Appliances for Increasing the Efficiency and Evaporating Power of Tubular Steam Boilers.
Year: 1890

page_text: Date of Application, 6th Oct., 1890
Complete Specification Left, 4th July, 1891-Accepted, 3rd Oct., 1891
PROVISIONAL SPECIFICATION. ·
Appliances for Increasing the Efficiency and Evaporating Power of
Tubular Steam Boilers.
I, ERNEST PETERSEN, of 4 Beaumont Villas, Spring Grove, Isleworth,
Middlesex, Engineer, do hereby declare the nature of this invention to be as
follows:
In tubular boilers of present construction having horizontal or inclined fire tubes
fixed in tube plates, such as, more particularly, marine boilers; the tubes, in order
to allow of their being fixed in the tube plate by an expanding tool require to be
made of a large diameter and in order to afford the necessary heating surface, such
a number of them has to be employed that the collective sectional area offered
thereby for the passage of the combustion gases is many times greater than the
inlet area for air in the fire grate.
The result hereof is that the combustion gases mostly pass through the upper
rows of tubes, leaving the lowermost ones either entirely or partially inoperative,
and these consequently soon become choked with ashes.
My present invention consists firstly in adapting to the inlet ends of the fire
tubes appliances whereby the inlet area is greatly restricted and the entrance of
ashes more or less prevented and secondly in providing means at the outlet ends
of the tubes, in the smoke box whereby the draught is more or less equalized
throughout the tubes, so that by the above means a very uniform draught
through all the tubes is attained, resulting in a greatly increased evaporative power
thereof.
For this purpose, according to the first part of my invention, I fit into the inlet
ends of the fire tubes, mouth pieces or caps having one or more narrow long orifices
presenting considerably less area than the internal area of the tube. By preference
form such orifices in the following manner, I make the mouth piece, which is by
preference of fire clay, of a funnel or trumpet-mouth shape, with a cylindrical
extension of a size to fit easily into the mouth of the tube, and, while in a plastic
condition, bulge the funnel or trumpet-mouth inwards at three or more points so
as to reduce the mouth of the funnel to a narrow star shaped opening with three or
more branches. By this means the area of the inlet orifice is reduced to a very
great extent, and owing to the narrow shape of the openings combined with the
large amount of projecting outer surface offered by the mouth pieces, the ashes
that are carried with the draught will find great difficulty in entering the tubes,
the greater part being made to impinge against the outer surfaces of the mouth
pieces, from which they will fall back into the fire-grate again.
Also, as the area of the mouth piece begins to expand immediately beyond the
narrow orifice, the decreased velocity of the current will cause the dust particles to
fall on to the inclined inner surfaces along which they will descend and escape
through the orifice again.
Slits or small openings may be formed in the sides of the mouth pieces, which
will also serve for the escape of the ashes. Owing to the before mentioned
retarded flow of the combustion gases through the tubes as soon as they have
passed the orifice of the cap, owing to the increased sectional area, their heat will
be much more effectually transmitted through the tube to the water, resulting in a
correspondingly increased production of steam. The said mouth pieces will also
have the further beneficial effect of protecting the ends of the tubes from the
intense heat of the furnace, and consequently preventing them from wearing away,
and as the mouth pieces will become highly heated, the unconsumed portions of
combustible gases, in being brought into intimate contact at the narrow orifices

page_text: with portions of unconsumed air will enter into combustion therewith and thus
produce increased heat.
In carrying out the second above described part of my invention, which I
employ in combination with the method, of producing the necessary draught by
exhaust above the uptake, I close the smoke box immediately above the outlets of
the fire tubes by means of a plate, and from such plate suspend a number of
tubes, of varying lengths, so arranged that sets of the tubes extend down respectively
to the levels of each row of fire tubes.
By this means the exhaust produced above the said closing plate will produce a
draught through each set of hanging tubes at points close to the orifices of the fire
tubes, and thus by properly proportioning the diameters of the hanging tubes to
their length, the draught through the several rows of fire tubes can be rendered
practically uniform, instead of being very unequal as is the case when the smoke
box is entirely open to the exhaust above, which consequently in that case acts
more vigorously at the upper rows of tubes than at the lower rows.
The said suspended tubes may, for convenience of fixing and removal, be simply
provided at their upper ends with a pin passing through them, or with two opposite
external lugs, which are passed up through corresponding notches in holes in the
closing plate and which, on turning the tube one quarter round, then take a bearing
upon the upper surface of the said plate.
The suspended tubes may be prevented from swinging laterally by intermediate
lateral supports which may consist of bars with notches or holes into which the
tubes fit and which are carried loose in pockets at the ends so as to be easily
removeable.
The said hanging tubes may also be utilised for periodically removing any
deposits of ashes in the fire tubes.
For this purpose I provide above their upper ends two or more hinged flaps or
covering plates, which are ordinarily kept in a raised position, leaving all the upper
orifices of the hanging tubes free, but when it is desired to clear the tubes of dust,
the one flap is lowered so as to close the upper orifices of half the tubes, and the
draught through the other half being thus increased to a corresponding extent, the
dust will be drawn out of the corresponding fire tubes. On then closing the other
flap and opening the first one, the same operation will be effected with regard to
the other half of the fire tubes. For the periodical removal of any deposit of ashes
from the bottom plate of the smoke box, without the necessity of opening manholes
for this purpose, I provide a scraper connected at each end to a rod or chain,
passing through a hole in the side of the smoke box, so that by drawing the rod in
either direction, the dust is scraped into pockets which may either be detachable,
or may be provided with two slides that are opened and closed alternately in
the well known manner for discharging the contents, without leaving an opening
into, the smoke box.
Dated this 6th day of October 1900.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Appliances for Increasing the Efficiency and Evaporating Power of
Tubular Steam Boilers.
I, ERNEST PETERSEN, of 4 Beaumont Villas, Spring Grove, Isleworth,
Middlesex, 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:—
In tubular boilers of present construction having horizontal or inclined fire tubes
fixed in tube plates such as, more particularly, marine boilers, the tubes, in order
to allow of their being fixed in the tube plate by an expanding tool, require to be

page_text: made of large diameter, and in order to afford the necessary heating surface, such a
number of them has to be employed that the collective sectional arca offered thereby
for the passage of the combustion gas is many times greater than the inlet area for
air in the fire grate. The result hereof is that the combustion gases mostly pass
through the upper rows of tubes, leaving the lowermost ones either entirely or
partially inoperative, and these consequently soon become choked with ashes.
My present invention consists in adapting to the inlet ends of the fire tubes
appliances whereby, firstly, the inlet area of the tubes is greatly restricted, thereby
causing the draught to be very uniformly distributed throughout all the tubes ;
secondly, the entrance of ashes into the tubes is in great measure prevented;
thirdly, the unconsumed gases and smoke being brought into intimate contact with
the unconsumed air in the narrow inlets of the said appliances, which are heated to
a high degree, a more or less complete combustion of these gases will ensue, and
smoke will be prevented; fourthly, the said appliances will effectually protect the
ends of the tubes against burning away, and these will consequently last much
longer.
The said appliance consists of a cap or nozzle, by preference of fire-clay, one end
of which is formed cylindrical, both to fit into the end of the fire tube and over the
outer end thereof, while the other end of the nozzle which projects more or less
into the smoke box is provided with one or more narrow openings which present
considerably less area than the internal sectional area of the tube. By preference
I form such orifices in the following manner-I make the cap or nozzle of a funnel
or trumpet-mouth shape, with a cylindrical extension of a size to fit easily into the
mouth of the tube, and, while in a plastic condition, I bulge the funnel or trumpet.
mouth inwards at three or more points, so as to reduce the mouth of the funnel to
a narrow star shaped opening with three or more branches. By this means the
area of the inlet orifice is reduced to a very great extent, and owing to the narrow
shape of the openings combined with the large amount of projecting outer surface
offered by the nozzles, the ashes that are carried with the draught will find
great difficulty in entering the tubes, the greater part being made to impinge
against the outer surfaces of the nozzles, from which they will fall back into the
fire grate again.
Also, as the area of the nozzle begins to expand immediately beyond the narrow
orifice, the decreased velocity of the current will cause the dust particles to fall
onto the inclined inner surfaces, along which they will descend and escape through
the orifice again.
Slits or small openings may be formed in the sides of the mouth pieces, which
will also serve for the escape of the ashes. In consequence of the before mentioned
retarded flow of the combustion gases through the tubes as soon as they have
passed the orifice of the cap, owing to the increased sectional area, their heat will
be much more effectually transmitted through the tube to the water, resulting in a
correspondingly increased production of steam. The said nozzles are so formed as
to cover over the ends of the fire tubes, and thus have the further beneficial effect
of protecting these ends from the oxidising action of the flames, and consequently
preventing their rapid deterioration.
The before mentioned equalization of the draught throughout all the tubes by
the restricted orifices of the nozzles can be still more effectually carried out by
varying the sizes of such orifices in such manner that they are made of gradually
increasing area from the top downwards, so that greater resistance is offered to the
passage of the combustion gases through the upper rows of tubes than is the case
with the lower tubes.
The accompanying drawings shew the form of the before described cap or nozzle
which I prefer to employ.
Fig. 1 shews a perspective view of one of the nozzles.
Fig. 2 shews a longitudinal section of the same as fitted into an ordinary fire tube
and a stay tube.
Fig 3 shows a front view of a series thereof.

page_text: Fig. 4 shews a sectional plan of the same.
Fig. 5 and Fig. 6 shew respectively a front view and longitudinal section of the
nozzles fitted to compound fire tubes, such as were described in my Patent
No. 13556 of 1890, and
Fig. 7 shews a part longitudinal section of a boiler fitted with such tubes and
nozzles.
The fire clay nozzle or cap A widens out from the cylindrical part at a a¹, which
fits into and over the end of the fire tubes B, and stay tubes 13', to the star shaped
outer end ², so that it presents internally a passage for the gases of gradually
increasing sectional area from the narrow star shaped orifice at a² to the inner end.
The cylindrical part is formed with a shoulder a' in which is a circular groove into
which projects the end of the fire tube or stay tube when the nozzle is placed in
position, and as the said shoulder fits closely against the tube plate, it will be seen
that although the tube may become highly heated, it is protected against the
oxidizing action of the gases and will consequently not burn away. In the sides of
the nozzles, are, by preference, formed a series of small apertures a³ a³, which serve
both for the escape of any ashes that may have entered the narrow mouth of the
nozzle, and also for the entrance of further quantities of gases which, in impinging
upon those entering through the mouth, will produce a still more intimate mixture
thereof and consequently a more complete combustion.
For securing the nozzles in position in the tubes, I prefer in the case of new
boilers, or when boilers are supplied with new tubes, to make the ends of these
project sufficiently beyond the tube plate to allow a pin C to be passed through
such projecting end and through a hole in the tube as shown at Figure 2.
Or in
case of existing boilers, I form the ends of the nozzles with projecting lugs at a² ²,
Figure 3 which overlap bevilled surfaces formed on the next nozzle and thus hold
it in position, so that by merely replacing the top or the bottom tube of a vertical
row by a new one having a projecting end and securing the top or the bottom
nozzle in its place by a pin, as described, this will hold all the other nozzles of the
row in position.
Or again, two, four, six, or any other convenient number of the nozzles may be
formed into one block, as shewn at Figure 9, so that by replacing one only of the
six fire tubes by a new one with projecting end, the combined group of nozzles can
be secured by a single pin C as shewn.
By thus forming a number of the nozzles into one block an increased mass of
fireclay will be obtained, which will both retain the heat to a greater extent,
and will protect the tubes and tube plate still more effectually against corrosive
action.
With this arrangement, only some of the nozzles may be provided with the
cylindrical projections fitting into the tubes, the others being made to merely abut
against the ends thereof.
When the tubes are extended as described, whether in the case of ordinary tubes,
or of the said compound tubes, the advantages are obtained, firstly that they can
be effectually secured in the tube plates by bulging them on the outside as shown
at Figures 2 and 6, and secondly that such outer ends, in becoming expanded
on being heated, will tend to produce a tighter joint than with the ordinary
tubes.
When applying my said invention to boilers with ordinary fire tubes, I sometimes
employ, in addition, tubular fireclay insertions in the tubes as shewn in part
longitudinal section at Figure 10 and in cross section at Figure 11. These consist
of fire clay tubes D of such a size that the annular area left between them and the
sides of the fire tubes is about equal to the sectional area of the central opening of
the part a of the nozzles situated within the fire tubes. Thus the gases issuing
from the latter into the fire tube will not expand as they would do if the full area
of the fire tube were open, and consequently the cooling effect of such expansion is
avoided. The tubes are formed with a closed inner end and with oblique
perforations as shewn, so that the jets of highly heated gases or flame passing

page_text: into the central passage of such tubes, in issuing through such perforation both
impinge upon the surface of the fire tube, and mix with the gases passing through
the annular space, producing still more perfect combustion should any unconsumed
gases and air be left ameng the combustion products.
The tubes are held in a central position either by two opposite ribs D' which
are by preference formed helical as shewn, whereby the gases are made to take a
helical course through the tube and are thus retained longer in contact therewith;
or they may have projecting studs at intervals bearing against the surfaces of the
fire tube.
These tubes need only extend along a portion of the length of the fire tubes;
they are by preference made in short lengths, fitted together with dowel pins as
shewn; for facility of insertion and removal, the lengths are made with a screw
thread at one end into which can be screwed a key introduced from the front end
of the tube.
Although I prefer to construct the before described nozzles of the form shewn,
yet it will be evident that they may be made of various other forms, such as simply
cylindrical throughout with narrow openings in the side and end. Also, they might
be made of other material than fire clay, though this is preferred on account of its
durability.
It will be evident that, in addition to the first above described advantages of
the said nozzles, they will have the furthur beneficial effect, in shielding the
tube plate and ends of the tubes more or less entirely from the direct action of
the flames, of preventing the very energetic generation of steam upon these surfaces
such as occurs in tubular boilers and which prevents the maintaining of a solid body
of water against these surfaces, whereby they are liable to become overheated and
rapidly destroyed.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed 1 declare that what I
claim is:-
1. The construction and use of nozzles or caps of fire clay or other suitable
material, adapted to be fitted into the ends of the fire tubes of boilers, and so
constructed with narrow openings as to both restrict the entrance of the gases
into the fire tubes, and to effect a more complete combustion of the smoke and
gases with the unconsumed air passing in through them, substantially as described.
2. Constructing nozzles or caps for the fire tubes of boilers such as are
referred to in the preceding claim with the one end fitting into the tube and also
covering the outer end thereof, while the other end is formed with a narrow
star shaped orifice substantially as herein described with reference to the drawings.
3. Combining a number of the caps, or nozzles referred to in the preceding
claims into one block, substantially as described.
Dated this 2nd day of July 1891.
ABEL & IMKAI,
Agents for the Applicant.