Improvements in Water-tube Boilers.
Year: 1897

page_text: Date of Application, 20th Feb., 1897-Accepted, 21st Aug., 1897
COMPLETE SPECIFICATION.
Improvements in Water-tube Boilers.
We, NELSON FOLEY, of Isola di Gaiola, Posillipo, and FREDERICK FURSE, of Villa
Schlaepfer, Capodimonte, both in Naples, in the Kingdom of Italy, Engineers,
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 steam generators of the water-tube type, and is specially,
though not exclusively, applicable in boilers intended to be worked with forced
draught, and commonly known as "express boilers."
In the accompanying drawings, Fig. 1 represents, in part longitudinal section and
side elevation, a water-tube boiler embodying the present improvements; Fig. 2 being
a corresponding part transverse section and front elevation. Figs. 3 and 4 are views
similar to Fig. 2 showing alternative methods of construction.
Referring to Figs. 1 and 2, a water-tube boiler constructed according to our
invention comprises a central steam receiver A, which may be of circular or of other
cross section, and series of water-chambers B B, the latter being disposed one above
another on each side of the grate C, (which is made in any usual manner of any
desired style, shape and size,) and parallel with the receiver. The water-chambers`
may be held together at each end by means of angle iron or by other systems of
fixing. In the drawing, four water-chambers B are shown on each side of the grate,
but the number may be varied according to the heating surface and the number of
tubes required. The water-chambers are preferably of such a size that they can be
readily formed by stamping out of boiler-plate, or they may be constructed of cast
steel or otherwise, in each case being so limited in size that the doors generally will
not necessitate the use of staying devices. Each water-chamber B pertaining to its
respective side of the generator is connected to the corresponding side of the
receiver A by numerous tubes D D preferably made of weldless steel. In the
example shown in the drawing, the tubes D are straight, with the exception of
the lowest set which connects the bottom pair of water-chambers with the receiver.
These sets being subjected to the highest temperatures, the tubes comprising the
same are slightly curved, with a view to ensuring expansion in the one direction, and
thereby to avoid the closing of the intervening spaces, which might otherwise occur,
and thereby prevent perfect combustion. But, if desired, these tubes may be straight;
or the tubes of the upper nests may be curved. The number of rows of tubes D will
also vary according to their diameter and number. Each water-chamber is provided
with a cover plate or door b, which can be readily removed for expanding and
cleaning the interior of the tubes D, the said doors being similarly made by stamping
them out of boiler-plate, or they may be otherwise produced. In order to maintain
the weight and dimensions of the doors within certain limits, convenient for
overhauling, each set of water-chambers may be divided into two or more lengths,
but in the case of short boilers, this may not be considered necessary.
A suitable casing I encloses or surrounds the steam generator. Between the
second and third water-chambers and above the top water-chamber, on each side, an
open space is left, provided with a removable door E, for visiting and cleaning the
outside of the tubes and also for removing or putting in new tubes, when required;

page_text: doors FF being fitted at the front and rear of the boiler through which new tubes
can be introduced and old ones removed, in case bunkers or other obstructions should
prevent these operations being performed directly through the doors b. If required, the
number of the doors E and F may be augmented and their position varied according
to the number and position of the water-chambers. Besides the above mentioned
doors E and F, the casing is provided with any necessary doors for cleaning, with
dampers, and with the other usual appliances and devices. The products of
combustion are led across and round and between the tubes D to in appropriate flue
in any convenient and suitable manner. Any ordinary and suitable appliances and
devices can be provided to regulate and utilize to the best advantage the heat of
the furnace and to apply thereto forced or induced draught or the like.
To ensure a good circulation of the water, one or both ends of each water-chamber
is connected to the receiver A by means of a large tube or tubes G, same serving
to return the water from the receiver A to its or their respective water-chamber or
water-chambers B, and to support the receiver. These tubes may be placed inside
or outside the combustion chamber. The normal water level may be higher or lower
than that indicated in the drawing, as the case may be; care being taken that the
ends of the tubes G in the receiver are always well covered by water.
To provide
for the return tubes nearest to the water-level being always covered by water, even
in heavy seas when a ship is rolling or pitching, a mouth piece is applied over
them, as shown in dotted lines in Fig. 2, whereby a certain quantity of water is
enclosed and the tubes always receive their supply from a low level.
In the alternative designs, Figs. 3 and 4, the general principle is the same as in
the construction above described. They are specially applicable in cases where
weight is not an object of much importance. Attached to the under side of the
receiver A is a smaller receiver or water-drum H of any convenient shape and size,
to which the return tubes G of each water-chamber B are led. This water-drum
presents the advantage of a lower water-level, with the result that a greater steam
space is obtained as well as a freer discharge of steam. Moreover, the quantity of
water being concentrated or kept to the centre of the boiler, the water-level is less
affected by the rolling of the ship and there is less risk of the water in the boiler
running short.
In Fig. 3, the water-chambers are shown similar in shape to those in Figs. 1 and 2,
while in Fig. 4 they are slightly different, the water-chambers being each composed
of a flat tube plate with a curved door. In the two latter constructions, we have
illustrated, as an example, a boiler having three water-chambers on each side; the
number of doors F for removing or cleaning the outside of the tubes being
correspondingly reduced. The steam generated in any of these apparatus may be
taken for use directly from the upper part of the receiver A, and water may be
introduced into the lower part thereof or into the water-drum H or otherwise in any
convenient and usual manner, by and through any ordinary and suitable means and
appliances, and at any appropriate and customary position or positions. The receiver
may be furnished with doors, manholes or the like, same being fitted in any suitable
and convenient manner, whereby access to the interior is afforded.
Water-tube boilers constructed as herein described present the following
advantages:-
(a.) Owing to the inclination at which the heating tubes are placed, considerable
air pressure may be employed and the evaporation will be rapid.
(b.) There is ample space over the grate to ensure the combustion of coal without
premature chilling; besides which the space between each nest of tubes enables the
final combustion to develop more easily.
(c.) The heating tubes being readily accessible at both their ends, and the doors
being few and small, the operations of visiting, cleaning, expanding and removing
can be accomplished without difficulty.
(d.) No stays are required in the water spaces and the whole boiler, with the
exception of the tubes, may be constructed of steel plates, and there are no joints
exposed to the action of the fire.

page_text: (e.) In relation to the space occupied, a considerable amount of grate and heating
surface is obtained; the heating surface being of a very efficient nature, owing to the
zig-zag form in which the rows of tubes are arranged.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we claim :-
1. A water-tube boiler constructed substantially as described with reference to
Figs. 1 and 2 of the accompanying drawings, and comprising a receiver A, two series
of water-chambers, such as B, severally connected with the receiver inside the
combustion chamber by means of heating tubes D, which may be straight or bent,
and also by means of large return-tubes G, disposed either inside or outside the
combustion chamber and serving also to support the receiver.
2. In a water-tube boiler of the general character herein referred to, the
combination, with the receiver A and return-tubes Gr, of the shield or mouth piece g,
substantially as and for the purpose specified.
3. A water-tube boiler constructed substantially as described with reference to
Fig. 3 or to Fig. 4 of the accompanying drawings, and comprising a receiver A, two
series of water-chambers, such as B, severally connected with the receiver inside the
combustion chamber by means of heating tubes D, which may be straight or bent, a
water-druin H in communication with the receiver and, by means of large return-
tubes G, with the several water-chambers, the said return-tubes being arranged
either inside or outside the combustion-chamber.
4. In a water-tube boiler of the general character herein referred to, two series of
water-chambers, respectively arranged on opposite sides of the receiver A, the several
water-chambers B of each series, whether formed in one or more lengths, being
placed one above the other and parallel with the receiver A.
Dated this 20th day of February 1697.
For the Applicants,
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Chartered Patent Agent.