FR2550545A1 - METHOD AND APPARATUS FOR SIMULTANEOUSLY DEHYDRATING, DESALINATING AND DEASPHALTING A HYDROCARBON MIXTURE - Google Patents

Abstract

THE MIXTURE OF WATER AND A PRECIPITANT IS ADDED, THE ADDITIONED MIXTURE IS INTRODUCED IN A GRAVIMETRIC SEPARATOR OR IT IS SEPARATED IN THREE SUPERIMPOSED PHASES: A LOWER PHASE CONSTITUTED ESSENTIALLY SALT WATER, AN UPPER PHASE CONSTITUTED FROM THE ESSENTIAL MIXTURE PURIFIED HYDROCARBONS AND FLUXANT, AND AN INTERMEDIATE PHASE ESSENTIALLY CONSISTING OF ASPHALTENS AND WATER, THE THREE PHASES ARE EXTRACTED SEPARATELY, AND THE PRECIPITANT IS SEPARATED FROM THE HYDROCARBON MIXTURE THUS DESHYDRATE ET DESHYDRATE, DESHYDRATE.

Description

Method and apparatus for dehydrating, desalting and

  simultaneously de-asphalt a mixture of hydrocarbons.

  The present invention relates to the treatment of a mixture of hydrocarbons, in particular crude oil from which it is desired to remove all or part of the water, the salts and the asphaltenes. This makes it possible to transport or evacuate the purified hydrocarbons.

in better conditions.

  Until now, dehydration, as well as the desalination of a mixture of hydrocarbons and its deasphalting have always been independently conceived. There are numerous processes allowing, at the same time, the

  dehydration and desalting, as well as deasphalting processes, but these two operations are never coupled.

  Mixtures of unpurified hydrocarbons, and in particular heavy crude oils, have a very high density and viscosity. Therefore, it is necessary to "flux" them, that is to say to add them with light hydrocarbons to be able to dehydrate and desalt them However, even after fluxing, it is often difficult to properly dehydrate these crudes, because the asphaltenes

  that they contain tend to trap water.

  When a light flux is used, there is an additional risk of precipitation of part of the asphaltenes with the formation of a stable and thick inaterface Finally, the crude oil, at its exit from the desalting chain, upstream of the column distillation

  which is normally used to regenerate the fluxing agent, poses transfer problems due to its high viscosity.

  These difficulties are, at least in part, attributable to asphaltenes. The elimination is desirable for dehydration.

  The invention aims to dehydrate, desalt and reduce the asphaltenes content of

  crude hydrocarbons in a single operation with, as favorable consequences, improving the rheological behavior of the mixture of purified hydrocarbons.

  The subject of the invention is a method for simultaneously carrying out, in a single operation, the dehydration, the desalting and the deasphalting of a mixture of hydrocarbons, in particular crudes and residues, characterized in that the mixture of water and a precipitant, in that the added mixture is introduced into a gravimetric separator where it separates into three superimposed phases: a lower phase consisting essentially of salt water, an upper phase consisting essentially of mixture of purified and fluxing hydrocarbons, and an intermediate phase essentially consisting of asphaltenes and water, in that the three phases are extracted separately, and in that the precipitant is separated from the mixture of hydrocarbons thus dehydrated, desalted

and deasphalted.

  3 u As a precipitant, it is generally advantageous to use a light gasoline. Similarly, particularly advantageous results are obtained by adding a demulsifier to the mixture of hydrocarbons.

before treatment.

  For the practice of the process according to the invention, it is generally preferable to carry out the separation of the precipitant by distillation.

  rapid, as well as carrying out the treatment under a pressure higher than atmospheric pressure, in particular under nitrogen pressure.

  Phaltene + a s can be easily recovered by rapid distillation of the intermediate phase extracted from the separator Gravimetric separation is favored by the presence of a high-voltage electric field It is generally possible to carry out all of the treatment according to the method of the invention at a temperature of the order of 90 to 1100 C, which is a temperature significantly lower than that normally used to dehydrate crudes according to conventional methods which require

  temperatures of the order of 130 to 150 C.

  A subject of the invention is also a purifying apparatus for extracting water, salt and asphaltenes from a mixture of hydrocarbons according to the process of the invention. This apparatus is characterized in that it consists essentially of a vertical container comprising a first supply pipe for the mixture to be treated and a second salt water extraction pipe, opening at the base of the container, a third pipe

  extraction of the purified hydrocarbon mixture opening at the top of the container, and a fourth pipe for extraction of a mixture of water and asphaltenes.

  Such an apparatus preferably comprises, between the third and fourth conduits, at least two spaced apart conductive plates each connected respectively to one of the poles of a current source

high voltage electric.

  An apparatus according to the invention advantageously comprises means for heating the mixture under treatment as well as means for placing and maintaining

under pressure.

  For flexible and regular operation, an apparatus according to the invention comprises means for detecting the situation of the layer of water mixture

  and asphaltene from the entrance to the fourth pipeline.

  The invention will be better understood on reading a few detailed examples of implementing the method of the invention, as well as on examining the appended drawing which represents, by way of example, a

  apparatus according to the invention inserted in a crude hydrocarbon treatment installation.

  The installation shown schematically 15 in the drawing essentially comprises a tank 11 containing the mixture of crude hydrocarbons to be treated. A pump 12 conveys this crude mixture by a pipe 13, to a first pipe 2 for supplying the mixture to be treated in a purifying device according to the invention 15 This pipe 13 includes heating means shown diagrammatically by a dotted line which bring the crude mixture kept at approximately C in the tank 11, up to 100 C

  the inlet of the pipe 2 supplying the device 25 according to the invention.

  In 16, a demulsifier is injected into line 13, and in 17, fresh water is injected into this same line. Between lines 16 and 17, light petrol is injected into the same line 13. contained in a tank 18.

  A pump 19 allows the desired quantities of light fuel to be injected into the crude. Valves 20, 21 and 22 allow certain portions to be isolated at will.

of line 13.

  The purifying apparatus 15, according to the invention, is essentially constituted by a vertical insulated container 1 and comprising conventional heating means 8 At the base of the container 1 opens a first supply line for the mixture to be treated 2, as well as 'a second salt water extraction pipe 3 At the top of the container 1 opens a third pipe 4 for extracting the purified hydrocarbon mixture This pipe 4 brings the dehydrated, desalted and deasphalted mixture of hydrocarbons 10 to an apparatus rapid distillation 23 of the so-called "flash" type essentially constituted by a distillation column without tray, operating by expansion and comprising heating means From this distillation apparatus 23, gasoline is extracted at the top, by a pipe 24 slightly recovered from the mixture

  of treated hydrocarbons The light gasoline thus recovered is brought to tank 18, in order to be recycled.

  In the lower part of the distillation apparatus 23 is extracted, by a pipe 25, the mixture of purified hydrocarbons. Inside the purifier apparatus two are arranged two conductive plates 6, 7 separated from one 'other and connected, each, respectively to the poles of a high voltage electric current source, not shown.

  The two plates 6, 7 are arranged approximately at the upper third of the container 1, in the liquid phase consisting essentially of a mixture of purified hydrocarbons and light gasoline serving

fluxing.

  In the lower third of the container 1 there opens a fourth pipe 5 for extracting the mixture of water and asphaltene constituting an intermediate phase between the upper phase of purified hydrocarbons and the lower phase consisting essentially of salt water Conventional detector means o 10 make it possible to control the situa Lion of the layer of water and asphalt mixture which constitutes the interface with respect to the inlet of the fourth pipe 5 These detector means 10 control, by means of relays 26 , the operation or stopping of a pump 27 which sucks, via the line 5, the mixture of asphaltene and water and discharges it into a rapid distillation apparatus 28 of structure similar to that of l distillation apparatus 23 already described from which the asphaltenes are extracted by a lower pipe 29, while the light gasoline partially present in the mixture of asphaltenes and water is extracted at the top of the distillation apparatus 28, through a pipe 30 and, after cooling at 31, either

  recovered, or recycled through a line 32 bringing the light gasoline thus recovered to the tank 18.

  Of course, the pipes 5 and 29 are insulated and include heating means, in order to prevent the asphaltenes from freezing.

  Such an installation can be used for a continuous treatment of crude hydrocarbons. The residence time is approximately 10 minutes in the apparatus, the electric field of the order of 12 k V and it is preferable to maintain a pressure of 7 bar nitrogen

  which is injected into line 4, through line 9, as shown in the diagram.

  Such an installation is used for example with effluents brought to 70 ° C. before mixing, a retention time in the separator 15 minutes, a pressure in this same apparatus of 3 relative bars of nitrogen, a temperature in the still of 110 e C under atmospheric pressure and a temperature of about 150 C in the distiller 35 of a Sphaltenes under very slight overpressure

  and an electric field between the grids 6, 7 of about 1000 volts per centimeter of spacing.

EXAMPLE 1

  As the mixture of crude hydrocarbons to be treated, 5 is used crude oil Mormora mare from Italy, whose density at 15 C is

  1019 kg / m 3 and the viscosity is 100,000 cst at 20 C.

  To 100 volumes of this crude oil, containing 1 volume of water, and at a flow rate of 4 liters / hour, 10 25 volumes of washing water are added with a flow rate of 1 liter / hour, 300 volumes of light gasoline ( 15-80 C) at a flow rate of 12 liters / hour and 0.01 volume of demulsifier of the type sold under the trade name

  of Visco Q 3 E from the company known as Nalco, at a flow rate of 0.016 liters / hour.

  This mixture is injected through line 2

  in the device 15 o it is treated at 110 C.

  Via line 3, 21.2 volumes of salt water are extracted at a flow rate of approximately 0.85 liters / hour. Via line 5, after distillation in the apparatus 28, a mixture of 9.5 volumes of asphaltene is extracted on the one hand at a flow rate of 0.37 liters / hour and 3.5 volumes of water under a flow rate of 0.14 liters / hour, via line 29 Through line 30, 46.3 volumes of light fuel are recovered

at a flow rate of 1.3 liters / hour.

  At the outlet of the distiller 23, 254 volumes of light petrol are recovered via the line 24 at a flow rate of 10.17 liters / hour, mixed with

  0.3 volume of water at a flow rate of 0.012 liters / hour.

  Finally, via line 25, 90 volumes of deasphalted, desalted and dehydrated crude oil are recovered at a flow rate of 3.6 liters / hour, the viscosity of which is

440 cst at 20 C.

EXAMPLE 2

  We use for this example crude oil called Boscan from Venezuela, whose density at 15 C is 998 kg / m 3 Its viscosity at 20 C is 300,000 cst It contains about 11% by weight of asphaltene. To 100 volumes of this crude oil, 25 volumes of washing water and 250 volumes of light gasoline (15-80 C) are added and this mixture, without demulsifier, is injected through line 2, into the treatment apparatus o it is treated for 15 minutes at 900 C. Via line 3, 17.7 volumes of salt water are extracted Via line 30, 45 volumes of light gasoline and 7.2 volumes of water are recovered Via line 29, extracts 25 volumes of raw asphaltene. Via line 24, 205 volumes of light petrol and 0.1 volume of water are recovered, while

  via line 25, 75 volumes of crude deasphalted, desalted and dehydrated hydrocarbons are recovered, the viscosity of which is 725 cst at 20 ° C. and the content of asphaltene is 1% by weight.

  To assess the influence of the treatment temperature in the apparatus 15, the same treatment is carried out as in Example 1 and with the same

  produced, but at 90 C instead of 110 C.

  After treatment, the crude water content, which was 0.8% before treatment, drops to 0.05% after treatment at 90 C and to less than 0.03%

after treatment at 110 C.

  The asphaltene content, initially 12% by weight, drops to 1.2% by treatment at 900 ° C.

  and 0.6% by treatment at 110 C.

  The viscosity at 20 C, which was 100,000 cst for the crude before treatment, drops to 725 cst

  after treatment at 90 C and 440 cst after treatment 35 at 110 C.

  In all the foregoing, reference has been made to fresh water but it is understood that other suitable waters could be used such as sea water, deposit water, etc. 1 O

Claims (17)

  1 Method for simultaneously carrying out, in a single operation, the dehydration, the desalting and the deasphalting of a mixture of hydrocarbons, in particular crude and residues, characterized in that the mixture of water and a precipitating, in that the added mixture is introduced into a gravimetric separator where it separates into three superimposed phases: a lower phase consisting essentially of salt water, an upper phase consisting essentially of the mixture of purified hydrocarbon 1 and fluxing agent , and an intermediate phase essentially consisting of asphaltenes and water, in that the three phases are extracted separately, and   in that the precipitant is separated from the mixture of hydrocarbons thus dehydrated, desalted and deasphalted.   2 Method according to claim 1, characterized in that one uses, as precipitant, a light petrol.   3 Method according to claim 1 or 2,   characterized in that a demulsifier is also added before treatment to the mixture of hydrocarbons.   4 Method according to one of claims   1 to 3, characterized in that the separation of the precipitant is carried out by rapid distillation.   Method according to one of the claims   i to 4, characterized in that the treatment is carried out   under pressure higher than atmospheric pressure.   6 Method according to one of claims 5 1 to 5, characterized in that the asphaltenes are recovered by rapid distillation of the lower phase extracted from the separator.   7 Method according to one of claims   1 to 6, characterized in that the gravimetric separation is carried out under a high voltage electric field.   8 Method according to one of claims   1 to 7, characterized in that the entire treatment is carried out at a temperature of the order of 90 to 110 C.   9 Purifier for removing water, salt and asphaltenes from a mixture of hydrocarbons   according to the method of one of claims 1 to 8, characterized in that it consists essentially of a vertical container (1) comprising a first supply line for the mixture to be treated (2) and a second supply line salt water extraction (3),   opening at the base of the container, a third line for extracting the purified hydrocarbon mixture (4) opening at the top of the container, and a fourth line for extracting a mixture of water and as25 phaltenes (5) opening into the container between the   second and third pipes (3, 4).   Apparatus according to claim 9, characterized in that it comprises, between the third (4) and fourth (5) pipes (4, 5) at least two spaced apart conductive plates (6, 7) each connected respectively to one of the poles 'a source of high voltage electric current.   11 Apparatus according to one of claims   9 and 10, characterized in that it comprises means 35 for heating (8) of the mixture being treated.   12 Apparatus according to one of claims   9 to 11, characterized in that it includes means for pressurizing and maintaining (9).   13 Apparatus according to one of claims   9 to 12, characterized in that it comprises means for detecting (10) the situation of the layer of mixture of water and asphaltene tar relative to the inlet of the fourth pipe (5).