CERTAIN IMPROVEMENTS IN STEAM GENERATORS
Year: 1875

page_text: LETTERS PATENT to Robert Renshaw, of the Oity of Manchester,
Engraver, for the Invention of "CERTAIN IMPROVEMENTS IN STEAM
GENERATORS."-A communication from abroad by David Renshaw,
of Cohasset, in the County of Norfolk and State of Massachusetts,
in the United States of America.
PROVISIONAL SPECIFICATION loft by the said Robert Renshaw at
the Office of the Commissioners of Patents, with his Petition, on
the 30th July 1875
I, ROBERT RENSHAW, of the City of Manchester, Engraver, do
hereby declare the nature of the said Invention for "CERTAIN IMPROVE-
MENTS IN STEAM GENERATORS," a communication to me from abroad by
David Renshaw, of Cohasset, in the County of Norfolk and State of
Massachusetts, in the United States of America, to be as follows
The object of this Invention is to reduce the cost of construction and
to economise space and fuel.

page_text: The improved steam generator consists of a reverberatory furnace
with a fire-grate and side flues containing pipes, on which are cast
flanges for other pipes, into which the lower ends of diagonal or curved
lap welded or other tubes are secured, the upper ends whereof are
secured to vertical pipes which communicate with a steam dome
There is a passage through the brickwork forming the outside of the
reverberatory furnace through which the air for supporting combustion
in the furnace is conveyed. The water circulates up and down through
the diagonal or curved tubes and the sediment is blown off through the
pipes in the side flues.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert Renshaw in the Great Seal Patent Office
on the 18th January 1876
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
RENSHAW, of the City of Manchester, Engraver, send greeting.
WHEREAS Her most Excellent Majesty. Queen Victoria, by Her
Letters Patent, bearing date the Thirtieth day of July, in the year
of our Lord One thousand eight hundred and seventy-five, in the thirty-
ninth year of Her reign, did, for Herself, Her heirs and successors,
give
and grant unto me, the said Robert Renshaw, Her special licenco
that I, the said Robert Renshaw, my cxccutors, administrators, and
assigns, or such others as I, the said Robert Renshaw, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, usc, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "CERTAIN IMPROVE-
MENTS IN STEAM GENERATORS," a communication to me from abroad by
David Renshaw, of Cohasset, in the County of Norfolk and State of
Massachusetts, in the United States of America, upon the condition
(amongst others) that I, the said Robert Renshaw, my executors
or administrators, by an instrument in writing under my, or their,
or one of their hands and scals, should particularly describe and
ascertam the nature of the said Invention, and in what manner the

page_text: same was to be performed, and cause the same to be filed in the
Great Seal Patent Office within six calendar months next and immo-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Robert Renshaw, do hereby
declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained in
and by the following statement (that is to say):—
The object of this Invention is to reduce the cost of construction and
to economisc space and fuel
1
The improved steam generator consists of a reverberatory furnace
with a fire-grate and side flues containing pipes, on which arc cast
flanges for other pipes, into which the lower ends of diagonal or curved
lap wolded or other tubes are secured, the upper ends whereof are
secured to vertical pipes which communicate with a steam dome. There
is a passago through the brickwork forming the outside of the rever-
beratory furnace through which the air for supporting combustion in
the furnace is conveyed. The water circulates up and down through
the diagonal or curved tubes and the sediment is blown off through the
pipes in the side flucs.
Fig. 1 is a front view of the improved steam generator in section, and
Fig. 2 is a vertical section of the same.
A is a reverberatory furnace provided with a grate B and drop flues C.
The bottoms of these flues are made a solid and good foundation to
support the longitudinal tube, pipe, or cylinder D This pipe DI prefer
to cast in a single piece, with flanged risers e to receive the flanged
projections or risers which start from and form a part of the pipe G.
This pipe GI also prefer to cast in a single piece On this pipe G I
cast bosses h, which are tapped for the proper reception of a screw
thread. The vertical pipes / are also of cast metal, with projections i
from each side of them. These pipes H may be drawn in somewhat
above the water line, so giving more surface to the flanges o. Into the
projections of the pipes H are screwed wrought-iron pipes or lap
welded boiler tubes J and K, which pipes are at their other extremity
connected with the pipes G by means of a lock nut union coupling or

page_text: The pipes J and K may be curved
3, and on an enlarged scale in
by any other of the usual modes
instead of straight, as shewn in Fig
Figs 4 and 5. This is the more common form of reverberatory furnace,
but the expense of curving them is saved in the form. shewn in the
other Figures.
The steam drum L is made of wrought iron, the projections M being
cast and bolted or rivetted to it by means of flanges in the usual way
practised in such constructions. The longitudinal pipes D are connected
at either front or rear, or at both, by a pipe N. By means of this pipe
N the boiler is fed and blown off. P is a passage way between the walls
of the furnace A to the ash-pit, having an inlet Q near the crown of
the furnace. By this means the air necessary for the support of com-
bustion and the furnace is drawn from the upper part of the boiler room,
which is thus kept at a lower temperature, less heat is radiated from the
furnace walls to the room, and a comparatively hot draught will be
furnished to the fire, the boiler of course being run with the ash-pit
door shut.
1
There is a gradual increase of heat from above the fire-line to the
apex of this furnace, therefore steam is generated most rapidly from the
upper portions of the boiler. For this reason this boiler can be made
with very small pipes or water bodies, and the priming or lifting of the
water will in all cases be prevented. The circulation is caused by the
difference of temperature above and below, and I construct these boilers
in such a way that the cubical contents of all the pipes J in one section
are about equal to the cubical contents of the pipe K in the same
section, or as nearly so as can practically be attained. By this means
the water receives most heat in its passage upward through the pipes J,
and hence its downward passage in the pipe K. The cubical contents of
the pipes J and pipe K being about equal is guarantee that the entire
water of the boiler is in motion. All the surfaces of this boiler are
downwardly inclined Sediment is heavier than the water in which it is
formed, and hence by its own density is carried from each section to the
bottom of the pipes D, which are so located that such sediment cannot
be burned fast to them; hence this boiler is surpassed by none for
cleaning facilities.
It will be noticed that the sections are tied together by and have their