U.S. patent application number 14/783985 was filed with the patent office on 2016-03-10 for process for treating a hydrocarbon-based heavy residue.
This patent application is currently assigned to ENI S.p.A.. The applicant listed for this patent is ENI S.p.A.. Invention is credited to Giuseppe BELMONTE, Alberto Maria Antonio MALANDRINO, Vincenzo PICCOLO.
Application Number | 20160068760 14/783985 |
Document ID | / |
Family ID | 48794153 |
Filed Date | 2016-03-10 |
United States Patent
Application |
20160068760 |
Kind Code |
A1 |
BELMONTE; Giuseppe ; et
al. |
March 10, 2016 |
PROCESS FOR TREATING A HYDROCARBON-BASED HEAVY RESIDUE
Abstract
The process for treating a hydrocarbon-based heavy residue (1),
in particular bituminous residues with a high asphaltene content,
comprises the following operations: A) bringing the heavy residue
to be treated to a temperature within the range of 325-500.degree.
C.; B) subjecting the heavy residue to be treated to a
substantially adiabatic expansion in an environment at a pressure
equal to or lower than about 0.1 bara, and at a temperature equal
to or lower than 450.degree. C., so as to separate, from the heavy
residue to be treated, a first less volatile fraction (17) having a
boiling point at atmospheric pressure equal to or higher than
540.degree. C. and whose solid and/or anhydrous residue prevalently
contains asphaltenes insoluble in pentane and/or other residues
insoluble in tetrahydrofuran. It allows a more effective flushing,
and also to actuate the process in an extremely simple plant and
without centrifugations.
Inventors: |
BELMONTE; Giuseppe; (Milano,
IT) ; MALANDRINO; Alberto Maria Antonio; (Milano,
IT) ; PICCOLO; Vincenzo; (Zelo Buon Persico (MI),
IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ENI S.p.A. |
Roma |
|
IT |
|
|
Assignee: |
ENI S.p.A.
Roma
IT
|
Family ID: |
48794153 |
Appl. No.: |
14/783985 |
Filed: |
April 22, 2013 |
PCT Filed: |
April 22, 2013 |
PCT NO: |
PCT/IT2013/000115 |
371 Date: |
October 12, 2015 |
Current U.S.
Class: |
208/108 ;
208/107; 208/363; 208/366 |
Current CPC
Class: |
C10C 3/06 20130101; C10G
67/02 20130101; C08L 95/00 20130101; C10G 2300/206 20130101; C10G
2300/301 20130101; C10G 7/06 20130101; C10G 47/30 20130101; C10G
49/12 20130101; C10G 7/12 20130101; C10G 2300/107 20130101; C10G
49/04 20130101; C10G 2400/16 20130101; C10G 31/06 20130101; C10G
2300/1077 20130101 |
International
Class: |
C10G 7/06 20060101
C10G007/06; C10G 67/02 20060101 C10G067/02 |
Claims
1. A process for treating a heavy hydrocarbon-based residue,
comprising: bringing the heavy hydrocarbon-based residue to a
temperature of 325-500.degree. C.; subjecting the heavy
hydrocarbon-based residue to a substantially adiabatic expansion in
an environment having a pressure equal to or lower than about 0.1
bara and at a temperature equal to or lower than 450.degree. C. to
separate a first less volatile fraction and a second more volatile
fraction from the heavy hydrocarbon-based residue; wherein: the
first less volatile fraction has a boiling point of equal to or
higher than 540.degree. C. at atmospheric pressure and comprises a
solid and/or an anhydrous residue comprising asphaltenes insoluble
in pentane; and optionally other residues insoluble in
tetrahydrofuran; and the second more volatile fraction comprising
maltenes and other hydrocarbons having a boiling point equal to or
lower than 540.degree. C. at atmospheric pressure.
2. The process according to claim 1, wherein the heavy
hydrocarbon-based residue is a bituminous residue comprising 20% to
45% by weight of C5-asphaltenes and 10% to 20% by weight of
tetrahydrofurans.
3. The process according to claim 1, further comprising: expanding
the heavy hydrocarbon-based residue starting from a pressure of
higher than 1 bara.
4. The process according to claim 3, wherein the heavy
hydrocarbon-based residue is expanded starting from a pressure of
1-2 bara.
5. The process according to claim 1, wherein the adiabatic
expansion is substantially instantaneous.
6. The process according to claim 1, further comprising: effecting
the adiabatic expansion by passing the hydrocarbon-based residue
through a lamination valve.
7. The process according to claim 1, wherein the heavy
hydrocarbon-based residue comprises at least 30% by weight of
asphaltenes insoluble in pentane and optionally other residues
insoluble in pentane and/or tetrahydrofuran.
8. The process according to claim 7, wherein the heavy
hydrocarbon-based residue comprises 20% to 45% by weight of
C5-asphaltenes and 10% to 20% by weight of tetrahydrofurans.
9. The process according to claim 1, wherein the first less
volatile fraction has a total content of asphaltenes of 75% to 94%
by weight and a total content of maltenes and other lighter
hydrocarbons of 6% to 25% by weight.
10. The process according to claim 1, further comprising: obtaining
the heavy hydrocarbon-based residue to be treated by converting
heavy oils into lower-molecular-weight substances, subjecting the
heavy oils to hydrocracking optionally in the presence of
catalysts.
11. The process according to claim 10, wherein the hydrocracking is
effected by bubbling hydrogen into the heavy oils or other
hydrocarbon-based substances.
12. The process according to claim 1, further comprising:
fluidifying the heavy hydrocarbon-based residue by introducing a
stream of water vapor or other gaseous substance into the heavy
hydrocarbon-based residue.
13. The process according to claim 12, wherein the ratio between
the water vapor or the other gaseous substance and the flow-rate of
the heavy hydrocarbon-based residue is 0.03 to 0.75 by volume.
14. The process according to claim 1, further comprising: effecting
the substantially adiabatic expansion in a separator comprising a
container, and collecting, on the bottom of said container, the
first less volatile fraction.
15. The process according to claim 1, further comprising:
depositing the first less volatile fraction on a cooled conveyor
belt having a surface temperature of equal to or lower than
100.degree. C.
16. The process according to claim 15, further comprising:
solidifying and optionally reducing the first less volatile
fraction to granules through cooling by contact with the cooled
conveyor belt.
17. The process according to claim 1, being a continuous process.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a process for treating a
hydrocarbon-based residue.
[0002] The process and plant according to the invention are
particularly suitable for treating and facilitating the use,
management and disposal of hydrocarbon-based residues, in
particular bituminous residues with a high asphaltene content,
obtained as by-product in a previous conversion process of organic
residues with a high molecular weight or in any case a high C/H
ratio, such as, for example, oils or more generally heavy
hydrocarbons, distillation residues possibly already partly
deasphalted, bitumens from tar sands, oils deriving from coal and
oil shales.
STATE OF THE ART
[0003] Conversion methods of high-molecular-weight organic
residues, such as for example, heavy oils such as distillation
residues possibly already partly deasphalted, oils from tar sands,
oils deriving from coal and oil shales, are currently known. The
conversion is effected by reducing the molecular weight of the
residues to be treated, and increasing their H/C ratio. Examples of
conversion methods that combine cracking and hydrogenation
reactions of the reactive fragments in the presence of catalysts
are described in documents U.S. Pat. No. 5,932,090, EP2158304,
EP2155835, EP2291238.
[0004] An extremely dense bituminous residue is obtained as
by-product from the conversion, which, under standard conditions,
has the consistency of a viscous paste and is therefore extremely
difficult to manage for transportation, sale, disposal or possible
re-use on the same production site. This bituminous residue
contains an organic fraction normally having an even higher
molecular weight, and an even more consistent fraction of coke and
inorganic compounds with respect to the residue entering the
catalytic hydrocracking process.
[0005] The content of coke and inorganic residues forms THFis, i.e.
the fraction of material insoluble in tetrahydrofuran.
[0006] The bituminous residue is produced in considerable
quantities: in a petrochemical plant capable of refining 200,000
barrels/day of crude oil, for example, the relative conversion
plant of the organic residues by means of catalytic hydrocracking
is capable of producing 60,000 barrels/day.
[0007] It would therefore be convenient to convert the bituminous
residue into higher-quality products that can be re-used, for
example, as combustibles or commercial fuels, or into an inert
product that is easier to manage, dispose of and is less harmful
for the environment.
[0008] U.S. Pat. No. 3,928,170 describes a process (called EUREKA
process) for the production of a pitch by means of thermal cracking
in a stream of vapour of a bottom oil residue at a pressure within
the range of 1.1-3 barg and a temperature in the reaction area of
350-450.degree. C.; the reactor is preceded by a furnace, for
preheating the charge, and is followed by a separation section of
the products. The pitch is extracted from the bottom of the
cracking reactor which operates in semibatch to avoid the formation
of coke during the preheating phase. This process however is not
satisfactory for treating bottom residues with a particularly high
concentration of asphaltenes or residues insoluble in
tetrahydrofuran.
[0009] U.S. Pat. No. 4,477,334 describes a process in which heavy
hydrocarbons can be converted in a continuous cracking process,
without the formation of coke, forming a pitch as by-product. The
solvent deasphalting process uses a solvent (generally propane or
butane) under conditions close to those critical for separating the
maltene component from the asphaltene component: the asphaltene
fraction (which can also contain a certain percentage of solids) is
recycled to the process, whereas the maltene fraction (rich in DAO,
DeAsphalted Oils), after separating the solvent by extraction under
a supercritical condition, forms a product. In the case in question
of the production of a concentrated pitch, this process represents
the opposite of solvent deasphalting as it is the asphaltene
component (rich in solid phase) that is to be extracted and the
maltene component recycled.
[0010] The difficulty in applying this process consists in the use
of more columns for managing the cycle of the solvent under
supercritical conditions.
[0011] One of the limitations of the centrifugation is the maximum
operating temperature that cannot exceed 150.degree. C. Under these
conditions there may be problems relating to the movement and
discharging of the concentrated stream, whereas the light phase,
which is recycled to the reaction section, is still rich in
asphaltene components which jeopardize the performances of the
conversion plant.
[0012] An objective of the present invention is therefore to
overcome the above-mentioned drawbacks of the state of the art, in
particular by providing a process for converting the bituminous and
pasty residue of previous conversion processes of
high-molecular-weight organic residues, into products that can be
more easily and conveniently re-used and disposed of.
SUMMARY OF THE INVENTION
[0013] According to the invention, this objective is achieved with
a process having the characteristics according to claim 1.
[0014] Further characteristics of the invention are object of the
dependent claims.
[0015] The advantages that can be obtained with the present
invention will appear more evident, to experts in the field, from
the following detailed description of a particular non-limiting
embodiment, illustrated with reference to the enclosed schematic
figures.
LIST OF FIGURES
[0016] FIG. 1 shows the scheme of a process for treating bituminous
residues according to a particular embodiment of the invention;
[0017] FIG. 2 shows a scheme of the ejector of the plant of FIG.
1.
DETAILED DESCRIPTION
[0018] In the present description, the expression "compound X
prevalently containing the substance Y" unless otherwise specified
should be interpreted as meaning that the compound X contains at
least 50% by weight of the substance Y.
[0019] FIGS. 1, 2 relate to a plant for treating a pitchy or
bituminous residue obtained as by-product of a conversion process
of organic residues having a high molecular weight or in any case a
high C/H ratio, such as for example, heavy oils such as
distillation residues possibly already partly deasphalted, bitumens
from tar sands, oils deriving from coal and oil shales.
[0020] Said plant is indicated with the overall reference number
100. The reference number 1 indicates a feeding stream which is
preferably a blow-down coming for example from the vacuum
distillation column of a conversion plant of heavy oils described
for example in the documents U.S. Pat. No. 5,932,090, EP2158304,
EP2155835, EP2291238, or from other conversion processes of heavy
oils by means of ebullated bed catalytic hydrocracking or other
cracking processes. The blow-down of the feeding stream 1 is a
solid-liquid suspension, viscous but pumpable at suitable
temperatures.
[0021] The content of C5 asphaltenes (asphaltenes insoluble in
n-pentane) in said feeding stream (1) ranges from 20 to 45%,
whereas the THFis range from 10 to 20%.
[0022] The catalyst of the possible conversion process by means of
hydrocracking can, for example, be based on one or more transition
metals such as Ni, Co, Mo, preferably molybdenum.
[0023] The feeding stream 1 can have a temperature ranging for
example from 320-350.degree. C., and more preferably
320-330.degree. C., in order to facilitate the pumpability of the
fluid. Before entering the furnace 3, the stream 1 is preferably
heated and fluidified by introducing overheated water vapour 2, for
example a vapour flow-rate at about 350.degree. C. The introduction
of water vapour also prevents the formation of coke in the
furnace.
[0024] The water vapour flow-rate preferably ranges from 0.5-2% by
weight of the flow-rate of the blow-down 1 before being introduced,
and preferably about 1% by weight of the blow-down flow-rate.
[0025] The feeding stream 1' is preferably subsequently further
heated to about 325-500.degree. C. by introducing it, for example,
into the furnace 3. The temperature of the stream 4, immediately
before being introduced into the separator 6, can be substantially
the same as that inside the furnace 3, and is preferably equal to
or lower than 480.degree. C. The stream 4 can for example be a
three-phase solid-liquid-vapour stream.
[0026] In the furnace 3, there is preferably a pressure higher than
atmospheric pressure, more preferably ranging from 1-2 bara and
even more preferably from 1.3-2 bara.
[0027] This pressure is preferably the same as the stream 4
immediately before undergoing the adiabatic expansion described
hereunder.
[0028] In the present description, the pressure values, unless
otherwise specified, should be considered as being absolute
pressure values and not relating to atmospheric pressure.
[0029] According to an aspect of the invention, the stream 4
leaving the furnace 3 is subjected to a substantially adiabatic
expansion in an environment at a pressure equal to or lower than
about 0.1 bara and at a temperature equal to or lower than
450.degree. C. in order to separate a first less volatile fraction
17, having a boiling point at atmospheric pressure equal to or
higher than 540.degree. C. and whose solid and/or anhydrous residue
prevalently contains asphaltenes insoluble in pentane and/or other
residues insoluble in tetrahydrofuran, from the heavy residue to be
treated.
[0030] A second more volatile fraction 7, prevalently composed of
maltenes and other hydrocarbons having a boiling point equal to or
lower than 540.degree. C. at atmospheric pressure, is also
preferably separated from the heavy residue.
[0031] The substantially adiabatic expansion is preferably effected
by means of substantially instantaneous expansion (flash) through a
lamination valve. The adiabatic expansion preferably takes place in
a first separator 6 comprising a sealed container, in which there
is the above pressure equal to or lower than 0.1 bara. More
preferably, there is a pressure equal to or lower than 0.04 bara in
the separator 6.
[0032] The above-mentioned maximum temperature of 450.degree. C. is
an average value over the whole volume of the separator 6. The
stream 4 is preferably subjected to a substantially adiabatic
expansion in an environment at a temperature equal to or lower than
400.degree. C., and more preferably equal to or lower than
390.degree. C.
[0033] The flash or in any case adiabatic expansion advantageously
takes place in the upper part of the sealed container or in any
case in the first separator 6, whereas a stripping stream 5,
preferably a stream of water vapour, is introduced into its lower
part.
[0034] Depending on the operating conditions (stripping vapour
flow-rate 5 and/or temperature of the flash chamber 6), the
asphaltene-THFi fraction in the heavy stream can vary from 75 to
94%.
[0035] The ratio between the stripping vapour 5 and blow-down
flow-rate 1 ranges from 0.03 to 0.75, more preferably from 0.03 to
0.5.
[0036] The second more volatile fraction 7 together with most of
the stripping stream 5, is preferably evacuated from the first
separator 6 reaching the ejector 8. The ejector 8 is advantageously
of the type of FIG. 2, i.e. equipped with a Venturi tube which
sucks the stream 7, introduced into the narrow section of the
Venturi tube, and expels it from the duct 8 depending on the
flow-rate of a suitable motor fluid 9, for example vapour, that
enters the Venturi tube from the duct 9'. It is therefore possible
to control the vacuum degree in the first separator 6 by acting on
the flow-rate of the motor fluid 9 entering the Venturi tube.
[0037] More preferably, it is possible to use a multistep ejector
system, depending on the vacuum degree to be obtained in the flash
chamber.
[0038] The stream 10, containing the second more volatile fraction
7, the stripping stream 5 and the motor fluid 9, is subsequently
cooled, for example by means of the heat exchanger 11--in order to
condense the heavier phases, and then reaches the second separator
13.
[0039] In order to obtain a more effective condensation, the
exchanger 11 operates at such a temperature that the stream 12
leaving it is preferably at 50.degree. C.
[0040] The second separator 13 separates the following products
from the stream 12: [0041] a first stream based on heavy
hydrocarbons 14, rich in deasphalted heavy oils (DAO), maltenes and
other hydrocarbons with a boiling point equal to or higher than
540.degree. C.; [0042] a second gaseous stream 15 based on lighter
hydrocarbons and having a boiling point lower than 540.degree. C.;
and [0043] a third stream 16, prevalently consisting of
condensation water.
[0044] The first stream 14 can be advantageously reintroduced into
the refining or conversion cycle of heavy oils upstream of the
plant 100, for example a vacuum distillation column. The second
gaseous stream can be sold, for example, as fuel, propellant or
another commercial product.
[0045] The gaseous stream 15, after leaving the condensation system
of the ejectors, can be sent to a blow-down.
[0046] The first less volatile fraction 17, enriched in asphaltenes
and poor in maltenes and other lighter hydrocarbons, practically
containing all the asphaltenes of the feedstock and having a
composition of maltenes and other lighter hydrocarbons varying from
6 to 25%, depending on the operative conditions, after being
collected on the bottom of the first separator 6, can be poured by
gravity, by means of an operating machine or repressurization lung,
onto a cooled conveyor belt 18 and cooled thereon and transformed
into a granular solid. After sudden cooling of the cooled belt 18
on the surface, the first less volatile fraction 17 solidifies very
rapidly and disintegrates. For this purpose, the surface of the
cooled conveyor belt 18 is preferably kept at a temperature equal
to or lower than about 100.degree. C., and more preferably equal to
or lower than about 50.degree. C.
[0047] Again for this purpose, the first less volatile fraction 17
is preferably deposited on the conveyor belt 18, or in any case
discharged from the separator 6, at a relatively high temperature,
for example equal to or higher than 315.degree. C. and even more
preferably from 315 to 480.degree. C.
[0048] These high temperatures facilitate the same discharge
operation. The reference number 19 indicates the solidified
bituminous residue, in the form of granules. As it is in the form
of granules rather than a paste or sludge, the bituminous residue
19 can be packaged directly, for example in metal barrels, and
commercialized, or in any case managed much more easily. The
granular bituminous residue can be used directly, for example, as
an inert product for road surfaces or as fuel for blast furnaces or
other industrial furnaces.
[0049] The combination of the adiabatic expansion, preferably flash
or in any case sufficiently rapid, and high vacuum degree of the
environment in which the expansion takes place, allows residues of
previous recovery treatment, having a particularly high content of
asphaltenes and inorganic compounds, to be treated, enabling their
extremely effective separation into a) a first fraction extremely
rich in maltenes, liquid or gaseous hydrocarbons and extremely poor
in asphaltenes and b) a second fraction solid at room temperature,
considerably enriched in asphaltenes and inorganic residues and
extremely poor in maltenes and liquid or gaseous hydrocarbons at
standard temperature and pressure.
[0050] More specifically, the process according to the invention is
particularly suitable for treating residual blow-down streams from
oil or hydrocarbon treatment processes, wherein said residues
contain at least 30% by weight, and even over 50% by weight, of
asphaltenes insoluble in pentane and/or other residues, not
necessarily organic, insoluble in tetrahydrofuran.
[0051] The heavy residue to be treated may preferably have a
content of C5-asphaltenes ranging from 20 to 45% by weight and a
THFi content ranging from 10 to 20% by weight.
[0052] The content of solids insoluble in tetrahydrofuran and
asphaltenes of the less volatile fraction 17 can easily reach and
constantly maintain very high concentrations, for example ranging
from 75% to 94% by weight, or in any case over 75% by weight. The
invention, on the other hand, allows the second more volatile
fraction 7 to become poorer in asphaltenes.
[0053] The separator 6 can comprise or consist of a vacuum column
from which the heavy fraction can be extracted from the bottom and
the light fraction laterally. A stream containing water vapour and
incondensable products is extracted from the head of the column,
which is sent to the ejector 8. The stream based on heavy
hydrocarbons 14, coming from the separation of the ejector 8, can
be joined with the side cut of the vacuum column (see paragraph
18).
[0054] The following results, obtained from a numerical simulation
referring to the plant 100 assuming that the separator 6 is a
container suitable for effecting a vacuum flash in a single
separation step, provide a better demonstration of the efficacy of
the separation obtainable with the invention.
Numerical Examples 1-8
[0055] In examples 1-4, the plant 100 was under the following
conditions:
a.1) pressure P6 in the separator 6: 0.02 bara; b.1) composition of
the feeding stream 1: [0056] hydrocarbons and in general a fraction
with a boiling point lower than 500.degree. C. (500--in the table):
8% by weight; [0057] hydrocarbons and in general a fraction with a
boiling point ranging from 500-540.degree. C. (500-540 in the
table): 14.2% by weight; [0058] hydrocarbons and in general a
fraction with a boiling point higher than 540.degree. C.,
substantially identifiable as the maltene fraction (540+ in the
table): 28.4% by weight; [0059] asphaltene fraction insoluble in
pentane (ASF-C5 in the table) but soluble in tetrahydrofuran: 29.4%
by weight; [0060] solid residue containing coke, other organic
and/or possible inorganic fraction such as for example metallic
sulfides and other catalytic residues insoluble in tetrahydrofuran
(THFis in the table): 20% by weight; d.1) temperature of the
overheated vapour 2 and stripping vapour 5: 350.degree. C.; e.1)
pressures of the overheated vapour 2: 4 bara; f.1) flow-rates of
the overheated vapour 2 and stripping vapour 5: 50 kg/h.
[0061] The following values were obtained on the plant 100 with the
previous parameters:
TABLE-US-00001 TABLE 1 Case 1 Case 2 Case 3 Case 4 Q1, kg/h 4643
4637 4641 4637 Q2 + Q5, kg/h 1000 1000 3000 3000 T3, .degree. C.
423 365 394 326 Thermal requirement 0.29 0.12 0.20 0.01 of furnace
3, MMKcal/h T6, .degree. C. 386 340 394 326 Q17 total, kg/h 2429
2927 2428 2927 % separated from Q1 52.3 63.1 52.3 63.1 Composition
of bottom product 17 [% by wt] 500- 0.6 0.19 0.04 0.13 500-540 0.37
1.37 0.29 1.12 540+ 5.75 20.30 5.66 20.60. ASF-C5 55.58 46.46 55.76
46.47. THFis 38.24 31.68 38.22 31.68 Q7, kg/h 3214 2709 5212 4709
Composition of stream 7 [% by wt] H.sub.2O 31..1 36.91 57.55 63.70
500- 11.51 13.49 7.10 7.80 500-540 20.23 22.88 12.51 13.32 540+
36.78 26.71 22.72 15.17 ASF-C5 0.37 0.02 0.12 0.01 THFis 0 0 0
0
[0062] In Examples 5-8, the plant 100 was under the following
conditions:
a.2) pressure P6 in the separator 6: 0.01 bara; b.2) composition of
the feeding stream 1: as in examples 1-4
[0063] The following values were obtained on the plant 100 with the
previous parameters:
TABLE-US-00002 TABLE 2 Case 5 Case 6 Case 7 Case 8 Q1, kg/h 4650
4637 4645 4637 Q2 + Q5, kg/h 1000 1000 3000 3000 T3, .degree. C.
479 415 459 383 Thermal requirement 0.45 0.26 0.39 0.17 of furnace
3, MMKcal/h T6, .degree. C. 437 385 402 354 Q17 total, kg/h 2430
2927 2429 2927 % separated from Q1 52.3 63.1 52.3 63.1 Composition
of bottom product 17 [% by wt] 500- 0.12 0.32 0.08 0.23 500-540
0.59 1.86 0.42 1.53 540+ 6.06 19.71 5.84 20.12 ASF-C5 54.96 46.42
55.39 46.45 THFis 38.27 31.68 38.24 31.68 Q7, kg/h 3220 2710 5216
4710 Composition of stream 7 [% in peso] H.sub.2O 31.05 36.90 57.52
63.70 500- 11.47 13.34 7.09 7.74 500-540 20.06 22.34 12.44 13.07
540+ 36.44 27.35 22.63 15.48 ASF-C5 0.98 0.07 0.33 0.02 THFis 0 0 0
0
[0064] From the previous experimental cases, it can be observed how
a process according to the invention allows the lighter and
volatile fractions of the feeding stream 1 to be separated
extremely effectively and markedly from the heavier and solid
fractions, the former extremely concentrated in the streams Q7, the
latter concentrated in the streams Q17. More specifically, in the
streams Q7, the content of asphaltenes ASF-05 and maltenes 540+, is
considerably reduced, and the solid THFi residues are practically
eliminated; the latter are almost completely limited to the solid
streams Q17.
[0065] It can also be observed how, by reducing the pressure P6 in
the separator 6, the percentage of asphaltenes ASF-C5 in the stream
Q17 decreases, and consequently the separation and deasphalting
efficacy of the process.
End of numerical examples
[0066] More generically, regardless of the specific conditions of
the previous numerical examples, a process according to the
invention is particularly suitable for treating blow-down streams
1, residues based on hydrocarbons or other organic residues
containing at least 30% by weight, and up to over 45-50% by weight,
of asphaltenes insoluble in pentane and/or other residues insoluble
in tetrahydrofuran.
[0067] As it is not necessary to resort to mechanical
centrifugations, the process according to the invention can bring
the flows treated to temperatures well over 150.degree. C., making
them more fluid and easier to treat in a continuous process--as for
example in the embodiments previously described--rather than batch,
of the overall plant or some of its components. In general, the
invention allows a more effective flushing to be obtained, and also
to actuate the process in an extremely simple plant, as it is
equipped with only one separator 6, i.e. only one separation
column.
[0068] As, on the other hand, the flows treated do not
substantially exceed 450.degree. C. in temperature and generally do
not undergo excessively severe conditions, on the one hand, the
process according to the invention does not degrade or
substantially damage the more volatile components of the residue to
be treated, increasing the quantity extracted, and on the other
hand, avoids the formation of coke in the same plant, reducing the
necessity of maintenance and increasing its operative life.
[0069] The pressure control in the first separator 6 by means of
the flow of motor fluid 9, in particular through a Venturi tube 8,
is suitable for being inserted in a plant functioning in
continuous.
[0070] The embodiment examples previously described can undergo
various modifications and variations, all included in the
protection scope of the invention. The cooled conveyor belt 18, for
example, can be substituted more generally by other cooled
conveyors or supports. All the details can be substituted by
technically equivalent elements. The materials used, for example,
as also the dimensions, can vary according to technical
requirements. It should be noted that an expression such as "A
comprises B, C, D" also comprises and describes the particular case
in which "A is composed of B, C, D". The examples and lists of
possible variants of the present patent application should be
considered as being non-limiting lists.
* * * * *