Note: Descriptions are shown in the official language in which they were submitted.
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The invention is concerned with a process and equipment
for the separation of/asphalts and oils which form the residue
from vacuum distillation of petroleum; this process may also
be advantageously applied to the purification and reclaiming
of lubricant oils recovered from used mineral oils, called
drain oils.
The process according to the invention is founded on
the known capacity of liquid propane to dissol~e, in the form~
of a selective solvent, the hydrocarbon fraction from which
lubricant oils are formed, resulting in the separation and
precipatition of asphalts and other non-dissolved particles
which make up the material subjected to the treatment.
This property of propane has already been applied in
different processes which have been put into effect in
modern petroleum refineries for the production of basic
lubricant oils and asphalts from the residue f~Qmv~u~
distillation, but the complicated and costly equipment for
de-asphalting units of this type is only profitable for the
treatment of considerable quantities of residue, and is not
economic on the general scale for plant for the purification
and reclaiming of used oils, the capacity of which in practice
does not exceed a few metric tonnes per day.
The object of this invention is to ensure the production
of basic lubricant oils from the residue from vacuum distillat-
ion of petroleum, and, in particular, the de-asphalting and
purification of lubricant oils from used mineral drain oils,
by proposing a process capable of being put into operation
on a small scale, with the use of simple and inexpensive
equipment.
In large reactors, used in plants for the de-asphalting of
residues from vacuum distillation of petroleum, separation
of the asphalts and the lubricant oils is effected by simply
mixing a specified amount of heavy hydrocarbons which have
been introduced into the liquid propane, which dissolves the
fraction of the lubricant oils and causes the heavier particles
of hydrocarbons and other non-dissolved compounds to precipitate ~ :
to the bottom of the reactor, whilst the liquid propane, laden
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with the dissolved lubricants, being lighter, again rises to
the top of the reactor, where the apparatus producing the
variations in temperature facilitates this upward motion,
and also the continous evacuation of the mixture, for the sub-
sequent separation of the oil and its solvent, propane, then
recycled the system in the liquid state.
Since the aim of this invention is to limit, as far as
possible, the volume of equipment and to treat on an economic
basis even small quantities of material containing lubricant
oils, asphalts, carbons, and other impurities, such as
mineral or meta~lic dusts, for example, which are found in
suspension in the used drain oils, it is necessary to provide
for means of improving the facilities of contact between the
fractions of lubricant oils and their selective solvent,
(propane), and also means of allowing acceleration of accurate
and rapid separation of the dissolved lubricant and other
materials, non-dissolved, and their precipitation.
The object of the invention is then a process for the
production of basic mineral oils and of residual asphalts
obtained either from the residue f~om~v,acuum distillation
of petroleum, or from used drain oils, this process being
of the type in which the material to be treated is placed
in contact with a requisite amount of liquid propane which
dissolves the fraction of oil capable of being used as
lubricant, whilst the fraction of hydrocarbons and of other
non-dissolved materials separates off and hastens, accurately
and rapidly, separation of the dissolved oils and/propane
being then obtained by vaporization of the propane, this
process being characterized by the fact that, to ensure
excellent contact between the oil and the propane, its selective
solvent, and to obtain accurate separation and rapid precipit-
ation of the asphalts and other non-dissolved materials, the
treated material is injected through a pump, suitably adapted
to carry out pulsed injections, at an appropriate rate and
under the requisite pressure to make the treated material
penetrate the extraction area, where the pressure is maintained
at an adequate level in relation to the given temperature for
the propane to be kept in a liquid state. The pulsed in;ections
of the treated material into the liquid propane are carried
out through a spraying device which causes dispersion of the
material in the form of fine droplets, facilitating the
dissolution of the fraction of lubricant oil~i in the propane,
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and the separation and also the precipitation of the non-
dissolved fractions of the asphalts, etc. ... a great n~
of which have already deposited at the bottom of the extraction
area.
The object of the invention is also a process for
concentrating the dissolved lubricant, allowing it to be
separated off from part of the liquid propane, characterized
by the fact that the liquid propane forms a reflux at the head
of the concentration area, from which a pump recycles it by
pulsed injections starting at the head of the first column,
against theflow of the treated material continously introduced
into this column from the extraction area, which results in
the rapid liberation of all the dissolved lubricant and in the
precipitation of the asphalts and of the other insoluble
particles in the propane.
The application to the processes outlined above of
vibrations transmitted to the whole unit, either by an approp-
riate assembly of the compressor when it is a question of a
small-capacity plant, which is specially designed for the scrub-
bing and reclaiming of drain oils, for example, or by apparatus
fulfilling the same office in larger units, which are designed
for the treatment of residue from vacuum distillation of
petroleum, i8 also one object of this invention, since the
effect of these vibrations noticeably improves the output,
both in $he part of the equipment operating under high pressure
where the separation and precipitation of non-soluble particles
in propane takes place, and in the part of the epuipment -~
operating under low pressure and/or under vacuum where the
separation of the propane and the purified lubricant take
place, by vaporization of the propane which, after having been
pressurized and condensed, is recycled in the liquid state in
the system.
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The equipment used for the application of the processes
which have just been briefly described are also objects of the
invention.
One form of application of the invention will be described
below, as a non-restrictive example, reference being made to
the attached diagram, which is a plan of a unit which conforms
with the invention.
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The residue from vacuum distillation of petroleum or
used mineral drain oil, coming from tank 1, is introduced
by motorized pump 2, which has been adapted to effect pulsed
transfer through line 3 into extraction area 4 in which the
requisite quantity of liquid propane is simultaneously
introduced by line 5. As indicated above, the material to
be treated is injected through a spraying device into this
area, so as to ensure excellent contact with the liquid
- propane, which dissolves the soluble particles of lubricant,
thus facilitating the separation and precipitation of the
asphalts and other insoluble particles, which begin to pre-
cipitate towards the bottom of this extraction area.
; This insoluble residue can be periodically evacuated from
the system by pressure to tank 6 by line 7, whilst the partially
scrubbed mixture of oil and propane is transferred by a siphon
and line 8 to the area of the concentration system in which
final scrubbing of the dissolved lubricant takes place, com-
posed of three columns, 9, 10 and 11, in which separation
of the liquid propane occurs, forming a reflux at the head
of these columns composed of liquid propane and a small
quantity of the lightest lubricant hydrocarbons of the batch
treated. Motorized pump 12 draws this reflux through line 13
at the head of column 11, continuously transferring it by
means of pulsed injections through the perforated line 14 :
~; against the flow of the partially scrubbed mixture, also
continuously introduced into the first column of concentration
:~ area 9. The vibrations caused by the pulsed reflux injections,
as well as those transmitted to the whole plant, are doubtless
the main reason for the phenomenon of the formation of the
. reflux in this system, operating at an appropriate pressure
to keep the propane in the liquid state at a given temperature.
The result of this pulsed and continous passing of reflux is
the rapid and accurate precipitation of all the molecules
of hydrocarbons and other non-dissolved impu~ities in the
propane, which pour off towards the bottom of columns 9 and
. 10. The mixture of oil and propane, now greatly purified,
is transferred through line 15, which is perforated, to within
column 10; this pure mixture then passes through line 16 into
; the third column, 11, of the concentration system, whence the
~ mixture of oil and propane is introduced through the siphon
and line 17 into a system of dry filters 18. At the entrance
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to this filter system, the control valves no longer monitor
the high pressure, and the expansion of the vaporizing propane
commences. Vaporization of the propane, passing to the
gaseous state, causes a sufficlent drop in temperature in the
filter cylinders to eliminate all traces of any humidity pos-
sibly contained in the mixture. The mixture of oll and propane
then flows through line 19 into evaporator coil 20, which is
heated by heat-exchange with propane gas passing through a
similar coil 21, which conveys it from heated tank 22 to
compressor 23 by line 5 for compression, condensation and re-
cycling in the extraction area in the liquid state. The clean
oil, now separated from its solvent, propane, is withdrawn
periodically or continously into 24. The asphalts and other
residual products are periodically sent by pressure from the
system at the bottom of areas 4, 9, 10 and 11 through line 7
to heated tank 6, from which the propane gas is drawn up by
the compressor through line 25, to be recycled in the liquid
state by line 5 in the extraction area, whil~t the asphalts
and other reæidues are evacuated through 26. The volume of
propane in the system can be made up from reserves, 27, by
line 28, which brings it to the compressor to be ~ f~
and introduced into the system.
An advantageous form of arrangement of this type of
apparatus, particularly for a unit treating small quantities
of material, is for the unit to be assembled on a rigid
platform, for example, on four legs and on two levels. The
motorized compressor is fixed to the floor of the second
level and transmits its vibrations to the entire plant.
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