m and e there-
fore together represent a chimney blast apparatus analagous to the chimney blast
apparatus of Figure 7, with the difference that the collecting cone m is transformed
into an intermediate chimney, with respect to the chimney of the locomotive.
But in the apparatus, Figure 8, the inconvenience of the pipes or intermediate
chimneys of which I have herein-before spoken are almost entirely avoided, and
as at the same time the exhaust steam from the cylinders will act in the inter-
mediate chimney of the apparatus, Figure 8, with a useful effect much greater
than in the old arrangements therefor, the apparatus, Figure 8, although inferior
to the apparatus, Figure 7 or Figure 5, is still a great improvement.
In Figure 9 it is the suction cone which is transformed into an intermediate
pipe. In this Figure the annular orifice has a diameter almost as large as that of
the chimney of the locomotive and is formed by the two cones m and e.
The conc
e at its lower part is analogous to the suction cone e of Figure 7, with the difference,
however, that it is not the whole of the gases of the smoke box, but only the
greater part of them which pass through the cone e of Figure 9. The exhaust
steam from the cylinders is on issuing from the annular orifice guided internally
by the outer surface of the prolongation of the suction cone e, and draws the com-
bustion gases which ascend between the inner surface of p and the outer surface
of m. These gases mix with the steam and the mixture thereby formed ascends
with great rapidity and represents the propelling medium, which in passing through
the annular orifice formed by the upper edge of e and the inner surface of the
chimney, acts therein exactly as the compressed air in the apparatus shewn in
Figure 2, and draws with it the gases from the smoke box, the greater part of
which ascend through the suction cone e.
Figure 10 represents an arrangement which is worse than those of Figures 8

page_text: and 9, and still worse than those of Figures 5 and 7. By this arrangement however
the exhaust steam from the cylinders escapes by an annular orifice of a very favorable
diameter, since it is nearly as large as the inner diameter of the chimney; then the
exhaust steam from the cylinders, after having passed through the annular orifice,
has only a very small free course, as it is almost instantaneously taken up by the
inner surface of the chimney which thus acts as a guide to it; and lastly, owing to
the very large diameter of the drawing cone e, almost the whole of the combustion
gases are admitted into the hollow of the jet of steam which, being sufficiently
guided at its exterior by the chimney, effects the mixture with relatively not much
eddying.
The arrangement shewn in Figure 10 is therefore bad in comparison with those
shown in Figures 5 to 9, yet it is better than the escape apparatus referred to in the
earlier part of this Specification; the latter had indeed an annular orifice, but
the diameter of this annular orifice was not one half or not more than half of the
diameter of the chimney, and therefore relatively very small, so that the steam, after
having left the orifice, did not reach the inner surface of the chimney and therefore
was no longer guided.
The apparatus shewn in Figure 10 although much inferior to those shewn in
Figures 5 and 7 is therefore still an improvement.
Comparing therefore the above-described arrangements of chimney blast apparatus
for locomotives, Figures 8 and 9 are improvements on Figure 10, and Figures 5, 6,
and 7 are improvements on Figures 8 and 9.
It is hardly necessary to mention that in all these apparatus the arrangement of
the pipes a, a, depends upon the arrangement of the pipes which conduct the
exbaust steam from the cylinders. Figure 11 represents another example.
The arrangements of the improved chimney blast apparatus which are suitable
for locomotives can also be applied to the chimneys of boilers whose draft
should be assisted by the exhaust steam from the engine cylinders, and although
the application to such boilers is not of so great importance it will be found
advantageous.
In some cases the arrangements of chimney blast apparatus actuated by com-
pressed air, shewn in Figures 1, 2, and 3, could be employed with advantage to increase
the draft in the chimneys of stationary boilers or other large fire-places, but for such
purposes the chimney blast apparatus would naturally not be of so great importance
as for steamers, portable engines, or locomotives, the application to these latter con-
stituting a particularly important improvement.
The difference in the improvement obtained according to the application of the
apparatus is pointed out advisedly, because as the novelty of many Inventions not
only consists in the constructive parts of the apparatus but also in the new use to
which they are applied, in like manner the present Invention of improved chimney
blast apparatus is based not only on the different parts of which the apparatus is
constructed but also on the different applications or adaptations of the apparatus
as herein-before described.
And having now described the nature of the said Invention, and in what
manner the same is to be performed, I declare that I claim,―
First. The construction of chimney blast apparatus in such manner that there is
formed around the inner surface of the chimney an annular orifice of nearly the
same diameter as the chimney, by which compressed air or exhaust steam from
engine cylinders issues around the inner surface of the chimney, being continuously
guided and confined therein so as to form a hollow cone of air or steam, into the
interior of which hollow all the combustion gases of the chimney are conducted, so
that these are carried up by the said hollow cone of air or steam and conducted into
the open air, substantially as herein-before described.
Second. The employment in the chimneys of steam ships of blast apparatus
actuated by compressed air and constructed substantially as shewn in Figures 1, 2,
3, and 4, and herein-before described.
Third. The employment in the chimneys of locomotives of blast apparatus

page_text: constructed substantially as shewn in Figures 5, 6, 6ª, and 7, and herein-before
described.
Fourth. The employment in the chimneys of portable. engines, steamers which
work without condensation, and boilers in which the steam after having done its
work ordinarily exhausts freely, of blast apparatus actuated by exhaust steam, and
constructed substantially as shewn in the annexed Drawings, and herein-before
described.
Fifth. The employment in the chimneys of locomotives of blast apparatus
constructed substantially as shewn in Figures 8 and 9, and herein-before
described.
Sixth. The employment in the chimneys of locomotives of blast apparatus con-
structed substantially as shewn in Figure 10, and herein-before described.
In witness whereof, I, the said John Clayton Mewburn, have hereunto set
my hand and seal, this First day of February, One thousand eight hundred
and seventy-nine.
J. C. MEWBURN. (L.S.)