A Process of and Apparatus for Obtaining Ammonia and its Salts from the Spent Liquor of Molasses in Sugar Factories and from Vinasse.
Year: 1899

page_text: Date of Application, 2nd Aug., 1899-Accepted, 28th Oct., 1899
A Process of and Apparatus for Obtaining Ammonia and its Salts from
the Spent Liquor of Molasses in Sugar Factories and from Vinasse.
I, HEINRICH FISCHER, of Pecek, Bohemia, in the Empire of Austria, Managing
Director, 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:-
The process is based on the well known fact that thickened vinasse or waste-
liquor from sugar and spirit industries, when submitted to dry distillation, yield
their nitrogen in the form of ammonia and ammonia-salts, providing the distilling
temperature does not exceed 600° C.
The processes based on this fact as heretofore in use for obtaining the by-
products never came into general practice or use on account of their complicated
nature, unsafe working and defective products.
The improved process is characterized by the correct evaporation and gasification
of the vinasse, complete degasifying of the anhydrous vinasse by constantly
agitating it while gradually raising the temperature to a point not exceed-
ing 500° C. rational heating of the kiln with gas from the vinasse and by the easy
obtention of calcinated vinasse together with the ammonia-products.
The process is as follows:
The vinasse or waste-liquor which has been rendered thick by evaporation or
by the action of carbonic-acid and freed from lime, strontium or baryta in the
usual manner is introduced in the evaporating chamber of the kiln into vessels
provided with an agitator and heated by the hot gases from the distillation
chamber and is then evaporated to nearly complete anhydrous concentration
without exceeding a temperature of 200° C. The concentrated vinasse is then
passed through a conduit furnished with a heating jacket and into gasifying
retort proper. The retorts are of channel form and are provided with an agitating
screw. This latter by a simple device can be transformed into a conveyor-screw,
but during the mixing operation it is caused to slowly make a revolution first in
the one and then in the other direction and so effectually and continuously to
keep the vinasse agitated during the gasifying operation.
The retorts are formed in batteries in a kiln according to the amount of vinasse
to be treated. The retorts at starting are heated by means of coal but as soon as
the kiln produces continuous current of gas the latter is used as the heating
agent. Each retort is provided with a separate gas furnace with regulating slide
or valve for the gas and air enabling the temperature in the interior of the retort
to be elevated to any desired degree. The temperature is allowed to rise slowly
from 200° C. to 500° C. The operation is watched by taking samples from time
to time from the retort, and at the end of the operation when the sample
proves the gasification to be complete, the retort is discharged. To this end the
agitating screw is caused to rotate in one direction only and thus acts as a conveyor-
screw for discharging the retort after having previously opened the slide door
of the same. After having discharged the retort it is re-charged with vinasse
as before and the process repeated.

page_text: The gases evolved from the vinasse during the evaporation and distillation are
driven either by its own pressure or by means of an exhauster into a receiver
where the largest portion of the tar collects. From this receiver the gases pass
through tube-condensers similar to those in use in connection with coke-kilns for
the extraction of ammonia, and after separating out the largest portion of the
distillation products they pass into the gasometer from which separate pipes lead to
the gas furnaces of the retorts.
In this manner fine calcinated vinasse is obtained possessing sufficient temper-
ature to burn to white ash on the heap, beyond this there is obtained about 4% of
ammoniacal liquor together with the usual products of distillation, tar and nicely
burning highly heatgiving gas. The ammoniacal liquor is collected in reservoirs
filtered and is then treated for ammonia, or salts, in the ordinary manner.
tar mixed, with coal-dust forms an excellent combustible. The combustion gases
from the retorts pass underneath the evaporating vessels and thence into the
chimney.
The
The chief consideration in this process is the correct maintenance of temperature,
not exceeding 5000 C. together with constant and thorough stirring of the material
as on this depends the fullest possible yield in ammonia-products. At higher
temperature complex products of distillation are formed while ammonia decom-
poses and forms nitrogen and. at a still higher temperature it forms cyanogen.
A convenient apparatus for carrying out the above process is shown in the
accompanying drawings, in which:
Figure 1 is a front-elevation, partly in section on the lines A-B and C—D of
Figure 2.
Figure 2 is a longitudinal section of the apparatus, and
Figure 3 is an elevation of the reversing gear for the agitator.
The gutter like retorts 1 are combined in the form of a battery of a certain
number in one kiln and each retort is provided with a conveyor-screw 2. The
retorts are advantageously closed permanently at one end and are furnished at
their other and open end with a door 3 operated by a toothed pinion 4 and rack 5.
At this end also is provided a pyrometer 6 for ascertaining the temperatures.
Below each retort is a primary furnace 7 by which the retorts are first heated
till enough gas has been produced from the distillation to serve in heating the
retorts. For this purpose a gas supply pipe 8 in connection with the gasometer
is arranged along the front of the kiln and from this general supply pipe a separate
branch-pipe leads into the nozzle 9 and is adapted to be closed by a valve 10.
The Has
hearth consists of a channel 11 of refractory clay and having a number of
openings 12 for the gas jets. The air for combustion enters through a regulated
slide 13. The combustion products pass along the flue 14 and thence through
flue 15 into the chimney. In order to allow of anyone of the retorts being dis-
connected for discharging or other purposes a damper or slide 16 is so disposed as
to close the flue 14 from the main flue 15.
The gases evolved by this dry distillation pass, either under their own pressure
or through the action of an exhauster, along a pipe 17 into a receiver 18 where
the tar separates while the remaining gases pass through a pipe 19 into the
condenser from which only the gases for combustion are allowed to pass into the
gasometer.
With a view of completely utilizing the combustion products it is advantageous
to build the evaporating vessels 20 into the flue 15 as shown so as to evaporate
the vinasse.
The motion for the screw, a reciprocating rotary, or a continuous motion, may
be obtained by means of any known contrivance but for completeness of the
specification the mechanism shown in Figure 3 has been adopted. This mechanism
consists of a worm wheel 21 keyed on the shaft of the screw 2 and actuated by a
worm 22.
On the shaft of this worm are mounted a fast pulley 23 and two loose
pulleys 24, 25 supplied with a straight and with a crossed belt adapted to be
shifted by a belt shifting fork 26. The shifting fork is advantageously operated

page_text: through the intervention of a compressed air piston moving in a cylinder supplied
alternately from the right and from the left with compressed air. The reversing
operation for the piston is effected by a three way cock 27 the operating lever 28
of which is in the path of a tapper 29 provided on the worm wheel which on being
revolved reverses the cock valve 27 and causes the compressed air which enters
at 30 to pass through the one or the other branch 32 to the cylinder 31 which
exhausts into the atmosphere.
When it is desired to provide a continuous rotation for the conveyor screw 2 it
suffices to remove the lever 28 of the cock lever 27 from the path of the
tappet 29.
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:
1. The process for obtaining ammonia and its salts from the spent liquor or
molasses in sugar manufactories and from the vinasse of spirit distilleries,
characterized in that the liquor or vinasse in a nearly complete anhydrous condition
is submitted to dry distillation in retorts, preferably heated by a gas furnace,
at a temperature of 500° C. by constantly stirring it, the gases thereby evolved
(distillation products) being decomposed in receivers and condensers into useful
chemical products (tar, ammonia compounds) and into combustible heating
gases.
2. An apparatus for carrying out the process claimed in Claim 1, consisting
of a retort kiln fitted with evaporating vessels and characterized by retorts adapted
to be heated by the gases obtained by this process and provided with a combined
agitator and conveying screw 2 disposed in the gutter like portion of the retort
and operated by means of an automatic reversing gear in such a manner as to
impart to the said screw either a reciprocating rotation for stirring and agitation,
or a continuous rotation at the completion of the process for discharging the
retort.
Taad 41: 1 f
1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, 'London, W.C.,
Agents for the Applicant.