Improved Means for Preventing Back Draught in Pyrites Furnaces.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improved Means for Preventing Back Draught in Pyrites Furnaces.
I, CILARLES DENTON ABEL, of Birkbeck Bank Chambers, Southampton Buildings,
Chancery Lane, in the County of London, Consulting Engineer and Chartered
Patent Agent, do hereby declare the nature of this invention (as communicated to
me from abroad by Stassfurter Chemische Fabrik vormals Vorster & Grüneberg
Actien Gesellschaft, of Stassfurt, in the Empire of Germany, Manufacturers),
to be as follows:-
For preventing the objectionable and deleterious back draught or outward blast
of pyrites furnaces, (which is also the causes of losses) during the charging or the
stoking of the contents of the furnace, that is to say, generally, when the furnace
doors are opened, the following proposals are known.
1. Hasenclever (Zeitschrift der chemischen Industrie 15/12/95 No. 24 p. 494)
connects the air supply channels (which before the charging are closed) with a
cold chimney not connected with any furnace for the production of rarefied
air under the furnace grates, the rarefaction being such as to exactly
counterbalance the outward gas pressure of the furnace, so that furnace
gases are neither blown outward nor are drawn in by the chimney, and thus loss
is avoided.
Irrespective of the difficulty of always maintaining the equilibrium-the force
of the back draught being subject to continual variations these cold chimneys
have the inconvenient property of becoming inoperative just at the time when
they require to be used, so that by this fact they lose their practical value.
It is not possible to employ a chimney that communicates with a furnace and
consequently has a draught, as even with the greatest care it is not possible to
prevent the furnace gases from finding their way into the chimney and thus
becoming lost.
It is also not possible to use injectors for creating a draught because they so
rapidly get out of order through the wear or clogging of the nozzles by furnace
dust; in addition, the loss of furnace gases is not avoided thereby.
2. Dr. Jurisch (Ueber Gefahren der Arbeiter in chemischen Fabriken &c.
Ber'in 1895 Gaertners Verlag) gives as the sole effective means, a strong draught
for the whole furnace system placing the lead chambers more than tiom 5 to
10 metres above the ground, large sectional areas for all connecting pipes, and
working doors as small as possible.
Jurisch states that in England a direct communication during the charging is
effected by means of flues with dampers, between the furnace and the lad
chamber, for preventing back draught (see Hasenclever Chemische Industric).

page_text: The arrangement which forms the subject of the present invention is free from
all the above mentioned disadvantages, and conditions; it requires at least two
separate sets of furnace systenis.
The arrangement is such that on the one hand the draught of the furnace
through air supply channels opening below the grates is entirely cut off during
the charging, that is while the doors are open; on the other hand, when the doors
are closed and the air supply channels are also closed, the draught of the furnace
produces a rarefaction of the air under the furnace grates.
If therefore the closed air supply channels of the one furnace system, whose
charging doors are closed, be connected by means of a flue or conduit pipe with
the closed air supply channels of another system of furnaces with open charging
doors, the system with closed charging doors will draw its air supply through the
open charging doors of the other system, so that the latter, instead of being.
subject to back draught, will have an indraught of air through the open charging
doors.
The proportion of furnace gases which is carried along by this air supply is of
course not lost.
By thus connecting the air supply channels of two or more systems of furnaces
with each other by means of a pipe or channel according to the present invention,
the back draught of the furnaces is entirely prevented, without any loss of furnace
gases and without the risk of air that has not passed through layers of burning
pyrites passing into the system.
Dated this 25th day of June 1898.
Improved Means for Preventing Back Draught in Pyrites Furnaces.
I, CHARLES DENTON ABEL, of Birkbeck Bank Chambers, Southampton Buildings,
Chancery Lane, in the County of London, Consulting Engineer and Chartered
Patent Agent, do hereby declare the nature of this invention (as communicated to
me from abroad by Stassfurter Chemische Fabrik vormals Vorster & Grüneberg
Actien Gesellschaft, of Stassfurt, in the Empire of Germany, Manufacturers),
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 means for preventing back draught or outward blast
in pyrites furnaces when the working doors are opened for charging or stoking the
furnaces, as will be described with reference to the accompanying drawings.
Figure 1 is a sectional plan of a so-called "Belgian furnace with the invention
applied thereto.
Figure 2 is a section on the line a--b of Figure 1.
Figure 3 is a section on the line of Figure 1.
Figure 4 is a sectional plan of a so-called "English" furnace and Figure 5 is a
section on line c-d of Figure 4.
The improvements consist in the connection of the air supply channels of two or
more furnace systems, which are completely separated when working normally, in
such a way that when the charging doors of the one system are open, the air
supply channels of both systems are closed; thus the system with both its air
supply channels and charging doors closed will draw air through the open charg
ing doors of the other system, the air supply channels of which are also closed.
Back draught is in this way prevented.

page_text: The air supply channels of the two or more furnaces or systems of furnaces-
are, so connected therefore, that when the turnaces are in full work each obtains
its necessary air supply independently of the other; it, however the air supply
channels of both furnaces are closed while the charging doors of one furnace are
open, the other furnace draws in air through these open doors, so that no furnace
gases can escape through them into the outside air. The gases sucked in in this
way pass through the furnace with closed doors and are not lost.
The Belgian furnaces shewn in Figures 1, 2 & 3 consist of compartments Fin
which the pyrites is burnt on the grates D beneath which are the air supply
channels C. Each furnace of this system is divided by a partition h
through which is an opening G for communication between the air supply
channels of the two divisions. The air supply channels of the separate furnaces
are connected by the conduit A, and each channel can be closed by a damper I
(Figure 3).
The working is as follows:-When the working door E of the furnace shown
on the left hand of Figure 2 is to be opened the air channels C of both furnace
systems are closed and the working doors of the right hand furnace system are
also kept shut.
Under these circumstances the right hand furnace draws air and other gases
through the conduit A, so that air enters the open working door E of the left
hand furnace from outside the furnace, passes through the compartment F, the
grate D, the opening G and the conduit A into the air channels of the right hand
furnace.
The chimney H has no damper.
English pyrites furnaces have a so-called air supply channel for each furnace
chamber of a furnace system. In the Maletra furnaces there is a common air
supply channel to a number of furnace chambers placed vertically above ong
another.
Furnaces of the English" kind are shewn in Figures 4 & 5. F are the separate
furnace chambers, E the charging doors, D the grates below which are firstly
dampers K through which, during normal working, air is directly admitted from
the atmosphere, and secondly dampers J communicating with the channels C
which are connected together by the conduit A that connects the two systems.
These dampers J are closed during the normal working. There is no damper
in the chimney H. The working is as follows: -The working door E of one of
the compartments of the left hand system having to be opened, the damper J of
this compartment is opened as well
as that of one or other of the
chambers of the right hand system while the dampers K of the direct
air supply to these compartments are closed; the desired communication
between the two systems for the prevention of back draught is thus established
through channels C and conduit A.
A draught gauge inserted into this conduit shows
(1), no draught when the air supply channels of both systems are open and the
charging doors are closed, for then each system draws its air from its own main
channel;
(2), the draught of the system having the stronger draught when both the air
supply channels and charging doors of both systems are closed; and
(3), the draught of the system with closed charging doors when the air supply
channels of both systems are closed and a charging door of one system is open.
Such a draught gauge (a Jensens "flutometer may be used since air alone, not
furnace gases, will come in contact with the instrument) forms a valuable aid to
regulating the working of the furnaces.
Having now particularly described and ascertained the nature of this
invention, and in what manner the same is to be performed, I declare that what
I claim is: :-
Means for preventing back draught in pyrites furnaces consisting in the pro-

page_text: vision of a connecting channel between the air supply channels of two or more
separate systems of furnaces, whose furnace chambers have their working doors and
the air inlets provided with closing devices, substantially as described.
ABEL & IMRAY,
Agents for the Applicant.