IMPROVE- MENTS IN ABSORBING THE SULPHUROUS GASES GIVEN OFF BY FURNACES, CALCINING KILNS AND OVENS
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Farnham Maxwell Lyte at the
Office of the Commissioners of Patents on the 10th December 1881.
FARNHAM MAXWELL LYTE of Putney in the County of Surrey.
"IMPROVE-
MENTS IN ABSORBING THE SULPHUROUS GASES GIVEN OFF BY FURNACES,
CALCINING KILNS AND OVENS."
My Invention consists of improvements in the process for which an application
for Letters Patent was made by Charles Denton Abel, No. 3443-1881 which relates
to the absorption and utilisation of the sulphurous acid contained in the gases froin
furnaces and calcining kilns, and my Invention has for its object to employ certain
metallic oxides more readily available in this country than the hydrates of magnesium
or aluminium employed in the said process.
The process referred to consists in the employment of the hydrates of magnesium
or aluminium suitably disposed in the flues of the furnaces or kilns through which
the gases pass, and maintained at a moderate temperature, said oxides absorbing
the sulphurous acid contained in the gases with great energy, forming sulphites,
which on being further heated become resolved back again into sulphurous acid
which volatilises, the magnesia or alumina meanwhile remaining fixed.
In place of the above oxides I employ the hydrate of zinc oxide (such as that
obtained in carrying out the process for which Letters Patent were granted to me
No. 633 of 1877) or one of the hydrates of the oxides of iron. These oxides may
be placed in trays or on hurdles or perforated shelves within the flues of the furnaces
or kilns, or in chambers built in or connected with the flues, or may be mixed with
water to form a cream and beaten up or sprayed into the atmosphere of the flue,
or run in fine streams in such manner as to bring them into intimate contact with
the gases as they pass, thereby promoting the more complete absorption of the.
sulphurous acid. In order to facilitate the more complete absorption, it is
advantageous that the gases should be reduced to a temperature not exceeding
about 212° F. This may be conveniently done by spraying water into the gases
prior to or at the moment of their contact with the metallic hydrate.
In this manner sulphites of the said metals are produced, and in the case of the
higher oxides of iron, some of the said sulphites become converted into sulphate of

page_text: ferrous oxide. In all cases some sulphates may become produced together with the
sulphites through the action of any free oxygen that may be present.
The salts of the sulphur acids thus formed may be collected by any of the usual
methods such as filtration or evaporation-and on being heated to a higher
temperature than that at which they were absorbed -
-a low red heat for instance-
sulphurous acid is again disengaged and may be collected and industrially
utilised.
For more completely promoting the disengagement and regeneration of the
sulphurous acid, some pounded charcoal or other reducing agent may be mixed with
the sulphites previous to the heating. The reducing agent may be mixed with the
oxide either previous or subsequent to its exposure to the current of the sulphurous
gases.
In lieu of the metallic hydrates above mentioned, the carbonates of the same
metals may be employed, or other metallic hydrates or carbonates such as those
of calcium, copper, nickel, &c., might be employed, but not generally with so much
advantage.