IMPROVEMENTS Invention of MANUFACTURE OF GAS FOR BURNING
Year: 1876

page_text: LETTERS PATENT to Thomas Boverton Redwood, of Fairlawn, North Finchley,
"IMPROVEMENTS IN THE
in the County of Middlesex, for the Invention of
MANUFACTURE OF GAS FOR BURNING."
PROVISIONAL SPECIFICATION left by the said Thomas Boverton Redwood at
the Office of the Commissioners of Patents on the 23rd June 1876.
THOMAS BOVERTON REDWOOD, of Fairlawn, North Finchley, in the County of
Middlesex. "IMPROVEMENTS IN THE MANUFACTURE OF GAS FOR BURNING."
This Invention relates to certain modifications in the method of applying a
process for the manufacture of gas from coal, for which a Patent was granted to me
last year, No. 2685. I have found these modifications to be advantageous in
working under some circumstances, and they are as follows:-
Instead of conveying the gas immediately as it issues from the retort through
the converting chamber or coverter, it is made to pass through the hydraulic main
before entering the converter, and in this way the gas produced in several retorts
may be conveyed through one and the same converter. I find the best mode of
bringing the gas into contact with the heated copper in the converter is to fill or
partly fill the converter with copper tubes, each of these tubes being about one inch
in diameter and from 12 to 18 inches in length. These are closely packed and
arranged in the converter in such a way that there shall be two or more groups or
bundles of them, each group filling the internal circumference of the converting
chamber or cylinder, while there shall be a vacant space or spaces left between the
separate groups, and the orifices of the separate tubes in the adjacent groups shall
not be exactly opposite each other; the current of gas is thus broken without its
being too much obstructed.
In cases where it may be desired to get a larger quantity of tar than would be
collected in operating as described in my Patent No. 2685, the gas may be carried
not only through the hydraulic main but also through the condensers before it
passes to the converter. In operating in either of these ways aqueous vapour as
well as tar will be separated from the gas before it reaches the converter, and as
one of the important improvements in quality which is effected in the gas by its
passing through the converter is due to the conversion there of bisulphide of carbon
into sulphuretted hydrogen, and as this conversion is promoted by the presence of
aqueous vapour, it is desirable to introduce water or its vapour into the converter
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page_text: with the gas, which may be done in any suitable way to the extent of about a pint
or more of water or an equivalent quantity of steam for every thousand cubic feet
of gas.
If the gas be passed through the converter after the condensation of much
of the tar and aqueous vapour, the object being principally that of converting bi-
sulphide of carbon into sulphuretted hydrogen, the converter may be used at a lower
temperature than is indicated in my Patent, No. 2685.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said Thomas Boverton Redwood in the Great Seal Patent Office on the 22nd
December 1876.
THOMAS BOVERTON REDWOOD, of Fairlawn, North Finchley, in the County of
Middlesex. "IMPROVEMENTS IN THE MANUFACTURE OF GAS FOR BURNING."
This Invention relates to certain modifications in the method of applying a
process for the manufacture of gas from coal for which a Patent was granted to me
last year, No. 2685. I have found these modifications to be advantageous in
working under some circumstances, and they are as follows:-
Instead of conveying the gas immediately as it issues from the retort through
the converting chamber or converter, it is made to pass through the hydraulic main
before entering the converter, and in this way the gas produced in several retorts
may be conveyed through one and the same converter. By this means also the gas
before entering the converter will be deprived of much of the solid and liquid
particles which it carries from the retort and which are deposited in the hydraulic
main in the form of tar. It is desirable to exclude as far as possible the less volatile
part of the tar and all solid particles of carbon and dust from the converter, as these
if deposited on the surface of the copper in the converter will prevent the copper
from exerting its peculiar and required action on the gas.
I have also found it advantageous, and in working with large volumes of gas
which pass quickly through the hydraulic main it is important to adopt some
method by which the solid and less volatile particles still retained in suspension
may be removed by a sort of process of filtration or separation after the gas leaves
the hydraulic main and before it enters the converter. This may be effected by the
use of Pelouze and Audouin's mechanical condenser, or by causing the gas to pass
through a cylinder with projecting longitudinal ribs on its inner surface, and a fan
rotating with great velocity in the axis of the cylinder, so as to cause suspended
liquid and solid particles to be aggregated by concussion.
This mechanical purification of the gas should be effected without cooling it and
while it is still at or near to the temperature at which it passes through the
hydraulic main. It may even be sometimes advantageous to increase the temperature
by means of a steam pipe or otherwise, because, with a view to the production of
some of the effects contemplated in the use of the converter, it is necessary to retain
as much as possible of the more volatile hydrocarbons which are present in crude
coal gas, and which, in contact with the red hot copper in the converter, are trans-
formed into permanent gases. I find the best mode of bringing the gas into contact
with the heated copper in the converter is to fill or partly fill the converter with
copper tubes, each of these tubes being about one inch or one inch and a half in
diameter and from 18 inches to 3 feet in length. These are closely packed and
arranged in the converter in such a way that there shall be two groups or bundles
of them, each group filling the internal circumference of the converting chamber or
cylinder while there shall be a vacant space left between the groups, and the orifices
of the separate tubes in the two groups shall not be exactly opposite each other.
The current of gas is thus broken without its being too much obstructed.
The two ends of each converting chamber or cylinder should be closed with
moveable lids or doors, which can be easily removed for the purpose of cleaning the
copper tubes by passing a wire brush through them, so as to remove any solid

page_text: particles that may accumulate there and which may be caused by the previous
imperfect cleansing of the gas in the manner already described.
It may sometimes be desired to produce and obtain the whole of the tar in the
state in which it has hitherto been usually obtained in gas making, while at the
same time the quality of the gas may be improved by depriving it of sulphur in
other form than that of sulphuretted hydrogen, and with this view the gas may be
carried not only through the hydraulic main but also through the condensers before
it enters the converter. In this case, as the contemplated improvement in the gas
will result from the decomposition of bisulphide of carbon together with water and
the production of sulphuretted hydrogen, and as most of the aqueous vapour which
the gas carries from the hydraulic main will have been separated by condensation
before it reaches the converter, it will be desirable to introduce water or its vapour
into the converter with the gas, which may be done in any suitable way to the
extent of a pint or more of water or an equivalent quantity of steam for every
thousand cubic feet of gas. In operating in this way for the purpose of trans-
forming bisulphide of carbon into sulphuretted hydrogen, the converter may be
used at a lower temperature than is indicated in my Patent, No. 2685.
I prefer to operate as follows:-I cause the gas as it comes from the hydraulic
main to pass through an apparatus, such as I have described for the removal of solid
and previously condensed liquid particles, and then in its still heated state it is
conveyed through a heated cylinder or retort lined with copper and packed with
copper tubes, as herein described, and called the converter. By this means the
volume of the gas is increased, and its quality, both as regards illuminating power
and freedom from sulphur in other form than that of sulphuretted hydrogen, is at
the same time improved.
In cases where it is desired to obtain the whole of the tar in the state in which
it has hitherto been usually obtained in gas making, the gas, after passing in the
usual way from the hydraulic main and through the condensers, may then be con-
veyed through the converter together with the vapour of water for the purpose of
reducing the quantity of sulphur in other form than that of sulphuretted hydrogen,
and in this case the converter may be kept at a temperature somewhat lower than
that of a cherry red heat. The converter should be heated externally by a fire, by
which it can be kept at the required temperature, and the gas after passing through
the converter is to be conveyed to the condensers and purifiers in the usual way.
What I claim is―
First. Causing gas obtained by distilling coal after it has passed through the
hydraulic main to come in contact with copper or an alloy of copper kept in a
highly heated state and arranged so as to expose a large extent of surface, sub-
stantially as described.
Second. The arrangement and use of the converter, substantially as described.
Third. The improvements in the manufacture of gas for burning, substantially as
described.
In witness whereof, I, the said Thomas Boverton Redwood, have hereunto set
my hand and seal, this Twenty-first day of December, in the year of our
Lord One thousand night hundred and gaventv.oiv