Process for Purifying Chlorine Gas.
Year: 1896

page_text: Date of Application, 5th May, 1895-Accepted, 13th June, 1806
COMPLETE SPECIFICATION.
Process for Purifying Chlorine Gas.
I, PETER JENSEN, of 77 Chancery Lane, London, Chartered Patent Agent, do
hereby declare the nature of this invention, a communication to me from abroad
by Diderik Cappelen and Hans Cappelen, of Gjemso Kloster, near Skien, Norway,
Manufacturers, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
In the electrolysis of alkaline chloride solutions for obtaining chlorine gas for
bleaching purposes a serious difficulty arises which reduces the economical yield of
the process to a not inconsiderable degree namely that the chlorine gas contains
impurities viz. other gases owing to secondary reactions in the bath, carbon
dioxide being especially objectionable.
The present invention consists in a process for treating the chlorine
gas whereby
it is freed from most of the carbon dioxide. Ordinarily the chlorine gas is led
directly from the electrolysis vessels to the lime chambers in order to be absorbed
by the lime. But the carbon dioxide which accompanies the chlorine gas in rather
large quantities has so great an affinity to the lime that it greatly hinders the
desired chlorinating of the lime.
Now it has been experimentally found that most of the carbon dioxide can be
removed by letting the chlorine gas from the electrolysis vessels pass through lime
milk. For the dioxide is found to be almost exclusively absorbed by the lime,
while the chlorine gas is partly absorbed by the water and partly escapes from it
in a purified condition. The absorption vessels used for this purpose are provided
with pipe devices and work under pressure, while the impure gas is pumped
in somewhat below the liquid level, and the escaping purified chlorine gas is led
away through pipes provided with regulating valves. The amount of lime in the
lime milk is steadily kept up by steadily taking account by analysis of the amount
of carbon dioxide in the escaping chlorine gas.
The loss of chlorine proves to be very small, the lime residuum at the bottom of
the absorbers seldom containing more than a per cent. of chlorine. The purified
chlorine gas on the other hand contains very little carbon dioxide as it can be
reduced to 38 per cent., as against many per cent. in the unpurified chlorine gas.
It thus becomes possible to obtain for the chloride of lime chambers a chlorine
gas almost free from carbon dioxide, and a bye product five per cent. of chlorine
water which can be applied partly in paper factories and partly in breweries the
residual carbonate of lime has a value as manure.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondents, I declare that what I claim is,
A process for removal of the carbon dioxide from the chlorine gas obtained by
electrolysis of alkaline chloride, consisting in passing the gas through lime milk,
whereby the carbon dioxide is taken up by the lime and the chlorine gas is partly
absorbed by the water and partly escapes in a purified condition.
Dated this 5th day of May 1896
JENSEN & SON,
77 Chancery Lane, London, W.C., Patent Agents.