AN IMPROVED METHOD OF HEATING IN CHEMICAL AND MANUFACTURING OPERATIONS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Alexander Melville Clark at the
Office of the Commissioners of Patents on the 10th March 1882. A com-
munication from abroad by Paul Depoully and Ernest Depoully both of Paris,
France
ALEXANDER MELVILLE CLARK of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "AN IMPROVED METHOD OF HEATING IN CHEMICAL
AND MANUFACTURING OPERATIONS" [A communication from abroad by Paul
Depoully and Ernest Depoully both of Paris, France]
This Invention relates to an improved method of heating for chemical and
manufacturing purposes and has for its object to provide an economical and
efficient substitute for the baths of oil, paraffin, air &c now used whereby apparatus
may, without sacrificing the advantages of such baths, be heated during a long
period to a constant temperature higher than attainable by such baths, 200°, 300°,
500° Centigrade or more; whereby to avoid burning and decompositions caused by
a naked fire, and the objections due to deposits or incrustation caused by over-
heating the bottom of such apparatus; and whereby to enable the operations of
distillation and sublimation to be effected without condensation of the volatile
portions in the alembic. In short the Invention is designed to enable chemical
and other operations which necessitate high temperatures to be effected without
the direct action of the fire and at constant temperatures.
This method of heating consists in wholly or partly enclosing the apparatus
containing the matters to be submitted to the action of heat in an envelope or
jacket to which steam is supplied, this jacket being heated by a fire. It is
preferred to heat the jacket at the side in order to avoid sudden heatings.
The jacket is furnished with, a safety valve but it should work either with no
pressure or under very low pressure. The steam, expanded or not, circulates in a
continuous manner through the envelope or jacket so as to heat the apparatus
uniformly, and escapes by an outlet cock.
By this means high temperatures may be attained and the heat regulated to any
desired degree-100°, 140°, 200°, 300°, 500° or higher-the too intense action of
the fire being modified or regulated as desired by opening more or less the inlet or
outlet cocks for the steam,

page_text: The consumption of fuel and steam is very small. The heat which the steam
loses in heating the apparatus and its contents, and in volalitilizing those matters
that are to be volatilized is constantly made up to it by the heated envelope.
From this it will be seen that it is not a mere employment of superheated steam,
but a steam jacket or bath which is superheated in a continuous manner. Steam,
superheated in any special separate apparatus, may be employed instead of ordinary
steam without departing from the Invention, but merely passing superheated steam
through the jacket without applying heat to the latter will not however effect the
desired result for to attain a high temperature in this manner would necessitate the
expenditure of an enormous quantity of steam, and even then the loss of heat
through the external walls of the jacket would perhaps prevent the desired
result.
An essential feature of this Invention is, therefore, a steam bath or jacket
wherein the steam is kept continually superheated in the jacket itself.
The following are some of the operations in which this system of heating may be
employed. In distilling oils, petroleum, coal oils hydrocarbons, aniline, phenols &c.
An alembic is filled with the product to be distilled. This alembic is isolated and
completely enclosed by a steam tight envelope which receives the steam and is
heated to the desired temperature. The distillation is effected without condensation
in the alembic, the upper part being at the same temperature as the lower part,
and the residue of the distillation will not be carbonized.
In distillations which require the employment of superheated steam to carry
over the products to be distilled (fatty acids phenols &c) the advantages of this
method are obvious. If desired ordinary steam may be introduced into the heated
alembic, as it will become superheated in the alembic itself.
The same kind of apparatus is applicable for subliming the most delicate products;
for the manufacture of aniline colors; for the combinations of sulphuric acid with
hydrocarbons, phenols, organic alkalies, artificial colors &c; also for effecting fusions
by means of potash or soda which are of such importance in the manufacture of
artificial colors. In the latter case the matters may be placed in an open heater
furnished with a stirrer and surrounded by the bath of steam at the desired
temperature. The steam will circulate through the entire apparatus both in the
heater and envelope and all portions of the matters will be equally heated.
The principle of the invention will remain the same if the interior vessel be in
direct communication with the steam of the jacket it being none the less protected
from all direct action of the fire and the steam is at too high a temperature to be
injurious to the action. On the contrary the formation of a crust will be prevented.
If the operation necessitates the use of a digester, the digester will be immersed in
the steam.
Finally the invention is also applicable to stoves for drying and for operations at
a high temperature; for heating earthenware, and glass vessels, and carboys &c to
high temperatures without fear of breakage; for distilling mineral acids for
obtaining pure acids and for concentrating sulphuric acids; and for the torrefaction
of organic alimentary and other matters. These instances of the various applications
are given as examples to exemplify the results obtained by the system of heating
of which the different possible applications are very numerous.