IMPROVEMENTS IN FURNACES FOR THE PRODUCTION OF SULPHATE OF SODA OR POTASH, APPLICABLE ALSO TO OTHER PURPOSES
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Edmund Knowles Muspratt at the
Office of the Commissioners of Patents on the 4th May 1877.
EDMUND KNOWLES MUSPRATT, of Widnes, in the County of Lancaster, Chemical
Manufacturer. "IMPROVEMENTS IN FURNACES FOR THE PRODUCTION OF SULPHATE
OF SODA OR POTASH, APPLICABLE ALSO TO OTHER PURPOSES."
In the case of furnaces for the production of sulphate of soda or potash, that class
of furnace known as a "blind," "close," or "muffle roaster" has a great disadvan-
tage, namely, that the chimney draught necessary for the combustion of the fuel in
the fire-place produces a lower pressure on the top side of the lower arch of the fur-
nace than that on the under side of the same arch, thereby drawing from the muffle
a portion of the hydrochloric acid gas evolved by the sulphate in process of roasting
on the bed of the muffle, through the brickwork of the arch, and thence to the
chimney.
My Invention has for its principal object the prevention of this escape of gas, and
to effect which I apply a mechanical apparatus for forcing the air necessary for the
combustion of the fuel through the fire, at a pressure exceeding that on the under-
side of the lower arch of the furnace; this pressure, by a judicious closing of the
damper in the chimney flue, is maintained upon the upper side of the lower arch of
the furnace, the effect being to force back rather than draw through the hydro-
chloric acid gas.
The other advantages of my Invention are that I substitute for the comparatively
unmanageable method of producing a draught by a tall chimney a more convenient
and effectual way of regulating the supply of air to the fire for the combustion of
the fuel, thereby effecting a more perfect combustion and a consequent saving of
fuel; and further, an almost entire absence of smoke from the chimney.
Having thus enumerated the objects of my Invention, I will now proceed to
describe the method of carrying it into effect.
The mechanical apparatus for forcing air into the fire-place may consist of the
most approved form of air compressor now known, such as a steam jet or jets, with
single or compound nozzles, or I may use a fan, or any other form of rotary blower,
such as Root's, or others of a similar kind, or I may employ an air pump, or any
other approved apparatus for forcing air.
The air when compressed I convey in a channel made of any suitable material
from the compressor to a closed chamber beneath the bars of the furnace, the air
Price 2d1

page_text: then ascends through the fuel by the force behind it, and exerts its pressure upon
the top side of the lower arch of the muffle in the manner aforesaid.
I do not,
however, allow the whole of the compressed air to pass through the fuel, as the
resistance of the bank of fuel to the air is so great that a sufficient quantity of air
will not pass through it quickly enough to effect a perfect combustion, the analysis
of the products of combustion exhibiting an excess of carbonic oxide when the
whole of the air is made to pass through the fuel.
To supply a sufficient quantity of oxygen to reduce all excess of carbonic oxide
formed to carbonic acid, I construct at the back, the front, or the sides of the furnace
a bye-flue or flues rising from the air channel underneath the furnace bars, and ter-
minating in a combustion chamber over the furnace, part of the compressed air is
forced through this bye-flue or flues, and mixes with the gases from the fuel, and
completes as nearly as possible the combustion of the same. To regulate the quantity
of air passing up the bye-flue or flues, I insert therein a valve or valves which can
be opened or closed at pleasure by the furnace man. The air in passing through
these bye-flues (which by preference I build in the walls of the furnace) has the
further advantage of becoming heated by the heat of the walls of the furnace.
Having thus described the objects and advantages of my Invention, and the
method of carrying the same into practice, I will summarise the applications of the
principles of my Invention as follows:-
First. The application of a mechanical blower, or air compressing apparatus of
any form to furnaces used for making sulphate of soda or potash, and the method as
herein-before described of perfecting, as nearly as possible, the combustion of the
gases by the air conveyed through the bye-flue or flues.
Second. The application of a bye-flue or flues, as herein-before described, to any
other form of furnace to which a mechanical blower may have been previously
applied, such as black ash furnaces, caustic pot or pan furnaces, steam boiler
furnaces, or any other form of furnace used in a chemical works.