IMPROVEMENTS IN THE CONSTRUCTION OF BOILERS, FURNACES, AND FLUES
Year: 1858

page_text: PROVISIONAL SPECIFICATION left by George Heppell at the Office of
the Commissioners of Patents, with his Petition, on the 6th October
1858.
I, GEORGE HEPPELL, of Newcastle-on-Tyne, Engineer, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF
BOILERS, FURNACES, AND FLUES," to be as follows, that is to say:―
Instead of using the ordinary construction and arrangement of boilers, I
propose to have one boiler which I call the steam generating boiler, and
another completely enveloping or encasing the former, which. I call the heating
boiler; my arrangement is therefore to have the inner or steam generating
boiler heated by contact with the water and steam in the outer boiler, which
in its turn is heated by means of peculiarly arranged furnaces hereinafter
described.
I propose to keep the steam in the outer boiler at a low pressure, while that
in the inner will be kept at a much higher one. The outer boiler I. propose
to supply with water in the usual manner, the inner one to be fed from an
iron chest or reservoir charged by means of a small pump, similar to a
hydraulic ram, so that the pressure upon the water in the chest shall be a few
pounds more than that at which the steam is kept at in the said boiler. Upon
the said water chest I place a safety valve, so that the steam in the boiler can
never exceed the pressure on the valve without indicating the same.
. I propose also to carry off any electric fluid developed in the inner boiler
from the superheated steam by means of an insulated conductor of the usual.

page_text: kind, one extremity of which is inserted into the inner boiler, and the other
passes into the earth. Furthermore, in order to guard against any danger
from a vacuum or partial vacuum being formed in the inner boiler, I propose
to insert within it a collapsing valve, one side of which is open to the external
atmosphere, the other to the pressure of the steam in the inner boiler, so that
should the pressure on the outside of the boiler become greater than that in
the interior, the air acting upon the collapsing valve will force it inwards, and
by means of certain mechanical arrangements it will be retained open until an
equilibrium of pressure is obtained.
The next part of my Invention relates to the means for heating the boilers,
that is to say, to the arrangement and construction of the furnaces and flues.
I propose to have three separate compartments for furnaces, each, however,
communicating with the others; namely, a centre furnace and two sides ones.
The side furnaces are, as their name implies, situated at the sides of the end of
the boiler, and into these is put the coal or fuel to be burnt. The charging
doors may either be in the front or at the sides; the bars of these lie at an
angle transversely to the longitudinal axis of the boiler, and sloping downwards
and towards the central furnace; at the lower extremity of the bars there is
an opening into the central furnace through the partition which separates the
central compartment from the sides ones, and through this opening the incan-
descent fuel from the side furnaces is supplied to the central furnace. This latter
has its bars horizontal, and below the level of the lowest side of the side furnaces;
the face or end in which the door or opening is usually placed is built up by a
wall or iron plate, leaving a small drift space between it and the mouth of the
furnace, which latter has a series of iron bars stretching across for a purpose
herein after mentioned.
From the ends of each of the furnaces runs a flue or tube, either through
the water space of the outer boiler, or, where this form of boiler is not used,
underneath or along the sides of the boiler, that from the central furnace
running into the chimney shaft, while those from the side furnaces, after reaching
the end of the boiler, bend each into a return drift or flue, which traverses
either underneath or by the side of the boiler back to the front end, and dis-
charges into the space between the front wall and the centre compartment or
furnace.
From this arrangement it will be seen that the central furnace, being solely
fed with the partly consumed fuel from the side furnaces, will always be in a
state of perfect combustion, and any smoke which is generated will be in the
side furnaces, but as the flues from these return and discharge their smoke
and gases into the central furnace through the heated bars in front, they will

page_text: be perfectly consumed in passing through this furnace, and the residuum of
heated air and gas will pass from it direct through the central tube or flue into
the chimney shaft. Atmospheric spaces will be arranged in the most suitable
places to supply the requisite amount of air for combustion, both to the side
and central furnaces.
Retaining the general principles of construction above described, I apply
the same arrangement modified to suit the particular requirements of the case
to all kinds of boilers, whether stationery, marine, or locomotive.