Improvements in Apparatus for Increasing the Draught of and Promoting Combustion in Steam Boiler Furnaces.
Year: 1893

page_text: Date of Application, 28th Sept., 1893
Complete Specification Left, 28th June, 1894-Accepted, 28th July, 1894
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Increasing the Draught of and
Promoting Combustion in Steam Boiler Furnaces.
I, JOHN MACKLIN ALLAN, of Oakbank, Shandon, Dumbartonshire, Engineer,
do hereby declare the nature of this invention to be as follows:-
This invention relates to apparatus for increasing the draught of and promoting
combustion in steam boiler furnaces.
At present, with what are known as forced draught apparatuses air is forced
under pressure directly into the furnace or combustion chamber of the boiler and
not into the boiler tubes.
In my invention the air, whether under pressure or not is forced or allowed to
pass directly into the boiler tubes so as to promote combustion therein and thereby
increase the effective heat of the boiler.
The invention may be carried out in various ways but I prefer to fit in the
combustion chamber one or more air tubes or pipes which may be arranged
vertically or horizontally between the rows of boiler tubes. The air pipes are
provided with jet orifices, nozzles or nipples or with small tubes through which the
forced draught is delivered into the tubes of the boiler. Air under pressure is
supplied to the air pipe or pipes from a fan, blower or air compressor.
The air pipe or pipes may be so made and fitted as to be easily altered or
replaced.
If desired the air pipe or pipes may be passed from the smoke box through one
or more of the boiler tubes to the combustion chamber and in such case the
pipe or pipes may be perforated throughout a part or the whole of their length.
If desired, the forced draught may be dispensed with and an induced current of
air be merely drawn through the air pipe or pipes into the boiler tubes. In
this case the extra supply of air tends to promote combustion and to lessen
smoke.
The air pipe or pipes may be enclosed in an annular casing. or covering to protect
them from being burned by the heat, or they may be covered with asbestos or a
like uon-conductor.
The air pipe or pipes may be fitted obliquely or otherwise in the combustion
chamber and be made or constructed in any suitable and well known manner.
As the air pipe (or pipes) is fitted in the combustion chamber it is always very
hot and the air passing through it (or them) is therefore highly heated.
It is to be understood that I do not confine myself to any precise arrangement or
construction of the air pipes and delivery nozzles, etc.
Dated this 27th day of September 1902.
Brok
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.

page_text: Improvements in Apparatus for Increasing the Draught of and
Promoting Combustion in Steam Boiler Furnaces.
I, JOHN MACKLIN ALLAN of Oakbank, Shandon, Dumbartonshire, 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:-
This invention relates to apparatus for increasing the draught of and promoting
combustion in steam boiler furnaces.
At present, with what are known as forced draught apparatuses air is forced
under pressure directly into the furnace or combustion chamber of the boiler and
not into the boiler tubes.
In my invention the air, whether under pressure or not is forced or allowed to
pass directly into the boiler tubes so as to promote combustion therein and thereby
increase the effective heat of the boiler.
The invention may be carried out in various ways but I prefer to fit in the
combustion chamber one or more air tubes or pipes which may
be arranged
vertically or horizontally between the rows of boiler tubes. The air pipes are
provided with jet orifices, nozzles, or nipples or with small tubes through which
the forced draught is delivered into the tubes of the boiler. Air under pressure
is supplied to the air pipe or pipes from a fan, blower, or air compressor.
The air pipe or pipes may be so made and fitted as to be easily altered or
replaced.
And in order that my said invention may be properly understood I have hereunto
appended an explanatory sheet of drawings, whereon,
Fig. 1 is a vertical section of a marine boiler having my invention applied
thereto.
Fig. 2 is an enlarged sectional plan taken on the line of Fig. 3.
Fig. 3 is an enlarged view showing the method of fitting the air pipes in a
boiler.
•
Fig. 4 shows a blast box having curved blast pipes fitted therein.
Referring to the drawings:-
a are the air blast pipes which are secured at their upper ends in sockets on the
lower side of an air blast box b which is fitted in the crown of the combustion
chamber c.
The blast box is provided with a passage way d the mouth of which
fits into the end of one of the upper row of boiler tubes e.
A pipe from a fan, blower or air compressor is led into the smoke box and its
end is inserted into the back of the tube e (see Figs. 1 and 2).
The air pipes a are provided at intervals with holes g, or nozzles, through
which the blast is delivered into the boiler tubes. As shown at Fig. each air
pipe a is preferably fitted between two vertical rows of boiler tubes and the
holes g are arranged in pairs so as to deliver the blast into the boiler tubes at each
side.
The pipes a are preferably supported at their lower ends by brackets i.
Although it is not essential that the joints should be tight I prefer to make them
so by means of fireclay j as shown.
The pipes a may be either straight as shown at Figs. 1 and 3 or curved at their
upper ends as shown at Fig. 4. In the latter case the pipes are secured at their
upper ends in the side of the blast box instead of into the bottom as in the former
case.
The projecting passage way d which is inserted into the boiler tube e serves to
support the blast box b
As will be seen the pipes a can be easily removed and replaced.

page_text: The air which is delivered into the blast box b under pressure escapes from the
holes g and promotes a considerable draught through the boiler tube, thereby greatly
increasing the combustion of the fuel.
If desired the air pipe or pipes may be passed from the smoke box through one
or more of the boiler tubes to the combustion chamber, and, in such case, the
pipe or pipes may be perforated throughout a part or the whole of their length.
If desired, the forced draught may be dispensed with and an induced current
of air be merely drawn through the air pipe or pipes into the boiler tubes. In
this case the extra supply of air tends to promote combustion and to lessen
smoke.
The air pipe or pipes may be enclosed in an annular casing or covering to
protect them from being burned by the heat; or they may be covered with asbestos
or a like non-conductor.
The air pipe or pipes may be fitted obliquely or otherwise in the combustion
chamber and be made or constructed in any suitable and well known manner.
As the air pipe (or pipes) is fitted in the combustion chamber it is always very
hot and the air passing through it (or them) is therefore highly heated.
It is to be understood that I do not confine myself to any precise arrangement or
construction of the air pipes and delivery nozzles, etc.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
1 consider novel and desire to claim is :-
The improved construction of apparatus for increasing the draught and promoting
combustion in steam boiler furnaces, substantially as hereinbefore described with
reference to the drawings annexed.
Dated this 27th day of June 1894.
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.