Improvements in or connected with Tubular Steam Generators and Tubes therefor.
Year: 1893

page_text: Date of Application, 11th May, 1893
Complete Specification Left, 25th Sept., 1893-4ccepted. 5th May, 1894
PROVISIONAL SPECIFICATION.
Improvements in or connected with Tubular Steam Generators and
Tubes therefor.
I, ALEXANDER SIME, of Lambayeque, Peru, Mechanical Engineer, do hereby
declare the nature of this invention to be as follows:-
This invention has reference to steam generators of the tubular type, and to
tubes for such steam generators, wherein the tubes run from one tube plate to
another, and the gases of combustion pass through them, the water to be heated
and converted to steam surrounding said tubes; and one of the chief objects of my
invention is to so fit and construct the tubes, that the constant difficulty found to
exist in steam generators of this kind employing high pressure steam, namely,
leakage at the joint of the tube and tube plate at the hotter end (that is the
combustion chamber end tube plate), shall be obviated.
According to the present invention, chiefly to obviate the defect referred to, I
provide relatively more space for the circulation of water over the surface of the
combustion chamber tube plate, and the hottest part of the tubes at that end, by
the employment of tubes of smaller diameter at the parts nearest the said tube
plate than the main and greater portion of said tubes; and further, the tubes at
their ends are in the form of a turned back collar, leaving an annular space for the
entrance and circulation of water between the narrower part of the tubes, and the
collar. This collar may be made of the full diameter of the tube, or larger, and
screwed into the tube plate. By this construction, the heat entering the tube
plate can pass more rapidly into the water, and thus the said plate and tube end
are prevented from becoming overheated.
I also under this invention provide a certain amount of freedom for expansion
and contraction of the tubes, and this I do by providing an inset or shoulder at the
part where the tubes are reduced in diameter, at which part longitudinal extension
and contraction can take place.
The opposite ends of the tubes, that is the smoke box ends, may be secured to
the tube plate at that end in any known suitable way.
By the employment of tubes as above described, every tube will serve as a stay
to the tube plates; and thinner tube plates can be used with safety and without
liability of buckling.
With respect to the annular water space at the end of the tube, since in all
cases where high pressure steam is employed, fresh or distilled water only is used,
the liability of their becoming choked or filled or incrusted with deposited matter,
will not exist.
With respect to the ability of the joint of the tube and tube plate, at the
combustion chamber end, to retain its tightness and efficiency under high pressure
and great heat, the holes in the tube plate, as well as the screwed end of the tubes,
being slightly tapered are jointed only after the holes in the plate have been heated
to smoking oil test (after which the tubes are screwed firmly), this tightness is
assured.
CHEESBROUGH & ROYSTON, Fels. Chart. Inst. P.A.,
15, Water Street, Liverpool, Applicant's Patent Agents.

page_text: Improvements in or connected with Tubular Steam Generators and
Tubes therefor.
I, ALEXANDER SIME, of Lambayeque, Peru, Mechanical 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 has reference to steam generators of the tubular type, and to
tubes for such steam generators, wherein the tubes run from one tube plate to
another, and the gases of combustion pass through them, the water to be heated
and converted to steam surrounding said tubes; and one of the chief objects of
my invention is to so fit and construct the tubes, that the constant difficulty found
to exist in steam generators of this kind employing high pressure steam, namely,
leakage at the joint of the tube and tube plate at the hotter end (that is the
combustion chamber end tube plate), shall be obviated.
According to the present invention, chiefly to obviate the defect referred to, I
provide relatively more space for the circulation of water over the surface of the
combustion chamber tube plate, and the hottest part of the tubes at that end, by
the employment of tubes of smaller diameter at the parts nearest the said tube
plate than the main and greater portion of said tubes; and further, the tubes at
their ends are in the form of a turned back collar, leaving an annular space for the
entrance and circulation of water between the narrower part of the tubes, and the
collar. This collar may be made of the full diameter of the tube, or larger, and
screwed into the tube plate. By this construction, the heat entering the tube
plate can pass more rapidly into the water, and thus the said plate and tube end are
prevented from becoming overheated.
I also under this invention provide a certain amount of freedom for expansion
and contraction of the tubes, and this I do by providing an inset or shoulder at the
part where the tubes are reduced in diameter, at which part longitudinal extension
and contraction can take place.
The opposite ends of the tubes, that is the smoke box ends, may be secured to the
tube plate at that end in any known suitable way.
Tubes arranged and constructed as above described are shewn in the accompanying
drawings which serve to illustrate my invention.
Figure 1 shews one form of tube according thereto in section; and Figures 2 and 3
shew two other modifications of tubes under the invention.
The tube shewn in Figure 1 of the drawings possesses the characteristics above
described, that is to say, it consists of a larger portion a, which is the normal size
of a tube, say for example of about 2 to inches in diameter-and a smaller
part b, the end of which is secured in the combustion chamber tube plate
designated c, this part being of about from 1 to 2 inches diameter. These
characteristics exist in all the modifications of tubes shewn. The construction of
the end of the tube shewn in this figure-Figure 1-at which it is fastened in the
tube plate c consists of a turned back collar d, leaving an annular space e round the
greater part of the tube which lies between the front and back faces of the tube
plate c. In this annular space the water is free to enter and circulate, and so keep
that portion of the tube within the tube plate and subject it to the greatest heat
sufficiently cool to obviate damage thereto by erosion or other deterioration by
such heat. The collar d is threaded externally, and the hole in the plate e internally
and the tube is fastened by screwing into it from the smoke-box end.
At the part where the portions of greater and less diameters meet, a shoulder fis
provided, that is the junction or point of union is made in the form of a shoulder,

page_text: by which construction a certain amount of longitudinal freedom for expansion and
contraction of the tubes is provided. The portion a of the tube between the
shoulder and the smoke-box tube plate is of the full diameter, and is secured to
the tube plate in any known suitable way.
The tube shewn in Figure 2 is similar to that shewn in Figure 1, with the
exception of the end of the part 6 which is fastened in the tube plate, which, in this
case, is a simple continuation of the part 6 threaded and screwed into the tube-
plate; or it may be expanded solely therein in the ordinary way. In addition to
securing the tube ends by screwing them into the tube plate c, such ends, or some
of them, may project beyond the tube plate on the furnace side, and have a nut
screwed onto same.
b
The construction of tube shewn in Figure 3 is a modification mainly in respect
of the point where the smaller and larger parts meet. It consists in making the
part a and the part 6 separate, and providing the former with a socket f, having
preferably a shoulder f onto which the part b abuts when screwed up. The form
of the end of the part of the tube 6 which is secured to the tube plate is the same
as that set forth with reference to Figure 1 with the exception, that it is plain
instead of screwed, and is slightly tapered downwards from the fire side. This
arrangement or construction provides for securing the smaller part 6 from the
combustion chamber end, and the other part a from the smoke-box end, and
latter being screwed into the smaller part 6 from the smoke-box end. As regards
the ends of the parts b which fit in the plate c, these may in all cases with
advantage be slightly tapered; and previous to securing them in the hole in the
tube plate, or when so doing, the tube plate may be heated to a smoking oil
test, whereby a sure fit and secure joint is effected.
A tubular steam generator provided with tubes constructed as herein set forth
affords a much greater space between the tubes at and near the combustion tube
plate and greater area of the tube plate on which the water could pass and act, for
any given pitch of tubes, than can be obtained by ordinary tubes, and sufficiently
large to allow such a volume of water to pass or circulate over these parts of the
tubes and the tube plate, as obviates all leaking of tubes, bulging of tube plate, and
other defects, such as happen when using high pressure steam in ordinary marine
tubular steam generators. Moreover, it enables tubes to be pitched closer together
than is at present practically possible, as, if this be done as close as possible, the
space round the parts 6 of the tubes, and over the tube plate will be under any
circumstances sufficiently large to effect the ends herein set forth.
By the employment of tubes as above described, every tube will serve as a stay
to the tube plates; and thinner tube plates can be used with safety and without
liability of buckling.
With respect to the annular water space at the end of the tube, since in all cases
where high pressure steam is employed, fresh or distilled water only is used, the
liability of their becoming choked or filled or incrusted with deposited matter, will
not exist.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In steam generators of the kind herein referred to, providing substantially as
described, special space round and about the combustion chamber or fire box tube
plate end of the said tubes, and an increased area of tube plate for the water to act
upon by the employment of tubes (or some of the tubes) having the ends thereof
nearest to and secured in said tube plate, of a smaller diameter than the main part
of the tube.
2. The herein described steam generator heating tube, that is to say, a tube of
differential diameters at different parts, the greater or main part being of the
greater diameter and the remainder of a smaller diameter; substantially as and for
the purposes described.

page_text: 3. A steam generator heating tube having the characteristics referred to in the
next preceding claim, and a shoulder (such as f) whereby longitudinal expansion
and contraction is afforded when fixed in the tube plates of a steam generator.
4. In steam generator heating tubes, the construction of the ends which are
secured in the combustion chamber or fire-box tube plate as herein described, that
is to say, constructing such ends in such a manner that an annular space for the
entrance and circulation of water is provided round the greater part of the tube
end which lies between the faces or surfaces of such plate; substantially as and for
the purposes described.
5. The construction of tubes particularly as set forth with reference to
Figures 1, 2, and 3 of the drawings respectively.
Dated this 23rd day of September 1893.
CHEESBROUGH & ROYSTON, Fels. Chart. Inst. P.A.,
15, Water Street, Liverpool, Applicant's Patent Agents.