Improvements in Furnaces for Steam Generators and other Evaporating Apparatus.
Year: 1895

page_text: Date of Application, 19th Jan., 1895-Accepted, 24th Aug., 1895
COMPLETE SPECIFICATION.
Improvements in Furnaces for Steam Generators and other
Evaporating Apparatus.
I, CHRISTIAN ALBERT JENSEN of 77 Chancery Lane, London Chartered
Patent Agent do hereby declare the nature of this invention a communication to
me from abroad by Rudolf Müller of Myrens Værksted Christiania in the
Kingdom of Norway Mechanical Engineer 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 furnaces for steam boilers and other evaporating
apparatus and has for its object to improve the construction of such furnaces so as
to make them more economical and to obtain a smokeless combustion. This new
furnace may be adopted for all kinds of boilers and may in some cases be
constructed so as to be placed in front of the boiler instead of underneath the
same, though the latter arrangement is preferable.
A special feature in this invention is the arrangement of one or more waterboxes
across in the furnace, forming the back walls of coal magazines, in which the
combustion takes place at the bottom, and so that the coals are gradually being
heated. The invention also involves the combination of two grates or separate
fireplaces one above the other, from which the gases are led to a common
combustion chamber or flue.
One mode of constructing this new furnace is shown in the accompanying
drawings in which a furnace suitable for a watertube boiler is shown in Fig. 1 in
longitudinal section and in Fig. 2 partly in cross section and partly in front view.
Fig. 3 shows the waterbox system looking from behind (partly sectioned or broken
away) and Fig. 4, 5 and 6 are detail views.
A represents a wrought iron welded waterbox extending across the furnace; B is
a similar waterbox, forming the back wall in the lower fireplace and extending
down to the grate bars L. being provided with three arch-shaped openings K
through which the fire gases may escape. Both of these waterboxes communicate
by means of a number of pipes F and G with two other waterboxes C and D
arranged in the front wall of the boiler. The pipes F form a watertube-grate for
the upper fire place and the pipes G form a roof over the coal magazine below.
The waterboxes C and D (see Fig. 2) communicate with each other through the
short pipes I and also communicate with four vertical waterboxes E, E, E¹, E¹,
from which four rows of waterpipes H, H, H', H', extend to the waterbox B and
divide the lower fire place or magazine in three compartments. The water
boxes A and B communicate with each other through the lateral pipes J. From
the lower end of the pipe J extends a pipe J¹ to the back part of the waterspace
of the boiler and from the top of the waterbox A extends a pipe J to the front
part of the steam drum. B' is a firebridge formed by a watertube, the same being
on both sides of the fireroom fitted into pockets B₁ projecting from the rear wall
of the water box B.
The lower fireplace is provided with a grate L which forms the bottom in a fuel
magazine enclosed between the water-box B, the movable grate M and the water-
tube walls H and G. In this magazine the combustion_chiefly takes place near
the grate, so that the flame escapes through the openings K ; air is supplied partly
through the stored coal in the magazine, partly through the grates M and L and
partly through the movable grate N arranged behind the firebridge. The supply

page_text: of air at this place may be regulated by means of the door S and rod T. The
movable grate N may be rocked by means of the rod R connected with the arm P
on the spindle O of the grate.
The upper fire place is as already mentioned, provided with a watertube
grate F; the same being only short the pipes are not liable to become crooked and
thereby leaky which is a usual drawback with watertube grates. In order that
these grates may work advantageously the openings between the pipes have to be
somewhat wide from which reason coals not completely burnt are liable to drop
down into the ashpit and thereby get lost for the combustion; in this construction
this circumstance is of no importance because coals that drop down remain on the
grate N or on G and may continue burning till no combustible matter is left.
Air is supplied to the upper furnace partly through the fire door (above the
coals) and partly beneath the grate through the opening between the waterboxes C
and D.
The radiating heat from the fuel on the upper grate is taken up by the lower
row of watertubes of the boiler. The plate forms the roof above this upper
fireroom.
The vertical watertube-walls H are constructed as shown in Fig. 4; triangular
cast iron pieces. U being. placed between the pipes. Fig. 5 and 6. show the
construction of the horizontal waterspace G, between the pipes of which there are
laid cast iron pieces V held together by means of screws W.
The advantages gained by this new system of furnace consist mainly in the
following points
1) The combustion may be very accurately regulated.
2) The combustion is never disturbed by cold streams of air.
3) The cold coals supplied to the magazine do not come in contact with the
glowing and burning coals on the grate but are gradually heated.
4) The fire becomes very intense because the coals give off their gases to the air
passing down through the same, so that the gases and the air are completely mixed
when ignition takes place. Parts of the coals, which remain as slag in other
furnace are therefore completely consumed in this improved furnace.
5) The arrangement of two grates above each other shortens the length of grate
surface and the bringing together two separate flames in a common combustion flue.
or chamber ensures a very complete combustion.
6) No loss of heat by radiation because of the complete enclosure of the fireplace
by water spaces.
7) As there is no smoke the initial temperature of the combustion gases is
higher and the final temperature lower than by common furnaces.
8) Compared with other furnaces of novel construction where magazines for the
coals are made use of this new construction has the advantage that the fire may
easily be stoked and thereby freshened, for which purpose usual fire tools may be
inserted through the inclined grate M. This is advantageous: for most of the
boilers used on land for industrial purposes, it being often required to force the fire
for obtaining for a short time more steam. In other magazine furnaces. however
the layer of coal is so high, that stoking is not possible.
If the furnace is to be used for a boiler where it has to be placed in front of
the same it may be enclosed in brickwork. In some cases the upper fire place may
be left out.
The cleaning out of the waterboxes and water tubes takes place through
mudhole doors shown in the drawing in several suitable places.
Having now particularly described and ascertained the nature of the said inven-
tion as communicated to me by my foreign correspondent and in what manner the
same is to be performed I declare that what I claim is :
1. In a furnace for steam generators and other evaporating apparatus the
combination of an upper and a lower firegrate with a common combustion
chamber or flue, the lower fire grate being arranged at the bottom of a coal

page_text: magazine, separated from the upper fire place by means of a vertical water box
extending right across the fireplace and a water space above the same horizontal or
nearly so said vertical waterbox being provided with openings near the grate
through which the fire gases from the magazine may escape, substantially as
described.
2. The combination in a furnace for steam generators and other evaporating
apparatus with a lower firegrate and a fuel magazine above the same of an upper
fire-grate, said upper firegrate being constructed as water tube grate, the pipes of
which connect a waterspace in the front of the boiler with an upper waterbox
placed across the fireplace and between which and the waterbox mentioned in
Claim 1 the flame from the watertube grate passes uniting below the upper water
box with the flame from the lower firegrate.
3. In a furnace for steam generators and other evaporating apparatus the
combination with a transverse waterbox, B, of longitudinal waterspaces, H, formed
by pipes and dividing the coal magazine in several compartiments, which connect
with the common combustion chamber through openings K, in the rear wall (B)
and of a waterpipe, B', serving as firebridge.
4. In a furnace of the system described the arrangement of a rocking grate (N)
behind the coal magazine for the purposes specified.
5. In a furnace of the system described the construction of the watertube walls
as described with reference to Figs. 4, 5 and 6.
6. The furnace described and shown.
with day of January 1895.
JENSEN & SON,
77 Chancery Lane, London, W.C., Patent Agents.