Improvements in and relating to Retorts for the Destructive Distillation of Shale.
Year: 1899

page_text: Date of Application, 25th July, 1899-Accepted, 26th Aug., 1899
COMPLETE SPECIFICATION.
Improvements in and relating to Retorts for the Destructive
Distillation of Shale.
We, WILLIAM YOUNG, of Priorsford, Peebles, Chemical Engineer, and JOHN
FYFE, of 1, Montgomerie Drive, in the City of Glasgow, Shale Oil Manufacturer,
do hereby declare the nature of this invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:-
This invention has for its object to improve the construction and method of
operating retorts used in the destructive distillation of shale in order to overcome
difficulties which have been experienced in operating them.
In the ordinary arrangement known as the Young & Beilby system in which
the retorts are composed each of an upper metallic section and a lower firebrick
section and are provided with chambers or hoppers at their upper ends, these
upper ends become gradually filled up with hard carbonaceous matter and this
necessitates the periodical stopping of the retorts to have such matter removed.
The shale residues get fluxed and fixed to the side walls of the lower of higher
temperature section of the retorts, where they can as a rule be removed only by
stopping and cooling down the retorts. The residues are further liable to pass
through the retort in an imperfectly exhausted condition whereby loss is entailed,
and in so doing they pass more quickly down the front or side of the retort next
the discharging door thus interfering with the regular distillation and treatment
of the shale. It is also found that when air and steam are used difficulty arises in
regulating the quantities and proportions of steam and air used to burn the carbon
out of the shale residues in order to obtain the desired result whilst preventing
obstructions due to fluxing of the residues.
Our improved construction of retort which is designed to obviate these and like
objections to the existing retorts is represented in the accompanying drawings
in vertical section at Figure 1 and in sectional side elevation at Figure 2 which
shows a bench of retorts divided into ovens of eight retorts. Each of the retorts is
composed of four sections, vizt., a hopper redistillation chamber A at the top, a
metallic section B, a firebrick chamber C, and a combustion chamber D at the
bottom. The fire brick section C and the metallic section B are heated externally
by combustible gas admitted to the usual arrangement of flues S and in starting
or when the temperature is below the normal, by means of hot gases from small
producers E which are formed at intervals in the division wall of the brickwork
base F of the bench of retorts. These fire gases after being applied to the retorts
pass up by suitable flues to flue spaces A¹, around the hoppers A and serve also to
supply external heat to said hopper walls. The shale is fed into the hoppers A
at the top in the usual way, passes thence in succession down the metallic and
brickwork sections B and C, and after being subjected to the usual distillation,
as in the Young & Beilby system, reaches the combustion chambers D, wherein
the carbon remaining in the residue is consumed, the ash and spent shale being
drawn off through doorways G at the lower ends of said chambers.
Each combustion chamber D is made of large capacity and in it the carbon that

page_text: may be left in the shale residue as it leaves the retort is burned by means of a
carefully adjusted mixture of steam and air introduced into the bottom of the
chamber through the pipe d. This chamber is not externally heated by fire but
receives the spent shale from the retort in a red hot condition. The further supply
of heat in the combustion chamber is therefore wholly due to the burning of the
carbon by the introduced air and steam, and all danger of the fluxing and fixing of
the shale residue to the walls of the combustion chamber is avoided. To enable the
shale residue to be discharged with the minimum of labour, the bottoms of these
combustion chambers, instead of being of a curved form, are each constructed with
an inclined bottom D¹, at such an angle that, whilst not sufficiently steep as to
cause the shale residue to slip or fall out by gravitation alone, will yet require
very little manual labour to cause it to do so. To prevent the shale coming down
the front more rapidly than down the back, there is fixed in the front of the com-
bustion chamber a shelf or perforated grating 12 inclining backwards at an
angle corresponding to that of the opposite side or back, so as to throw the shale
residue well back upon the inclined bottom D' of the combustion chamber, so that
when shale is withdrawn it comes down equally all over the retort.
The combustion of the last portion of the carbon left in the shale residue in
the large combustion chamber or at the bottom of the retorts, by means of the
mixture of steam and air, enables the full yield of ammonia to be obtained without
employing such a high temperature to the walls of the retort, and thereby fluxing
is prevented; and as the quantities of steam and air admitted to the bottom of the
combustion chamber are necessarily limited, any further quantity of steam need-
ful for the proper treatment of the shale is admitted into the bottom of the retort
proper by pipes & immediately over the combustion chamber D, and this steam still
further reduces the danger of fluxing. But in case that from any cause, fluxing
should take place, the retorts are provided with sloping tubes or poker holes I, I',
extending through the walls by which ready access to the inside of all parts of
the retort, where the residue is likely to flux, can be got by means of iron rods
to clear away obstructions.
To successfully burn the carbon remaining in the shale residue when it reaches
the combustion chamber, so as to obtain the maximum yield of ammonia, it
is necessary that the air admitted should have an approximate relation to the
quantity of carbon to be burned, and that it should be accompanied or mixed with
a proportionate quantity of steam. Should the air be much greater than that
necessary, the excess will find its way into the externally heated retort, and there,
by the increased temperature produced by the internal combustion, and the
heat supplied from the outside, lead to the fluxing of the shale residue. Even
when the air is of the right quantity, if the quantity of steam mixed with it is
excessive, the excess of steam would so reduce the temperature of the shale
residues in the combustion chamber D) as to prevent the air burning the carbon,
and the carbon left in the shale residues would not only be lost, but the air in
passing up into the retort and coming into contact with the shale residues receiving
heat through the walls of the brickwork of the retort would enter into combustion
with the heated carbon, leading to an excessive local temperature which would be
liable to cause fluxing of the shale. On the other hand should the proportion of
steam to air be too small, the combustion in the combustion chamber might be so
active as to produce a temperature destructive of the ammonia, and which might
even flux the shale residues in that chamber, and should the air not be in sufficient
quantity the residues will reach the discharge opening still containing carbon.
Whichever of these conditions exists is shown by the state of the shale residues
reaching the discharge opening G. and in order to readily bring about the
necessary adjustment of the quantities and proportions of steam and air, the
improved retorts are provided with a special device for the regulated admission
of the necessary quantity of air, one form of which is shown at Fig. 3 of the 5
drawings.
This arrangement consists of a casing or vessel L through the centre of whose

page_text: cover is an opening or orifice L¹, provided with a valve or cover M for the
regulation of the size of the opening through which the air has to pass. The air
is drawn in through this regulating opening by any suitable exhausting arrange-
ment, (preference being given to a steam jet exhauster) through the pipe N
standing up, and passing away through the bottom of the containing vessel. To
maintain an uniform exhaust at the orifice or opening L' the arrangement is
provided with the annular gasholder or bell through the crown of which
is an air opening 01 directly over which is fixed the valve or cover P. The
gasholder or bell is sealed in the water contained in the casing, and to allow the
sealed bell to rise and fall, air is admitted by the pipe Q. The exhaust in the
pipe N may vary very considerably but must be so maintained as to lift the
gasholder, but whatever may be the exhaust on the pipe N, the exhaust in the
space over the gasholder, into which the air is admitted through the regulating
orifice L¹ will be maintained uniform and equal to that which will lift the gas-
holder or bell, for, as the exhaust upon the pipe N is increased, or the size of
the orifice L¹ is diminished, the gasholder will rise, bringing the central open-
ing nearer to the valve P, and thus lessen the passage of the air from the
chamber over the valve into the pipe N till a balance is attained, and vice versa,
on the vacuum on the pipe N falling, or the orifice L' being enlarged, the gas-
holder will fall till a balance is again effected. The current of the air can thus
be maintained perfectly uniform. The amount of the exhaust necessary to lift
the holder is shown by the water gauge R on the side of the casing. By loading
the holder the exhaust can be increased if so desired.
The regulated or measured volume of air on its way to the combustion chamber
is made to pass through a vessel and come into intimate contact with the hot
exhausted ammoniacal water as it flows from the ammonia still, the air is thus
loaded with such a quantity of steam, that the quantity added at the steam jet or
other exhauster is made sufficient for the proper combustion of the residual carbon
left in the spent shale in the combustion chambers. Besides, should the hot
ammoniacal water leaving the ammonia stills be at any time not perfectly denuded
of the ammonia, such ammonia is taken up by the air and recovered.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is:
-
1. Retorts for the destructive distillation of shale and the recovery of the
nitrogen left in the residues as ammonia, said retorts being so constructed that the
ordinary Young & Beilby process is supplemented by the application of fire gases
to the external surface of deep hoppers to ensure the redistillation of the condensed
oils and prevention of the choking of the retort necks, and by the provision of
large combustion chambers below the externally heated fire brick sections of the
retorts for effecting the combustion of the residual carbon by means of steam and
air supplied in suitably adjusted proportions substantially in the manner set
forth.
2. In combination with retorts for the destructive distillation of shale, and
the recovery of nitrogen from the residues as ammonia, a combustion chamber
having an inclined bottom set so near the angle of rest and movement, that the
residues whilst not self discharging, will yet be discharged with the minimum of
abour, such combustion chambers being provided with a grating or inclined plate
set at an opposite but similar angle to the bottom to regulate and direct the
lownward course of the shale, substantially as described.
3. Providing retorts (in which the shale residues are treated with steam, or
team and air, for the recovery of the nitrogen as ammonia) with poker holes
assing through the side walls for the detaching of the shale residue when it
luxes, substantially as described.
4. Retorts (for the destructive distillation of shale, and the treatment of the

page_text: residues) constructed so as to be heated and operated substantially as hereinbefore
set forth with reference to the accompanying drawings.
Dated this 24th day of July 1899.
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents, 62, Saint Vincent Street, Glasgow,
Agent for the Applicants.