Improvements in Multitubular Boilers.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improvements in Multitubular Boilers.
JOHN SCOTT Marine Engineer 31 Hill Street Jarrow-on-Tyne do hereby declare
the nature of this invention to be as follows:-
To improve the efficiency of multitubular boilers by means of an arrangement to
regulate the velocity of the heated gases and thereby cause а more perfect
combustion and better distribution of the same, also by retaining the heated gases
longer in contact with the heating surfaces of the combustion chambers and tubes.
This regulation is to be effected by the following methods, either used separately
or together.
1st. The area of the tubes is to be reduced at the front or delivery ends, by
means of suitable portable pieces of iron (or other material) inserted therein.
2nd. Or by means of portable plates so placed across the front ends of the tubes,
that the area of the tubes can be regulated as required.
3rd. Or by means of portable plates so placed in the smoke boxes, that the gases
on leaving the tubes will be directed downwards before passing into the funnel.
These plates will be so arranged that either all, or only a portion of the gases
will be so directed downwards.
By any of these methods the area through the tubes will be so arranged, that
the least area will be through the top or upper row, and increase proportionally
downwards.
Dated this 21st day of December 1895.
Improvements in Multitubular Bollers.
1, JOHN SCOTT, of 31 Hill Street, Jarrow-on-Tyne, Marine 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 :-
The object of this invention is to cause the products of combustion to pass as
uniformly as possible through all the smoke-tubes of a multi-tubular boiler, that is
to say, to ensure that practically the same quantity of products of combustion shall
pass through the lower rows of tubes as through the upper rows and thereby render
all the tubes practically equal to one another in evaporative efficiency.
For this purpose I provide the front or smoke-box ends of the tubes with
removable draught regulating devices adapted to partly close such tube ends, the
closing devices for the successive rows being of different depths so that the tubes
of one row are closed to a greater extent than those of the next lower row.
Fig. 1 of the accompanying drawings is a front elevation showing the smoke box
ends of the tubes of a multi-tubular boiler provided with one arrangement of draught
controlling apparatus according to this invention. In the example shewn in Fig. 1
of this arrangement the tubes 1 of all the rows, except the lowest three rows, are

page_text: partially closed at their outlet ends by pieces or plugs 2 of suitable material such as
iron, one of which is shown to a larger scale in front elevation, longitudinal section,
and back elevation in Figs. 2, 3 and 4 respectively, and each of which consists in
the example shown, of a part tube closed at its outer end by a flange 2". It will
be seen that the end flanges 2ª of the plugs 2 of the several rows gradually decrease
in depth from row to row in a downward.direction, the lowest rows of tubes in this
case (Fig. 1) being without closing devices. The number of rows of tubes without
closing devices may differ in different cases according to the varying condition of
working. In this way the velocity of the escaping hot gases passing through the
upper tubes is regulated with the result that the gases are retained longer in
contact with the heating surfaces of the combustion chamber or chambers and of
the tubes, than would be the case if all, the tubes were left. full open, whereby
'there is a more perfect combustion and a better distribution of the hot gases, both
in the combustion chamber or chambers, and in the tubes, thereby considerably
increasing the evaporative efficiency of the boiler.
The plugs 2 of each row are secured by their flanges 2ª to a common bar 3. in
order that they may be easily and quickly removed to allow of the cleaning of the
corresponding row of tubes, or of stopping one or more tubes should the same
become defective.
Fig. 5 is an elevation and Fig. 6 a vertical section showing a modified-arrangement
in which the draught regulating devices are in the form of flat plates or dampers 4.
rigidly secured to bars 5 which are mounted in suitable, supports 6 so as to be capable
of being partly rotated by means of a rod 7 connected to arms 8. fixed to the said
bars 5. As in the arrangement herein before described, the depth of the dampers
opposite each row of tubes 1 is such that the upperinost row is closed to a greater
extent than the next lower row, and this row to a greater extent than the next
⚫lower row and so on downward, and this will continue to be the case if the dampers
be turned partly outwards so as to allow the products of combustion-to-pass-through
the tubes more freely should this be found necessary. Also, after steaming for
some time, by fully opening the dampers for a short period, the tubes can be
partially cleared of soot by reason of the greater draught then passing through them,
thereby obviating the necessity of sweeping the tubes.so often in the ordinary manner
whilst the boiler is under steam. Suitable means, such as bell-cranks, rods, and
levers, are provided for enabling the rod 7 to be operated from any convenient
position by the attendant.
It is not necessary that all the tubes in the same horizontal row should be equally
closed so long as they be closed to a greater extent than the tubes in the next
lower row.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that I do not
claim broadly the application, of separate draught regulating devices to the front
or outlet ends of the smoke tubes of multi-tubular, boilers, but what I do claim is :-
-
1. A. multi-tubular boiler in which rows of smoke tubes are partially closed at
their. front or delivery ends by draught. regulating devices applied to, each of the tube
ends separately, the said devices for. successive horizontal rows of tubes being of
different, depths so that tubes in the same horizontal row are closed to a greater
extent than the tubes.in. the next: lower row.and.so.on downward, so that. the velocity
of the escaping hot gases passing, through the rows of tubes provided with the
said devices will be regulated, substantially as herein. described for the purpose
specified.
2. A multi-tubular boiler shaving.the. front. or delivery..ends of, its smoke tubes
provided with draught regulating devices .constructed, arranged and operating
substantially as herein before described with.reference.to and shown in Figs. 1 to 4
inclusive of the drawings annexed.
3. A multi-tubular boiler having the front or delivery.ends of its smoke, tubes

page_text: provided with draught regulating devices constructed, arranged and operating
substantially as hereinbefore described with reference to and shown in Figs. 5 and 6
of the drawings annexed.
E
1
For the Applicant,
3333
was too way of Doptember 1050.
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.