IMPROVEMENTS IN THE MANUFAC TURE OF GAS FOR BURNING
Year: 1877

page_text: LETTERS PATENT to Theophilus Redwood, of Earlscroft, Lower Clapton, Professor
of Chymistry, and Thomas Boverton Redwood, of Fairlawn, North Finchley,
Consulting Chemist, for the Invention of "IMPROVEMENTS IN THE MANUFAC
TURE OF GAS FOR BURNING."
f
Sealed the 7th August 1877, and dated the 30th May 1877.
•
PROVISIONAL SPECIFICATION left by the said Theophilus Redwood and
Thomas Boverton Redwood at the Office of the Commissioners of Patents on
the 30th May 1877.
THEOPHILUS REDWOOD, of Earlscroft, Lower Clapton, Professor of Chyinistry,
and THOMAS BOVERTON REDWOOD, of Fairlawn, North Finchley, Consulting Chemist.
*IMPROVEMENTS IN THE MANUFACTURE OF GAS FOR BURNING."
"
For this purpose I submit the gas as it issues from the retort or hydraulic main
to a process by which it is deprived of the denser and more easily condensible parts
of what is usually deposited as tar, while the more volatile of the condensible
hydrocarbons are retained in it, and the gas, after being so treated, is mixed with
steam, which may be superheated, and the mixed gas and steam are then drawn by
an exhauster through a red-hot cylinder or retort, in which they are brought into
contact with sulphate of lime, or a sulphate or oxide of any of the alkaline earths,
or with products resulting from the chemical changes which may take place in either
or any of these, by which means sulphur contained in the gas in other form than
that of sulphuretted hydrogen is removed from the gas; and the gas and steam aro
then brought into contact with red-hot iron or other metal so arranged as to present
a large surface to the gas without obstructing its passage, by which means the
vapours of condensible hydrocarbons are converted into permanent gas, and the
quantity and quality of the gas produced is thus increased.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Theophilus Redwood and Thomas Boverton Redwood in the Great
Seal Patent Office on the 29th November 1877.
THEOPHILUS REDWOOD, of Earlscroft, Lower Clapton, Professor of Chymistry,
and THOMAS BOVERTON REDWOOD, of Fairlawn, North Finchley, Consulting Chemist.
"IMPROVEMENTS IN THE MANUFACTURE OF GAS FOR BURNING."
The objects of this Invention are to increase the volume of the gas produced
from coals without diminishing its illuminating power, and to reduce the quantity
of sulphur retained in the gas in other form than that of sulphuretted hydrogen.
We effect the first of these objects by heating the gas in contact with solid surfaces
after the removal of the tar but-while-it-retains-the-vapours-of-liquid-hydrocarbons
diffused through it, and we effect the second object by heating the gas mixed with
steam in contact with masses of plaster of Paris.
In carrying out the proposed objects, coal gas, which has been produced in the
usual way, is subjected, as it issues from the hydraulic main, to a process by which
it is deprived of heavy, tarry, and other particles which were held in suspension,
while the more volatile of the condeusible bydrocarbons are retained in it. This may
be effected by using the condensing or separating apparatus of " Pelouze and Audouin,"
of Paris; or the same object may be accomplished by conveying the gas through
a cylinder in which there are fans, which are made to revolve on an axis coinciding
with that of the cylinder with great velocity, say, at the rate of a thousand revolu-
tions or more in a minute, by which means the suspended particles of tar, with any
particles of dust, may by concussion be made to coalesce and separate from the gas
and uncondensed vapours. This fanning apparatus may be rendered more effective
by having longitudinal projections or ribs on the inner surface of the cylinders, and
transverse diaphragms or stops between the fans extending from the axis about
half-way to the outer edge of the fans, by which means the gas is more thoroughly
broken up and subjected to concussion. The apparatus used for this purpose should
be fixed near to the hydraulic main, and means should be adopted for keeping the
gas as it passes to and through the separating apparatus at or near to a temperature
of 200° Fahrenheit, so that while the tar and dust are removed the hydrocarbon
oils may be retained in the gas.
The gas is then conveyed through an apparatus called a converter, which may
consist of an iron cylinder or retort fixed and heated like an ordinary gas retort,
and filled or packed with masses of plaster of Paris. We prefer to have the
converter so arranged that it shall consist either of two vertical tubes connected so
that the gas shall pass up one and down the other, or of two horizontal tubes placed
side by side, and one vertical tube, these being connected together so that the gus
entering at the end of one of the horizontal tubes shall pass at its further end into
the second horizontal tube, through which it will pass to the vertical tube. These
tubes may be heated by one fire, the vertical tube of the last-named arrangement
receiving the residue of heat from the flues by which the horizontal tubes have-been
-heated and being therefore less heated than the horizontal tubes. These tubes
-should-be-made-of cast iron, and they inay with advantage be lined inside with fire-
clay. The horizontal-tubes-may be ten or twelve feet long, and the vertical tubes
about six or eight feet long. They may be ten or twelve inches-in-diameter inside.
In filling or packing_the-tubes-with-plaster of Paris we prefer to use perforated
blocks-of-the-plaster for the horizontal tubes, and globular pieces, each about the
size of an egg, for the vertical-tubes.---
The perforations in the blocks may be from an inch to an inch and a half in
diameter, and the blocks may be twelve or eighteen inches long, and of a diameter
suited to the cylinders into which they are intended to fit.
In putting the blocks into the cylinders there may be vacant spaces of six or
eight inches between the blocks.

page_text: The vertical tube is to be filled with the globular masses which are intended to
break up the current of gas and present a large surface in contact with it.
In making the perforated blocks and globular or other masses we sometimes mix
clay or cement with the plaster of Paris for the purpose of increasing their firmness
and strength.
Perforated discs or blocks of fire-clay or bundles of iron tubes, one or two inches
in diameter, may be used in addition to the plaster of Paris for the purpose of
communicating the required heat to the gas.
The cylinders being thus filled or packed, are to be heated until they and their
contents have acquired a cherry-red heat, and this temperature, or one nearly
approaching to but not exceeding it, is to be maintained throughout the process,
while the gas, as it issues from the Pelouze or other separating apparatus, is to be
drawn through them by means of an exhauster, together with a small quantity of
steam, either superheated or otherwise, which should enter the converter with the
gas for the purpose of diluting and expanding it. We find it desirable to keep up
an exhaustion in the converter corresponding to a depression of three or four inches
of water in the pressure gauge, and to keep such a quantity of steam diffused
through the gas as shall increase its expansion to a slight extent without reducing
the temperature below a dull cherry-red heat, or the point at which the vapours of
liquid or solid hydrocarbons are broken up into permanent gases.
By these means the volume of the gas may be increased to the extent of 20 per
cent. or more without any diminution but rather with an increase of its illuminating
power, and the quantity of sulphur in other form than that of sulphuretted hydrogen
may at the same time be greatly reduced.
After treatment as herein described the gas is to be purified from ammonia,
sulphuretted hydrogen, and carbonic acid in the usual or any suitable way.
In the place of lime other sulphates of oxides of alkaline earths may be made
use of, but lime is to be preferred.
We would remark that the use of an exhauster to draw the gas through the
converter is an important feature of the Invention, as the gas will endure a higher
temperature without injury to its illuminating quality when at a pressure less than
atmospheric than when it is condensed by the application of pressure to drive it
through the apparatus.
This part of our Invention is also applicable when producing gas from petroleum
or hydrocarbon vapour by passing it, together with steam, through a converter, such
as that described.
When the hydrocarbon contains sulphur the converter may with special advantage
be charged with sulphate of lime.
Having thus described the nature of our said Invention and the manner of
performing the same, we would have it understood that we do not confine ourselves
to the details of our process as herein set forth, but we claim,-
The treatment of illuminating gas to increase its volume and to reduce the
quantity of sulphur in other form than sulphuretted hydrogen, by causing it, in the
presence of aqueous vapour, to pass amongst heated plaster of Paris or sulphate of
lime or other sulphate of the oxide of an alkaline earth.
We also claim in the manufacture of illuminating gas, the use of an exhauster
drawing gas, or it may be hydrocarbon vapour and steam, through a converter as
above described.
In witness whereof, I, the said Theophilus Redwood, have hereunto set my
hand and seal, this Twenty-sixth day of November, in the year of our