IMPROVEMENTS IN THE MANUFACTURE OF GAS
Year: 1876

page_text: LETTERS PATENT to Louis Aimé Léo Elie Picot de la Peyrouse, M.D., of 4,
Finsbury Circus, in the City of London, for the Invention of "IMPROVEMENTS
IN THE MANUFACTURE OF GAS."
Sealed the 12th January 1877, and dated the 15th August 1876.
PROVISIONAL SPECIFICATION left by the said Louis Aimé Léo Elie Picot de
la Peyrouse at the Office of the Commissioners of Patents on the 15th August
1876.
LOUIS AIMÉ LÉO ELIE PICOT DE LA PEYROUSE, M.D., of 4, Finsbury Circus, in
the City of London. "IMPROVEMENTS IN THE MANUfacture of Gas."
This Invention relates to improvements in the production of ordinary illumi-
nating gas.
The improvements have for their object to obtain from a given quantity of coal
or other gas producing material a greater volume of gas both purer and of higher
lighting power than gas as now made.
By the process employed at the present day at gasworks the greater portion of
the volatile products obtained from coal by heat condense or split up to form a series
of bi-products which contain hydrogen necessary for the production of bi-carburetted
hydrogen or olefiant gas, which with acetylene, propylene, and butylene form the
greater part of illuminating gas. The reason why so small a proportion of illumi-
nating gas is obtained by the ordinary process is therefore the loss of hydrogen,
which instead of forming lighting gas is taken up by the formation of water, lightly
carburetted hydrogen, sulphuretted hydrogen, ammonia, tar, and empyreumatic oils.
Attempts have been made to remedy the evil by distilling coal at different tem-
peratures, but without much result. In fact, when coal is submitted to the lowest
temperatures at which the volatile products are generated, it produces a vast
quantity of bi-products, and but a small quantity of lighting gas. A high tem-
perature produces a greater volume of gas, but it is lighter, and its lighting power is
weaker, because the heavier and richer gases coming from the centre of the retorts
have to traverse the outer layers of coal, which are rapidly carbonized, and when in
the state of coke and no longer emitting gas decompose the olefiant gases as they
pass through them, and diminish their lighting power. A medium temperature gives
neither economy nor a sufficient quantity of gas.

page_text: According to my Invention I employ a method of producing gas which will
prevent to the fullest extent the condensation of watery and hydro-carburetted
vapours generated in the distillation of coal, and which will consequently prevent
the formation of bi-products by causing these vapours so soon as they are generated,
and by the immediate influence of a higher temperature, to pass into a gaseous state.
Such gases will be richer, purer than the ordinary lighting gases, and will not
require the ordinary washing process.
In carrying out my Invention either a single through retort may be used (that is,
a retort capable of being opened at either end), or two retorts placed side by sido,
and communicating with one another, so called twin retorts.
If a single through retort be used, a charge is at starting introduced into one half
only of the retort, the gas produced being led off from. the opposite end of the retort.
When the greater part of the volatile products contained in the coal have been
driven off, the passage of gas from this end of the retort is cut off, and a passage
opened for it from the opposite end. A charge of coal is then introduced into the
empty end of the retort. The vapours produced from this last charge have con-
sequently to pass through the incandescent and partially exhausted coal before
they leave the retort.
It is now that my improvements come into operation.
When the greater part of the volatile products have been driven off from the
second charge, the first charge is withdrawn and a new charge introduced in place
of it, and the vapours produced from it are caused to pass through the nearly
exhausted second charge, and thus the process is carried on continuously.
The two ends of the retort are heated by separate furnaces, so that either end of
the retort may be retained at the heat required independently of the other end.
When the operation is to be conducted in two retorts coupled together, or so
called twin retorts, one retort is first charged, and when the greater part of the
volatile products have been driven off from this charge, a charge is introduced into
the second retort, and the vapours produced from it are led off through the partially
exhausted charge in the first retort. When the second charge has had the greater
portion of the volatile products driven off from it the charge is withdrawn from the
first retort, and a fresh charge introduced in place of it, the vapours driven off from
this last charge being then conducted away through the second retort, and so on
continuously.
The two retorts are heated by separate furnaces, so that either of them can be
maintained at the desired heat independently of the other.
By the means above described the bi-products are reduced to a minimum, and the
hydrogen which would have gone to compose them is used in the production of
lighting gas. The gas produced will contain little or no ammonia, and the nitrogen
contained in the coal will enter into combination with carbon in lieu of forming
ammonia.
The gas produced may be purified by being passed through the ordinary dry
purifiers, first through a purifier charged with lime sprinkled with oxygenated
water, or with a solution of some salt containing a large quantity of oxygen, which
it can give up without difficulty. The other trays may as usual be charged with
oxide of iron.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Louis Aimé Léo Elie Picot de la Peyrouse in the Great Seal Patent
Office on the 14th February 1877.
LOUIS AIMÉ LEO ELIE PICOT DE LA PEYROUSE, M.D., of 4, Finsbury Circus, in 5(
the City of London. "IMPROVEMENTS IN THE MANUFACTURE OF Gas."
This Invention relates to improvements in the production of ordinary illumi-
nating gas.

page_text: The improvements have for their object to obtain from a given quantity of coal
a greater volume of gas both purer and of higher lighting power than gas as now
made, consequently ensuring a great economy in the production of ordinary lighting
gas, whether it be manufactured from coal or from oil, wood, resin, bitumens, petro-
leum oils, tars, either alone or together with coal or coke.
By the process employed at the present time at gasworks the greater portion of
the volatile products obtained from coal by heat condense or split up to form a series
of bi-products which contain hydrogen necessary for the production of bi-carburetted
hydrogen or olefiant gas, which with acitylene, propylene, and butylene, form the
greater part of illuminating gas. The cause of the small quantity of lighting gas
obtained by the ordinary process is therefore the loss of hydrogen, which instead of
forming lighting gas is taken up in the formation of water, lightly carburetted
hydrogen, sulphuretted hydrogen, ammonia, tar, empyreumatic or essential oils, all
of them formed to the detriment of the lighting gas, of which hydrogen is the
principal constituent. Such a gas necessarily requires purification.
It is well known that the tar and empyreumatic or essential oils separate and
condense on cooling.
By means of lime the carbonic acid is fixed.
The ammoniacal salts and sulphuretted hydrogen being soluble in water, the gas
is washed to free it from these hurtful products, but acetylene and olefiant gas
being also partly soluble in water, a new source of impoverishment of the lighting
gas arises.
To remedy this state of things gas coal has been distilled in single retorts at
different temperatures, but without much result. In fact, when coal is submitted to
the lowest temperatures at which the volatile products are generated, it produces a
vast quantity of bi-products, and but a small quantity of better lighting gas. A
high temperature produces a greater volume of gas, but it is lighter, and its lighting
power is weaker; the high temperature has also the disadvantage of choking up
with a sooty deposit the pipes by which the gas is led off. A medium temperature
gives neither economy nor a sufficient quantity of gas.
It will be readily understood then that many efforts have been made to furnish to
the coal during its volatilization a quantity of hydrogen from extraneous sources, as,
for example, hydrogen arising from the decomposition of superheated steam, or of
oil thrown on to incandescent coal or naphtha, or solid or liquid bitumens together
with resin, &c. I am not aware that any of these processes are adopted in
practice.
The true method of producing gas will be that which will prevent to the fullest
extent the condensation of the watery and hydrocarburetted vapors generated in
the distillation of coal, and which consequently will prevent the formation of bi-
products by causing these vapors so soon as they are generated, and by the imme-
diate influence of a higher temperature, to pass into a gaseous state. Such gases
will be rich, pure lighting gases, and will not require the washing process.
The kinds of apparatus which in continuous working are for the shortest time
exposed to cooling, and the different parts of which can at pleasure be continuously
heated to different temperatures, will be the most suitable for attaining the desired
end.
According to my Invention I effect the above operation either in a single "through"
retort (that is, a retort closed at each end with a mouth-piece), having at each end
an ascension pipe, and heated by preference.by a separate furnace at each end, but
it might be by a single furnace; or I effect the operation in two or more retorts
pinced side by side (called twin retorts) communicating with one another. The
retorts I work in the manner herein-after described.
Mode of Working in Single Retorts and in Twin Retorts.-If single retorts are
used, such as shown at Figures 1, 2, 3, 4, 5, and 6, a charge is at starting introduced
into one half only of the retort A, B, Figure 3, from the side A, for example.
The opposite extremity will be closed, and the valve S on the ascending pipe B will
be opened to allow the products of distillation of the coal to pass off.

page_text: When the greater part of the volatile products contained in the coal have been
driven off the valve on the ascending pipe B will be closed, and that on the
ascending pipe A opened. A charge of coal will be introduced at the extremity B
into the empty half of the retort, and the retort then closed at that end. The vapors
. produced from the last charge of coal introduced at the end B will consequently
have to pass away through incandescent coal coke in the first half (A,) and the
resulting gaseous products leave the retort by the pipe A. The results sought for
now commence to be obtained. By this means the products of the distillation of
coal are converted into lighting gas with the least possible loss of hydrogen, and
with the least possible production of bi-products, so abundant in the ordinary
process of working.
A small test gas burner attached to each of the ascending pipes at the two ends
of the retort will show the quality of gas produced.
When the quality of the gas shows that its illuminating power is diminishing,
the operation is stopped to empty the half of the retort containing the coke, as care
must be taken not to completely exhaust the partially formed coke of gaseous pro-
ducts, as then absorption and decomposition of the illuminating gases passing
through it would take place. The valve S on the ascending pipe A is then closed,
and that on the ascending pipe B opened. The end A of the retort is emptied, and
the coke withdrawn, and is at once replaced by a new charge of coal, the vapours
from which will in their turn pass through the partly carbonized coal in the end B,
and in this way the operation is carried on continuously. Decrease of temperature,
always prejudicial to the end to be obtained, is thus avoided.
It will be seen that the retort rests over two distinct furnaces formed in such a
way as to give at pleasure different temperatures to the two halves of the retort.
The highest temperature is applied to that half of the retort which contains the
partially carbonized coal through which the vapours from the new charge of coal
have to pass; this half ought to be maintained at a high temperature, but as uniformn
as possible.
To facilitate the passage of the gaseous products the coke may be broken from :
time to time.
Twin Retorts. When multiple retorts are used, Figures 8, 9, 10, 11, 12, and 13, the
operation is conducted in the following manner:-The first charge of coal is introduced
into one only of the two retorts, say, for example, the retort A. When this retort has
been filled, the opening into such retort is closed, taking care also to close the valve on
its ascending pipe, whilst the valve on the ascending pipe of the retort B is opened.
Under the influence of the heat the products vaporized from the coal in the rotort A
pass off through the empty retort B and its ascending pipe; so soon as the greater
part of the volatile products of the coal in the retort A have been driven off, the
valve on the ascending pipe A. is opened and that of B closed, and a charge of coal
is introducud into the said retort B. The volatile products coming from the
retort B pass from back to front through the retort A, and aro converted into
lighting gas, which is conveyed away by the pipe A.
When the coal contained in the retort A is nearly exhausted, which will be
known by the light given by the test burner, the valve of the retort A is closed and 4
that of B opened, and a new charge of coal is introduced into A. The volatile pro-
ducts of the retort A have then to pass through the partially carbonized coal in the
retort B, and are led away by its ascending pipe. The alternative charging of the
retorts A and B is carried on continuously, as above described, whereby the opera-
tion is rendered continuous, and the coolings which take place will not be of 5
importance.
It will be seen that there are two separate furnaces, the one for the retort A, the
other for the retort B; a high uniform temperature can thus be maintained in the
retort containing the partially carbonized products, through which the vaporized
products from the other retort have to pass. In a similar manner the process above 5
described may be carried out with these retorts, one containing the fresh charge of
coal, the other the partially formed coke.

page_text: By the means above described the bi-products are reduced to a minimum, and the
hydrogen which would have gone to compose them is used in the production of
lighting gas. The gas produced will contain little or no ammonia, and the nitrogen
contained in the coal will enter into combination with carbon in lieu of forming
ammonia.
The gas produced may be purified by being passed through the ordinary dry
purifiers, first through a lime purifier charged with lime well sprinkled with oxy-
genated water, or with a solution of some salt containing a large quantity of oxygen,
which it can give up without difficulty. The other trays are as usual charged with
oxide of iron, but the last tray will be charged with a sufficient quantity of slack
lime to retain the carbonic acid and the sulphurous products remaining in the gas.
The letters of reference used apply to the same parts in the two systems of
apparatus.
Figures 1, 2, 3, 4, 5, 6, 7, shew a set of single retorts similar to ordinary retorts,
except that they can be opened at both ends, and can be charged alternately at
either end, whilst the gaseous products are led off in the same manner.
Figures 8, 9, 10, 11, 12, 13, 16 show details of the system of multiple or twin
retorts.
A, A, A, B, B, B, mouth-pieces of retorts (one opened the other closed) by which
the contents of the retort is alternately charged and discharged, also ascension and
dip pipes; C, union of the twin retorts; D, separating partition and flue walls;
E, horizontal and vertical fluos; F, A, furnace below the retort A; F, B, furnace
below the retort B; H, hydraulic mains; L, cup levers; O, O, retorts; S, sliding
valve placed on the ascending pipes; C, A, C, B, and C, A, C, B, cups in hydraulic
mains (see Figure 16).
23
Figures 1 and 2, side view, front view, and elevation of a single "through"
retort, with two furnaces F, A, F, B; two mouth-pieces A, B; two ascending pipes
A, B; two descending dip pipes and two valves on the rising pipes S, A, S, B;
and hydraulic main H.
Figures 3 and 4, longitudinal and transverse sections of Figures 1 and 2, with
the horizontal and vertical flues E, E; retort O; and division walls D.
The furnaces F, F, and sections of hydraulic main, with the position of the cups
and manner of working them by levers L, L, is shewn at Figure 16; or if preferred,
and as is recommended, slide valves S, S, may be placed on the ascending pipes.
Figure 5, horizontal section of Figure 3 taken at the line A, B, shewing the
spring of the arches as well as the retort O on its bed; the division walls D, D; the
flues E; and mouth-pieces A and B.
Figure 6 is a ground plan of Figure 3, showing the bottom and sides of the
flues E below the retort O, the two furnaces A, F, and B, F, one furnace at each
end, in such manner that they can be worked separately or together, and raised
to different heats.
Figure 7, plan view of Figures 1 and 2, showing the position of the hydraulic
mains and of the ascending and horizontal pipes leading from the mouth-pieces of
the retort A and B.
Twin Retorts.-Figures 8 and 9, side and front view of a set of 4 twin retorts A, B,
and A, B, with their four mouth-pieces, 4 ascending pipes and descending dip pipes
A, A, and B, B, with four cut-off cups C, A, C, B, C, A, C, B, in the hydraulic main H,
and the means of operating them by the levers L (Figure 10). A, A, retorts first
charged; the dip pipes are closed by the valves A, S, and A, S; the retorts B will
then be free to allow gas to pass by the ascending pipes, whose valves B, S, and
B, S, are open. The same result can be attained by the movement of the cups.
The cups C, A, and C, A, being closed, the cups C, B, and C, B, will be open
(Figure 16), and vice versa whenever it is necessary.
Figures 10 and 11, longitudinal and transverse sections of Figures 8 and 9,
showing the twin retorts O, O, with their connections C, C; division walls D, D ;
Blues E, E; two furnaces A, F, and B, F, with their ash-pit; these furnaces can be
worked simultaneously or separately.

page_text: Figures 12 and 13, horizontal section of Figures 8 and 9 on the line A, B, and of
Figures 10 and 11 on the line A, B, shewing the twin retorts on their beds, the
division walls D, D, and the flues E, E.
Figures 14 and 15, longitudinal and transverse clevation of a set of retorts the
same as Figures 1 and 2, with the exception that they are furnished with two
hydraulic mains in place of with one only. The admission of gas to the bydraulic
mains can be controlled either by the two cups C, A, C, B, suspended from a
lever L, Figure 16, or better by means of valves A, S, and B, S, on the ascending
pipes.
Figures 11, 12, and 13 show in dotted lines that the twin retorts may be con-
tinued through, so that each retort has two mouth-pieces to allow the discharging of
coke to be effected instantaneously from both sides.
Having thus described the nature of my Invention, and the manner of performing
the same, I would have it understood that I claim, the manufacture of gas by the
means substantially as herein-before described.
In witness whereof, I, the said Louis Aimé Leo Elie Picot de la Peyrouse,
have hereunto set my hand and seal, this Twenty-ninth day of January,
in the year of our Lord One thousand eight hundred and seventy-seven.
L. A L. E. P. DE LA PEYROUSE