A Process for the Extraction of Distillation Products from Sawdust, Wood Waste, and the like.
Year: 1895

page_text: Date of Application, 28th June, 1895-Accepted, 24th Aug.. 1895
COMPLETE SPECIFICATION.
A Process for the Extraction of Distillation Products from Sawdust,
Wood Waste, and the like.
1, FRANZ JOSEF BERGMANN, of Neheim on the Ruhr, in the Kingdom of
Prussia, and German Empire, Engineer, do hereby declare the nature of this
invention and in what mauner the same is to be performed, to be particularly
described and ascertained in and by the following statement, that is to say:-
My invention relates to a process for the extraction of distillation products from
saw dust, wood waste, and the like.
The extraction of vinegar by the distillation of wood waste and sawdust not
having heretofore proved remunerative, I have adopted a process which consists in
pressing the wood in powerful presses so as to remove from it the greater part of
the moisture it contains prior to distilling it, instead of in carbonising the sawdust
in retorts directly, as has been usual up to the present time.
I am thus able to obtain vinegar in which the proportion of water is far less
than it would be had the wood waste not been previously compressed.
In carrying out the process heretofore usually employed in extracting vinegar
from dry wood, it has been found that such vinegar contained a very considerable
The obtainment of highly
proportion of water, in fact as much as 80 per cent.
concentrated vinegar therefore presented considerable difficulty, in as much as
vinegar and water have very nearly the same boiling point. As therefore the
separation of water cannot be effected by evaporation, it has been necessary to
extract the acid contained in the diluted solution by means of lime, and in a
subsequent stage to eliminate the acetic acid from the acetate of lime by means of
sulphuric acid or hydrochloric acid.
Now, according to my invention, to obtain high grade acetic acid from wood (in the
condition of dust or chips), I extract the water therefrom by subjecting it to a
preliminary mechanical treatment. Even very dry wood, invariably contains
about 15 per cent. of water, which, by the present process, may be removed from
the wood waste. Where wood in the condition of sawdust, or in small chips or
particles, is not directly available, it should preferably be first converted into such
condition. The sawdust, or the like, is then made up into solid form and
dehydrated. This is conveniently effected by means of a press in which the wood
waste is compressed sufficiently to increase its specific gravity to double that of
natural wood. The cylinder and piston of the press are provided with orifices
covered with felt, through which, during the operation of the process, the water
may escape, without, however, the particles of wood being allowed to leave
the press.
As the pressure gradually increases-300 atmospheres being the maximum it
should attain, a considerable heat developes, so that the water escapes from the
apertures in question in the condition of steam. By this means, blocks or briquettes
of wood are forined, the proportion of moisture contained being smaller the higher
the pressure to which the saw dust has been submitted.
In order to provide discharge channels between the several briquettes throughout
the length of the retort during the process of distillation, each individual briquette
should preferably be furnished with apertures and projections. For this purpose,
the press may be provided with a suitably arranged cylinder, its piston, for
example, being fitted with pins or studs, while the cylinder bottom is correspondingly
perforated so that the said pins or studs may pass through the perforations after

page_text: having perforated the material made into briquettes. For the formation of the
projections, there may be provided recesses or cut away portions in the cylinder
bottom. The details of construction of the press are immaterial, the main object
being that the briquettes should be, as far as possible, free from moisture.
The briquettes obtained in this way are packed in suitable retorts and carbonised.
Owing to the provision of the projections above mentioned, there will then be formed,
between the several briquettes, discharge channels, while the perforations will
constitute convenient channels for the circulation of air or gas throughout the
length of the retort.
The gases, such as acetic acid, tar, or turpentine, which are developed, pass
through the discharge pipe of the retort into the cooling apparatus where the are
precipitated separately in the well known manner. Gases which cannot be condensed
are carried off by a separate pipe or fine.
The process hereindescribed enables the utilization of the wood shavings,
saw dust, and wood waste generally, which collects in saw-mills and the like.
Previous attempts to directly carbonise sawdust have produced unsatisfactory
results, if only for the reason that the retorts had to be charged too often, and that
the gases could only escape with great difficulty from the retorts.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
The process for the extraction of high grade distillation products from sawdust,
wood-waste, and the like, consisting in converting such wood into blocks or briquettes,
by subjecting them, in suitable presses, to a pressure sufficient to impart to them
double the specific gravity of natural wood, and finally carbonising the product in
suitable retorts, substantially as set forth.
T 100-
ERNEST DE PASS,
Chartered Patent Agent,
78, Fleet Street, London, and 5ª Market Street, Nottingham,
Agent for the Applicant.