Improvements relating to the Dry Distillation of Wood and Kindred Materials.
Year: 1899

page_text: Date of Application, 2nd Oct., 1899-Accepted, 25th Nov., 1899
COMPLETE SPECIFICATION.
Improvements relating to the Dry Distillation of Wood and Kindred
Materials.
I, FRANZ SCHMIDT, Ph.D., of 107, Kölnische Strasse, Cassel, in the German
Empire, Chemist, 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, reference being had to the accompanying
drawings and to the letters and figures marked thereon, that is to say:-
This invention relates to the dry distillation of wood, saw dust, and other wood
waste, wood briquettes, and kindred materials, and it has for its object to
render overheating in the retort impossible, and thus to improve the yield of
the material under treatment.
Retorts usually employed for effecting the dry distillation of wood prove
exceedingly defective as, in the course of distillation a portion of the product
of distillation comes into contact with the red hot walls of the retort, the conse-
quence being that part of the methyl alcohol, acetic acid, etc., are destroyed,
and the output is thus considerably reduced.
As is well known, the heating of the retorts (which are usually arranged
vertically) is effected in an upward direction by means of the waste gases.
Further, as the charge in the retorts shrinks in proportion as the distillation
proceeds, the walls of the retort gradually become naked in a downward direction,
and over-heat rapidly, whereby a decomposing action takes place upon the pro-
ducts of distillation as they pass along the said over-heated parts in leaving the
retorts. It is only practicable, to a limited extent, to counteract the heating
effect by regulating the heating gases.
Now, the object of the present invention is to obviate this defect and to utilize
the shrinkage of the charge to cause fresh material to enter the retort from a
hopper or magazine.arranged on the top thereof. In this manner the uncovering
of the retort walls and the injurious over heating resulting therefrom are entirely
prevented.
The size of the hopper is dependent upon the nature of the material to be
distilled, and is so adjusted that the resulting carbonised material occupies a
slightly smaller space than the working capacity of the retort. Thus the same
amount of labour previously required for the treatment of one charge is now
sufficient for distilling a double amount of material, or, in other words, for
distilling one and the same quantity of material, only one half the number of
retorts previously employed is required. Another consideration is, that owing
to the more efficient utilization of the heat, the carbonisation takes place in a
considerably shorter time than heretofore.
The hopper is preferably cylindrical, or conical, and is placed upright on the
top of the retort. The lower end is open, whilst its upper end has an opening
capable of being closed gas-tight and serving as the feed opening for the. charge.
The discharge pipe for the products of distillation is arranged laterally, at the
lower part of the hopper, and is suitably controlled. This hopper is placed

page_text: either directly over the mouth of the retort, or upon an intermediate annular
piece to which the discharge pipe is connected. The latter arrangement is
preferable, as it is easier of construction, and as it admits of more ready cleaning.
The most suitable arrangement is, however, to so construct the apparatus that
the discharge is effected from the bottom, this latter being then fitted with a
door, otherwise it would be necessary, when effecting the discharge through the
mouth of the retort, to first lift off the hopper.
Although sometimes more suitable, yet it is not necessary to construct the
retort and hopper separately, as the invention may also be carried out by
doubling the length of the retort, and providing the top and bottom with a
closable opening, the discharge pipe then starting from the middle of the retort.
The invention is likewise applicable to inclined and horizontal retorts, but
in the latter case some mechanical arrangement is required to evenly distribute
the material, as it is gradually charged.
The accompanying drawings shew diagrammatically convenient forms of
apparatus for carrying out the improved method, similar letters of reference
indicating like parts.
Fig. 1 illustrates partly in horizontal section an upright retort with a cylin
drical hopper arranged directly upon its mouth, the discharge being effected
from the bottom.
Fig. 2 represents an upright retort with a cylindrical hopper, the latter being
supported by an annular piece placed over the mouth of such retort, and carrying
the discharge pipe.
Fig. 3 also represents an upright retort with supporting piece and a conical
hopper, but the discharge is effected through the mouth of the retort.
Fig. 4 shews a horizontal retort with a cylindrical hopper arranged above
its mouth.
Figs. 1 and 3 shew the masonry in which the retort is set.
As will be seen from Fig. 1, the bottom of the retort a inside the masonry g
is provided with a tapering bottom piece a¹ having a discharge door c. The mouth
of the retort is surrounded by a flanged rim a serving as a support for the
cylindrical hopper . The top of the said hopper is provided with a feed door d
and the discharge pipe e is arranged laterally at the bottom, the latter being
fitted internally with a perforated pipe or strainer e. At the top of the hopper
there is a second discharge pipe f, (indicated in dotted lines) which is utilized
in case the distillation is to take place under a reduced pressure. is the flue.
During working, the doors c and d are kept closed. Owing to the progressive
distillation and carbonisation, the wood shrinks, and in proportion as it does so
fresh material descends from the hopper, so that the retort remains permanently
filled, and its walls remain in contact with a heat-absorbing substance.
The products of the distillation are thus enabled to pass off through the dis-
charge pipe e without coming into contact with the naked red hot walls.
When the distillation is complete, the resulting charcoal is discharged by
opening the door c. After re-closing the latter, fresh material can then again be
re-charged through the hopper feed-door d.
In the arrangement shewn in Fig. 2, the hopper instead of being inserted
directly into the flanged rim, surrounding the mouth of the retort, is placed
in the flanged rim 62 of an intermediate annular piece which is inserted into
the rim of the retort mouth. In this case the discharge pipe e is on the
intermediate piece b¹.
In the arrangement shewn in Fig. 3, an upwardly tapering (conical) hopper
is employed in connection with the supporting piece, instead of the cylindrical
one. Here the retort is discharged through the mouth, for which purpose the
hopper is lifted off with, or without, the supporting piece.
In the arrangement shewn in Fig. 4, a horizontal retort a is provided with a
cylindrical hopper 6 inserted directly into the flanged rim of the mouth of the
retort.

page_text: Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. In the dry distillation of wood and kindred material, the employment of a
hopper or feed receptacle so arranged on the retort that as the shrinkage of the
charge takes place fresh material is constantly supplied for the purpose of pre-
venting the walls of the retort becoming over-heated, substantially as described.
2. For use in the dry distillation of wood and kindred material, apparatus
constructed and arranged substantially as herein before described with reference
to the annexed drawings.
Dated this 2nd day of October 1899.
ERNEST DE PASS,
Chartered Patent Agent,
78, Fleet Street, London, & 5A, Market Street, Nottingham,
Agent for the Applicant.