Improvements in Steam Generators.
Year: 1890

page_text: Date of Application, 5th Nov., 1890
Complete Specification Left, 5th Aug., 1891-Accepted, 5th Sept., 1891
PROVISIONAL
SPECIFICATION.
Improvements in Steam Generators.
I, JOHN ISAAC THORNYCROFT, of Church Wharf, Chiswick, in the County
of London, W., a member of the firm of J. I. Thornycroft & Co. Steam Yacht
and Launch Builders, do hereby declare the nature of this invention to be as
follows:-
My invention relates to steam generators of the kind wherein water is exposed
to the action of heat while passing in tubes between two vessels one of which acts
as a steam collector and separator as for example in the generator described in
the Specification of a former Patent granted to me namely No. 1404 dated
31st January 1885.
In a steam generator according to my present invention the fire box is divided by
a longitudinal vessel I will call for distinction the main water vessel that is connected
by a row or rows of tubes with the lower part of the steam collector and separator,
and by other tubes, suitably bent, with the upper part of the steam collector and
separator. The outer walls of the fire-box are formed by suitably bent tubes con-
nected at their upper ends to the upper side of the steam collector and separator,
and at their lower ends to longitudinal supplementary water vessels that are in turn
connected by suitable pipes with the main water vessel. The tubes are so arranged
that at each side of the lower portion of the steam collector and separator and of
the tubes that connect such lower portion with the main water vessel, a passage
is formed that is bounded by bent tubes which connect the main water vessel
with the upper side of the steam collector and separator, and at one end (or.
in some cases both ends) each of these passages is in communication with a
chimney.
With the above described arrangement the principal groups of tubes are
located between two fires there being only one wall of tubes at each outer side
so that there shall not be liability to any of the rows of tubes being cooled and
the circulation therein being thus stopped or impaired. Furthermore, by causing
the gases to escape from between the tubes at the end (or ends) of the generator,
they are made to pass between the tubes near to the water level and thus the upper
parts of the tubes will not be liable to overheating. The arrangement, moreover,
by utilizing the space enclosed by the tubes at each side of the lower part of the
steam collector and separator as a smoke box for collecting the gases on their way
to the chimney will tend to improve the evaporative efficiency and at the same time
enable a generator of a given power to be placed under coal bunkers or in other
situations where the height available is limited.
In the above described construction of boiler it is advantageous to make the
tubes that are connected to the upper sides of the steam collector and separator
of a simple curved form consisting to a large extent of one bend of constant radius
and with straight ends simply but slightly bent at the extremities to adapt them
to fit the varying angles of the holes in the tube plates thus tending to reduce cost.
It will usually be advantageous to impart a bended form to the tubes connecting
the lower part of the steam collector and separator with the main water vessel and
then in some cases they may be simply secured by a mandril. The chimney
may be attached to the fire end of the boiler or to the opposite end, and large
boilers might be adapted to be fired at both ends. It is advantageous to supply
the feed water to the steam collector and separator in order to aid the descent of
water through the tubes connecting this vessel with the main water vessel, the feedl

page_text: pipe or pipes being so arranged as: to cause the feed water to be distributed as
uniformly as practicable to-the several tubes:..
Dated this 5th day of November--1890.
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, WC, Agent for the Applicant.
COMPLETE SPECIFICATION...
Improvements, in Steam Generators.
I, JOHN ISAAC THORNYCROFT, of, Church Wharf, Chiswick, in the County of
London, Wa member of the firm of I. Thornycroft & Co. Steam-Yacht and
Launch Builders, do hereby declare the nature of this invention and in what manner 10
the same is to be performed to be particularly described and ascertained in'-and-by-
the following statement:-
My invention relates to steam generators of the kind wherein water is exposed to
the action of heat while passing in tubes between two vessels one of which acts as
a steam collector and separator, as for example in the, generator described in' 15
the Specification of a former Patent granted to me namely No: 1404-dated
31st, January 1885.
In a steam generator according to my present invention the fire box is divided
by a longitudinal vessel which I will call for distinction the main water vessel that
is connected by a row or rows of tubes with the lower part of 'the steam collector.20
and separator, and by other tubes suitably bent, with 'the upper part of the steam
collector and separator. The outer walls of the fire box-are formed by suitably
bent tubes connected at their upper ends' to the upper side of the steain collector
and separator, and at their lower ends to longitudinal supplementary water.
vessels that are in turn connected by suitable pipes with the main water 25
vessel. The tubes are so arranged that at each side of the lower portion of the
steam collector and separator and of the tubès that connect such lower portion
with the main water vessel à passage is formed that is bounded by bent tubes which
connect the main water vessel with the upper side of the steam collector and
separator, and at one end (or in some cases both ends) each of these passages is in 30
communication with a chimney..
In order that my present improvements may be clearly understood, reference is
had to the accompanying illustrative drawings in which
Fig. 1 shows partly in transverse section and partly in front-elevation and
Fig. 2 in central longitudinal vertical section, a steam generator constructed 435
according to this,invention.
Fig. 3 is a side elevation of the generator with a portion of the casing removed".
and, with a part of the main water, vessel in section.
Figs. 4 and 5 show in vertical section and plan respectively, a convenient mode.
of connecting the lower ends of the tubes forming the outer walls of the fire-boxes 40
to the supplementary water vessels, which will usually be too small to permit of the
tubes being fixed therein by a mandril in the, usual.inanner.
1, is a horizontal steam, collector and separator; 2 is a horizontal cylindrical
water vessel; forming what is herein called the main water vessel 3,3; are fire
grates arranged one at each side of the main water vessel' 222 are supple 4
mentary water vessels arranged at the outer sides of the fire grates and each in
communication with the main water, vessel; 4, 4, are two series of bent tubės:
connecting the main water vessel 2 with the upper part of the steam; collector and
separator; 4* 4* are two series of bent tubes connecting the supplementary water
vessels 2ª with the upper part of the steam, collector and separator and 5, 5-are-50
return tubes connecting, the, main water vessel 2 with the lower side of the steam-
collector and "separator 1. The two series of bent tubes 4 are arranged as shown
so as to form, a passage, or smoke box 6 between them that extends the whole
length of the generator and communicates at one end with a chimney 7. The smoke-

page_text: box is bounded by the tubes 4, the underside of the steam collector and separator 1,
and the top of the main water vessel 2, and through it the return tubes 5 pass as
shown. 8, 8 are bent plates extending longitudinally through the smoke box so as
to divide the same into three parts ., two outer ones that serve for the passage
of the hot gases to the chimney, and an intermediate one in which are located the
return tubes 5.
By this construction the return tubes are protected from direct contact with the
hot gases flowing through the smoke passages and the downward flow of water
through them is thereby facilitated. The two series of tubes marked collectively 4
(Fig. 1) are so bent and arranged that some of the tubes of each series are arranged
close together for the greater part of their length to form inner and outer
longitudinal tubulous close walls A and B respectively of a flue C, and are bent at
other parts to form inlet and outlet spaces 9 and 10 as described in my said former
Specification, and within each flue thus formed the remaining pipes of the series
are arranged, either separately, as described in the said former Specification, or so
that the pipes of every two rows are made to form a single longitudinal row of
pipes except near their ends as shown in Fig. 1. The plates 8 serve, in addition
to protecting the return tubes 5, to prevent the direct escape of hot gases from the
flues C into the smoke box 6 through the spaces between the lower ends of the
tubes 4 forming the inner walls B of the flues. Each series of bent tubes *4*
consists, at the extremities, where connected to the steam collector and separator 1
and supplementary water vessel 2ª, of two rows whose intermediate portions merge
into one row that constitutes a wall of closely arranged tubes.
In the example shown, each supplementary water vessel 2ª is formed with a
bend 2 and is in connection therethrough with the main water vessel 2 as indicated
in Figs. 1, 2 and 3. The wall of tubes 4* extends along the bent portion of the
supplementary water vessel as represented. Each series of tubes 4* is arranged to
touch the tubular wall A of the adjacent series of tubes 4 at A* so as to practically
close the top of the fire box. Flame and hot gases pass from each fire box through
the spaces 9 at the bottom of the wall A. of tubes into the corresponding flue C
and thence escape through the spaces 10 at the top of the inner wall B of tubes.
into the smoke box 6 and chimney 7. The front ends of the fire boxes, and those
parts of the rear ends not closed by the tubes 4* are closed, except opposite the
fire doors, by fire brick. 11, 11 are metal casings enclosing the tubes 4 and 4* and
the front of the generator.
With the above described arrangement the principal groups of tubes viz. the
groups 4, 4, are located between two fires there being only one wall of tubes cic. 4*
at each outer side, so that there shall not be liability to any of the rows of tubes
being cooled, and the circulation therein being thus stopped or impaired. Further-
more, by causing the hot gases to escape from the flues C into the smoke box 6
through the spaces 10 at the upper end of the inner wall B of tubes, instead of
through the outer wall at D as heretofore, they are made to pass between the tubes
near to the water level in the steam collector and separator, and thus the upper
parts of the tubes will not be liable to overheating. The arrangement, moreover,
by utilizing the space enclosed by the tubes 4 at each side of the lower part of the
steam collector and separator as a smoke box or boxes for collecting the gases
on their way to the chimney, improves the evaporative efficiency, and at the
same time enables a generator of a given power to be placed under coal bunkers
or in other situations where the height available is limited and would not
accommodate a generator of the same power and similar class as heretofore usually
constructed.
In the above described construction of steam generator i is advantageous to
make the tubes 4 of the simple curved form shown consisting to a large extent of
one bend of constant radius, and with straight ends simply, but slightly bent near
the extremities to adapt them to fit the varying angles of the holes in the steam
collector and separator and the main water vessel thus tending to reduce cost.
It will usually be advantageous to impart a bended form to the return tubes s

page_text: j.
as shown in Figs. 2 and 3 to allow for change of form of the steam collector and
separator and the main water vessel, due to local heating of these parts, and then
they may be simply secured by a mandril or tube expander. The chimney 7 may
be attached to the fire door end of the boiler; or to the opposite end as in the
example shown; large boilers might be adapted to be fired at both ends in a manner
that will be readily understood without drawings.
The steam collector and separator is provided with any suitable arrangement of
baffle plate or plates, for example the plates 12, against which jets of mixed water
and steam are projected from the upper ends of the tubes 4 and 4* when the
generator is at work, the water falling to the lower part of the steam collector
and separator and thence through the return tubes 5 and water vessels 2 and 2 to
the tubes 4 4*, wherein it is further heated. The steam passes under the lower
edges of the baffle plate or plates and enters a perforated steam pipe 13 whence it
can be conducted away for use. Suitable constructions of baffle plates are described
and shown in my said former Specification and in the Specification of an application
for Patent filed by me dated 11th October 1890 No. 16183.
14 is a pipe for supplying feed water, which it is advantageous to admit to the
steam collector and separator in order to aid the descent of water through the
return tubes 5. To this end also the feed pipe is perforated at its underside and
arranged to extend longitudinally within the steam collector and separator so as to
cause the feed water to be distributed as uniformly as practicable to the several
return tubes.
The lower ends of the tubes 4* may advantageously be secured to the small
supplementary water vessels 2", by a union of the construction shewn in Figs. 4
and 5 and comprising a socket 15 formed with internal screw thread 17 and with an
externally screw threaded tubular part 16 screwed into the wall of the steam
collector and separator and water vessel as the case may be. 18 is a gland screwed
into the socket 15 between which and the inner end of the gland, the flange 19 of
the tube (4 or. 4*) is firmly held steam tight.
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 what I
claim is
1. In a steam generator of the kind herein referred to, a steam collector and
separator, a main water vessel in communication therewith and arranged between
two fire boxes, supplementary water vessels in communication with the main water
vessel and arranged one at the outer side of each fire box, and bent tubes connecting
each of the said water vessels with the upper part of the steam collector and separator
so as, to form the sides and top of the two fire boxes, and, in conjunction with the
steam collector and separator and main water vessel, an intermediate smoke box
having an outlet at one or at each end thereof substantially as herein described.
2. In a steam generator of the kind referred to in the preceding claim, the
peculiar arrangement substantially as described of the principal groups of tubes in
two series located between the two fire boxes (one series at each side of the smoke
box) so that some of the tubes of each series constitute inner and outer longitudinal
tubulous close walls and form the flues within which the other tubes of the scries
are placed, inlets being provided to the bottom of the said flues, and outlets from
the upper part of such flues into the smoke box being formed at points corresponding
approximately to the level of the water in the steam collector and separator as set
forth for the purpose specified.
3. In a steam generator of the kind herein referred to, the combination of a
steam collector and separator, a main water vessel, two supplementary water vessels,
bent' tubes such as 4 and 4* that connect the upper part of the steam collector and
separator with the said water vessels so as also to form two fire boxes and a smoke
box, and return tubes which connect the steam collector and separator with the
main water vessel and are arranged to extend downward through the smoke box
substantially as herein described.

page_text: 4. In a steam generator of the kind herein referred to, the described arrangement
of a steam collector and separator, two water vessels 2, 2" and bent connecting
tubes 4 4 wherein the upper portion of one side of the steam collector and
separator is connected with both of the said water vessels namely by the bent
tubes 4 at that side with the one water vessel 2ª and by the other bent tubes 4 at
the same side of the steam collector and separator with the other water vessel 2;
the arrangement being such as to form a fire box with wall of tubes 4* and roof
and side A as well as a flue C whereof A. is one tubulous wall and B the other;
there being provided inlets to the said flue from the fire box at 9 also suitable
outlets from the flue and connections for returning water to the vessels 2 and 2ª as
explained.
5. My improved steam generator constructed and arranged as described and
shewn.
Dated this 4th day of August 1891.
W. Lloyd Wise,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.