IMPROVEMENTS IN THE MANUFACTURE OF GAS AND IN THE APPARATUS EMPLOYED THEREIN.
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by John Henry Johnson at the Office of
the Commissioners Patents on the 8th September 1881. A. communication.
from abroad by François Coignet, of Paris, in the Republic of France.
JOHN HENRY JOENSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN THE MANUFACTURE OF GAS AND IN THE
APPARATUS EMPLOYED THEREIN.' A .communication from abroad by François
Coignet, of Paris, in the Republic of France.
This Invention relates to an improved process and apparatus for the manufacture
of gas for illuminating and heating purposes from schist or petroleum oils, or
vegetable or animal oils or fats, or any suitable carburets.
In carrying out the said Invention, two vertical retorts of cast iron or cylinders
or other suitable material are arranged concentrically one within the other; these
retorts are placed in a furnace working by preference with a reversed or return
flame so as to admit of the temperature being suitably regulated.
The retorts or cylinders are so arranged that a clear space of, say, about one inch,
is provided between their adjacent surfaces and forms an annular chamber
surrounding the internal cylinder. This cylinder, which is open at its upper end
but closed at its lower extremity, is of approximately the same height as the
external cylinder, and does not rest upon the bottom or lower end of the latter,
being suspended at its upper párt by a flange or enlargement bearing upon
corresponding lugs or projections cast on the interior of the outer cylinder. The
internal cylinder becomes heated. to practically the same degree as the outer
cylinder by which it is supported. The outer cylinder may be provided with
external ribs or projections, and is closed at its upper extremity by a suitable cover
provided with means for introducing the oil or materials to be treated. The gases
produced in the apparatus escape through a suitable gas escape pipe communicating
with the lower part of the outer cylinder. These retorts or cylinders are set in
the masonry of a furnace, the fire place or combustion chamber of which is arranged
preferably below the retorts, the products of combustion being conducted through
suitable places to a chamber above where the flame circulates about the outer
cylinder and whence the smoke escapes through downcast flues to the chimney.
This apparatus operates in the following manner, viz. :-Heavy oil for example,

page_text: supplied at the upper part of the outer cylinder in a thin and continuous stream,
or drop by drop, by means of suitable distributing apparatus is caused to fall to the
bottom of the inner cylinder which is heated to redness or a temperature of from
about, seven hundred and fifty to eight hundred degrees centigrade. At this
temperature the oil is volatilized and decomposed; the gases and vapours thus
produced first rise in the internal cylinder and then descend the narrow annular
space between the two cylinders. The sides of the cylinders being uniformly
heated as hereinbefore described to from about seven hundred and fifty to eight
hundred degrees, and the gas being thus spread out and detained for a considerable
period in intimate contact with the heated surfaces of the cylinders, the vapours
are almost entirely decomposed at the lowest possible temperature.
By these means the maximum quantity of rich gas possessing a maximum
illuminating capacity is obtained; that the nature of the materials employed will
admit the quantity of tar produced during the operation not exceeding about ten
per cent. of the weight of the heavy oil.
In order that the pipes for the passage of the gas may not become choked by
this small quantity of tar, a special apparatus is employed in connection with the
ascension pipe as next hereinafter described. The gas escape pipe opens into the
lower part of a chamber forming an enlargement of the said pipe and communicating
at its upper part with an ascension pipe in which the tar contained in the gas
proceeding from the improved apparatus hereinbefore described is condensed; after
flowing down along the sides of the said ascension pipe the tar is collected in the
chamber hereinbefore described, being prevented from re-entering the gas escape
pipe below the chamber by a lip or raised edge, and may then be drawn off when
required through a suitable pipe without interrupting the working of the
apparatus.
The apparatus is capable of working for about ten or eleven hours; the large
cylinder being opened, say, twice in a day, in order that the internal cylinder may
be taken out when foul and a clean cylinder lowered into its place, after which the
operation may again proceed as soon as the temperature is sufficiently elevated.
The inner cylinder when taken out of its place is incrusted with graphite or
carbon which has been deposited during the operation of decomposition, and which
may be detached with a suitable implement after the cylinder has been allowed
to cool.
In order to preserve the sides of the outer cylinder from being rapidly worn
out through being too much exposed to the action of the flame from the furnace,
walls or partitions are carried up for about one third of the height of the cylinder
between the sides of the cylinder or retort and the inlet for the flame, so that the
combustable gases from the furnace are caused to ascend a certain distance in the
chamber in which the retort is located before coming directly in contact with
the latter.
By the employment of the improved apparatus hereinbefore described it is
possible to decompose all the heavy oils of petroleum and schist or tallow, and even
tars obtained from coal and wood.