AN IMPROVED PROCESS FOR PREVENTING THE ACCUMULATION OF CARBON IN RETORTS USED FOR THE DISTILLATION OF CARBURETTED HYDROGEN
Year: 1877

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for the Invention of "AN IMPROVED
PROCESS FOR PREVENTING THE ACCUMULATION OF CARBON IN RETORTS USED
FOR THE DISTILLATION OF CARBURETTED HYDROGEN." A communication
from abroad by Watson Karr, of Frostburg, Alleghany County, State of Mary-
land. United States of America.
Sealed the 21st August 1877, and dated the 21st March 1877.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 21st March 1877.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middle-
sex, Patent Agent. "AN IMPROVED PROCESS FOR PREVENTING THE ACCUMULA-
TION OF CARBON IN RETORTS USED FOR THE DISTILLATION OF CARBURETTED
HYDROGEN." A communication from abroad by Watson Karr, of Frostburg, Alleghany
County, State of Maryland, United States of America.
In carrying out this Invention I take of semi-bituminous and bituminous coals in
the proportion by weight of about one of the former to twelve of the latter respec-
tively. (It has been found that that class of semi-bituminous coals known as
Cumberland or George's Creek is well suited for the purpose.) The retort being at
a working heat I deposit the semi-bituminous coal first in the back end of the same,
then complete the charge with the bituminous coal. It is to be understood as the
rule that the operation of thus combining the coals is to be continuous, that is to
say, both kinds of coal will ordinarily be used in each charge; but if the deposit of
carbon from a particular charge is very slight or scarcely appreciable the quantity
of semi-bituminous coal used in the succeeding charge may be diminished.
The appearance of the retort when the charge is withdrawn is a certain test,
indicating by the presence or absence of carbon formations a mean proportion of the
coals to be used by a slight increase or decrease of the semi-bituminous class.
The principle or rationale of this process is this:-The semi-bituminous coal
produces mainly hydrogen gas, which in passing from the rear to the front end of
the retort combines with the carbon which would otherwise be deposited on the

page_text: inner surface of the retort by the heavier gas distilled from the bituminous coal, thus
producing carburetted hydrogen.
The process economizes fuel, since the retort being always free from carbon, has
only its own thickness intervening between the fire of the furnace and the coal to
be carbonized.
It lessens the time required for eliminating the gas contained in a given amount
of coal (as compared with the time required when the surface of the retort is covered
with carbon formations), since the radiating surface of the retort is at its maximum
when free from carbon.
Further, the removal of carbon being destructive of the retort as well as expen-
sive, the present process by preventing its accumulation increases its durability.
Lastly, the process effects an economy in the consumption of coal, since it causes
the conversion into gas of carbon, which in the ordinary process is deposited on the
retort, and thereby wasted.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said Alexander Melville Clark in the Great Seal Patent Office on the 22nd
August 1877.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middle-
sex, Patent Agont. "AN IMPROVED PROCESS FOR PREVENTING THE ACCUMULA-
TION OF CARBON IN RETORTS USED FOR THE DISTILLATION OF CARBURETTED
HYDROGEN." A communication from abroad by Watson Karr, of Frostburg,
Alleghany County, State of Maryland, United States of America.
Mineral coal is commonly classed as anthracite, bituminous, and semi-bituminous,
according to the proportion of bituminous substances present. The bituminous
variety is used for the production of illuminating gas, but (for a reason herein-after
stated) in the process of distillation carbon is deposited on the roof and sides of the
retort. This deposit is increased as the gas making process continues, until the
cubical capacity and the inner radiating surface of the retort are diminished to such
an extent as to render its use no longer practicable. This deposit requires to be
removed by mechanical means, an operation which, aside from the matter of expense
for the labor involved, and also in consequence of the temporary disuse of the
retort, results in injury to the latter, and in time renders it unavailable for its
function. It is the chief object of the present Invention to avoid this and other
disadvantages attending or incident to the ordinary process of gas manufacture, and
this I effect by preventing the deposition or accumulation of carbon on the inner
surface of the retort by charging the latter with a combination of bituminous and
semi-bituminous coals in the manner I will now proceed to describe.
The practical operation is as follows:-The retort being at working heat I first
place a given quantity of semi-bituminous coal in the retort, and then complete the
charge with bituminous coals. In other words, the semi-bituminous coal is to be
placed in rear of the bituminous coal.
The principle of the Invention is explainable as follows:-In the distillation of
gas from the bituminous variety of coal the products evolved during the first part
of the process are the heavy hydrocarbon gases, together with a greater or less
quantity of free carbon, thus (C, H, +C), the free carbon of which (C) is deposited
by reason of the fact that an insufficient amount of hydrogen is at this time present
to combine with and utilize the same in the formation of gas. The last products
evolved in the process of distillation contain a sufficient proportion of light car-
buretted hydrogen gas (C, H), in which the hydrogen is in excess to prevent the
further deposition of carbou, but inasmuch as the excess of free carbon first given off
is deposited in crystalline form before the evolution of the excessive hydrogen of

page_text: the light carburetted hydrogen (C, H.) takes place, the excessive carbon of the first
part of the distillation and the excessive hydrogen of the last part of the distillation
are not associated simultaneously with their evolution, and the carbon not being in
a nascent state they do not therefore chemically unite to form a hydrocarbon, but
the gas produced is charged with an excessive quantity of hydrogen, which detracts
from its illuminating properties, while at the same time the retort is clogged with a
deposit of carbon, which prevents the best utilisation of the coal, and also to a large
extent obstructs the transmission of heat to the materials in the retort. To obviate
this difficulty I employ two kinds of coal, charged simultaneously. One of these
coals (the bituminous) evolves by reason of its richness the heavy carburetted
hydrogen (CH), and gives at the same time the deposit of carbon (C). The other
coal (the semi-bituminous) being less rich in carbon evolves from the outset only
light carburetted hydrogen (CH), in which hydrogen is in excess.
Now by
charging the retort with these two coals at once, it will be seen that we have two
coals evolving simultaneously and from the commencement, the one carbon in excess,
and the other hydrogen in excess, and inasmuch as the evolution of the free carbon
and the excessive hydrogen (i.e., the two extra equivalents of the light hydrocarbon)
takes place together and simultaneously, their nascent condition and intimate gaseous
association compels them to unite to form a hydrocarbon, thus.-

page_text: The appearance of the retort when the charge is withdrawn is a certain test,
indicating by the presence or absence of carbon formations a mean proportion of
the coals to be used by a slight increase or decrease of the semi-bituminous
variety.
Having described the nature of the said Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein-before in part recited Letters Patent is, in the manufacturo of illuminating
gas the process of preventing the accumulation of carbon in retorts by combining
bituminous and semi-bituminous coals, substantially in the manner described.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Twenty-second day of August, in the year of our
Lord One thousand eight hundred and seventy-seven.
A. M. CLARK. (L.S.)