阅读说明：本技术 精炼厂吹扫物流的物理分离方法 (Physical separation of refinery purge streams ) 是由 阿尔贝托·兰多尼 斯特凡尼亚·圭代蒂 朱塞佩·贝尔蒙特 于 2018-03-29 设计创作，主要内容包括：本发明涉及一种精炼厂吹扫物流中存在的转化度高于或等于90％的固体和沥青质的物理分离方法。所述方法提供了将精炼厂吹扫物流加热至高于或等于185℃且不超过220℃的温度,和然后通过以受控的方式将温度逐渐降低至100℃的最低温度,使所述加热的吹扫物沉降,不搅拌所述吹扫物,以形成相对于密度定义的轻相和重相。(The present invention relates to a process for the physical separation of solids and asphaltenes present in a refinery purge stream with a degree of conversion greater than or equal to 90%. The process provides for heating a refinery purge stream to a temperature greater than or equal to 185 ℃ and not more than 220 ℃, and then allowing the heated purge to settle without agitation of the purge by gradually reducing the temperature in a controlled manner to a minimum temperature of 100 ℃ to form a light phase and a heavy phase defined with respect to density.)

1. A process for the physical separation of solids and asphaltenes present in a refinery purge stream having a degree of conversion greater than or equal to 90%, the process comprising the steps of:

-heating the refinery purge stream to a temperature greater than or equal to 185 ℃ and not more than 220 ℃, and, then,

-allowing the heated purge to settle without stirring the purge by gradually reducing the temperature in a controlled manner to a minimum temperature of 100 ℃, thereby forming a light phase and a heavy phase with respect to density.

2. The method of claim 1, wherein the purge stream is from a hydroconversion process in a slurry phase.

3. The method of claim 1 or 2, wherein the heated purge is cooled to a temperature ranging from 100 ℃ to 170 ℃.

4. The method of claim 3, wherein the purge is cooled to a temperature of 100 ℃ to 160 ℃.

5. A method according to any one of claims 1 to 4 wherein the time required to form the dense phase is from 15 minutes to 2 hours.

6. A method according to claim 5, wherein the time required to form the dense phase is from 20 minutes to 1 hour.

7. The method of any one of claims 1-6, wherein the settling velocity ranges from 85 mm/hr to 150 mm/hr.

Technical Field

The present invention relates to a process for the physical separation of asphaltenes and solids such as coke and metals present in refinery purge (purge) streams at a conversion greater than or equal to 90%.

The invention can be applied to the field of refining of heavy crude oil.

The process can be used to treat purge streams from hydroconversion processes in the slurry phase, especially the Eni Slurry Technology (EST).

In the present patent application, the term "refinery purge stream" means a stream comprising hydrocarbons boiling above or equal to 140 ℃ in the slurry phase, said stream being characterized by the presence of an amount of asphaltenes higher than or equal to 5% by weight and by the presence of solids higher than or equal to 5% by weight.

for the purposes of the present invention, the term "solid" refers to a fraction insoluble in tetrahydrofuran, which is referred to herein by the abbreviation THF-i.

For the purposes of the present invention, the term "asphaltenes" refers to moieties that are soluble in tetrahydrofuran but insoluble in n-pentane.

Asphaltenes are based on normal alkanes (usually having 5 to 7 carbon atoms C)₅-C₇) Insolubility in (b) was classified. These compounds generally consist of a condensed aromatic core variously branched and linked to each other by sulfur bridges or by linear chains. These compounds have a heteroatom (S, N) concentrated within them, which imparts polarity to them. By subjecting the asphaltene-rich stream to hydroconversion, it can be observed how they change their own structure after hydrogenolysis of the sulphur bridge and cracking of the alkyl side chains, and in fact they become smaller (molecular weight reduction). The decrease in size results in an increase in its polar and aromatic nature. The higher the degree of condensation, the less soluble they become. The increase in polarity and aromaticity results in their greater tendency to peptize, which consequently tends to aggregate and precipitate.

In this case, the increase in temperature increases the entropy of the system and prevents aggregation. This is why the higher the degree of conversion of the asphaltenes, the higher the temperature at which they must be dispersed in the hydrocarbon matrix.

In this patent application, all operating conditions indicated herein should be considered as preferred conditions, even if not explicitly stated.

For the purposes of the present invention, the terms "comprising" or "including" also include the terms "consisting of … …" or "consisting essentially of … …".

For the purposes of the present invention, the definition of a range always includes the endpoints (extrames), unless otherwise specified.

Background

Patent application WO 2014/025561 describes a process for recovering catalyst by hydrocracking the effluent from a slurry hydrocracking zone. The process provides for separating the effluent into a first stream comprising solvent and clarified product (pitch) and a second stream comprising pitch and catalyst.

The separation may be performed by centrifugation, filtration, decantation or electrostatic separation. The second stream is treated by acid leaching to extract the catalyst and form an aqueous solution and a residue. The aqueous solution is then treated with anions to form insoluble salts, a catalyst, and an additional aqueous solution.

US 2013/0247406 describes a process that integrates the upgrading process of heavy crude oil to convert it into lighter products in the presence of a catalyst; a method of oil removal wherein heavy residues and heavier products from processing heavy crude oil are separated from the spent catalyst which is subsequently recovered; and a catalyst synthesis zone.

The separation of the catalyst is carried out by a membrane filtration technique treatment followed by a thermal devolatilization step.

US 8,470,251 describes a process for treating crude oil by hydroconversion, wherein a slurry stream from hydrocracking is treated in a first distillation column under vacuum forming three fractions, wherein the first residue has a boiling point above 450 ℃ (pitch). This residue is then treated in a second distillation column under Vacuum to remove a content of up to 14 wt% of Heavy Gas Oil under reduced pressure (HVGO), thereby forming a second residue (pitch) that is sent for pelletization.

WO 2009/070778 describes a process for recovering metals from spent catalysts used in slurry processes for heavy oil upgrading. According to WO 2009/070778, the phase containing the spent catalyst is pyrolyzed and the pyrolysis residue is contacted with a leaching solution containing ammonia and air to dissolve the metals of groups VIB and VIII and form a pressurized slurry. The slurry contains at least one soluble group VIB and VIII metal complex, ammonium sulfate and a solid residue containing at least one group VB metal complex and coke.

The residual solids from the pressurized slurry containing ammonium metavanadate and coke are then separated and removed. A portion of the group VIII metal precipitates. The precipitation is carried out at a predetermined pH to selectively precipitate a portion of the group VIB and group VIII metal complexes.

US 2010/0122938 relates to a process for separating an ultra-fine hydrocracking solid catalyst present in an amount of 5 to 40 wt% from a liquid slurry of hydrocarbons. The slurry is cooled to a temperature of 55 ℃ to 75 ℃ and mixed with a solvent at a solvent to slurry weight ratio of 3:1 to 1:3 to form a first mixture comprising liquid hydrocarbons, solvent, and a stream comprising heavy hydrocarbons encapsulating the solids of the catalyst. The first mixture is centrifuged to form a second mixture of low concentration of heavy hydrocarbons containing solids encapsulating the catalyst and a third mixture of heavy hydrocarbons containing solids encapsulating the catalyst. The second mixture is centrifuged to form a fourth mixture containing solvent and liquid hydrocarbons, and a fifth mixture containing a substantial concentration of heavy hydrocarbons encapsulating the solids of the catalyst. The mixtures are then combined and dried to form a mixture of hydrocarbons, which contain some impurities in the gas phase, and solid coke-type residue. These impurities are separated from the hydrocarbons and recovered as a solid residue.

US 7,790,646 describes a process for converting a fine catalyst, present at a level of from 5 to 40 wt%, and included with heavy oil in a slurry stream, to a coke-type material, and then recovering the metals of the catalyst therefrom. The method comprises the following steps. The slurry containing heavy oil and spent catalyst, which contains sulfides of group VIII and VI metals, is mixed with a solvent, preferably at a temperature of 25 ℃ to 80 ℃, preferably in a volume ratio of 0.5/1 to 5/1, to cause precipitation of asphaltenes.

The spent catalyst and asphaltenes are preferably separated by decantation and/or centrifugation to precipitate the heavy oil and separate them from the solvent. The precipitated asphaltenes are converted into coke-type material containing metals that can be recovered by pyrolysis.

EP 2440635 describes a process for recovering metals from a stream rich in hydrocarbon and carbon residues. The stream is sent to a primary treatment, which is carried out in one or more steps, in the presence of fluxes, at a temperature of 80 ℃ to 180 ℃, in a suitable plant, and subjected to liquid/solid separation to obtain a clarified product consisting of a liquid and a cake. The cake is optionally dried to remove hydrocarbon components from the cake that have boiling points below a temperature of 300 ℃ to 350 ℃. Sending the optionally dried cake to a secondary heat treatment comprising flameless pyrolysis at a temperature of 400 ℃ to 800 ℃; the oxidation of the pyrolysis residue is subsequently carried out under oxidation conditions and at a temperature of from 400 ℃ to 800 ℃.

Disclosure of Invention

It is an object of the present invention to separate asphaltenes that accumulate and settle with the solids present from refinery purge streams.

Accordingly, an object of the present invention is directed to a process for the physical separation of asphaltenes and solids present in a refinery purge stream at a conversion of greater than or equal to 90%. The method comprises the following steps:

-heating the refinery purge stream to a temperature greater than or equal to 185 ℃ and not more than 220 ℃, and, then,

-subjecting the heated purge to static settling by gradually reducing the temperature in a controlled manner to a minimum temperature of 100 ℃, thereby forming a light phase and a heavy phase defined with respect to their density.

during the controlled temperature reduction, purge stratification by formation of two phases, characterized by different densities and viscosities, was observed. The denser or heavier phase is called the "cake", while the sparser or lighter phase is referred to as the "clarified product". The heavy phase is naturally always the lower partial layer below the light phase.

The purge produced in a refinery has the following characteristics. Metals and solids (not soluble in THF) can be present in high concentrations. Asphaltenes can be present at high concentrations at greater than or equal to 90% conversion.

the high viscosity and low stability of the purge make it necessary to operate at high temperatures (greater than or equal to 220 ℃) in order to be mobile and available to the user (asphalt for cement plants, gasification). The above noted characteristics make the purge a product that is much less valuable than fuel oil or fuel for marine transport (commercially known as ATZ fuel).

Although the purge contains metal, its concentration is insufficient to make it economically sustainable for metal recovery. The purge is typically used as a liquid fuel for cement plants, or gasification with a low percentage of feed.

Both of these uses result in yield losses for the hydroconversion process that are equivalent to the percentage of purge used, typically 5 to 10 wt% calculated relative to the feed.

On the other hand, the process object of the present patent application allows to exploit the low stability of the purge, since this feature promotes the physical separation by a controlled reduction of the temperature, resulting in a separation of the two phases: cake and clear product.

In the present patent application, the term "clarified product" refers to a hydrocarbon residue free of solids and metals, in which the content of asphaltenes is lower than that originally present in the purge and which is already fluid in the temperature range of 100 ℃ to 160 ℃.

In the present patent application, the term "cake" refers to a solid having characteristics of being easily ground at room temperature and therefore being transportable even over long distances without any particular thermostatic regulation. This feature is maintained at a temperature varying in the range of 50 ℃ to 60 ℃.

The process, object of the present patent application provides the advantage of concentrating metals and solids in the cake.

The resulting cake can be used as a solid fuel for boilers, cement plants and steel plants, or can also be sent to processing for metal recovery.

the process, object of the present patent application also provides the advantage of recycling the clarified products in the feed to the hydroconversion process, thus maximizing the conversion itself. The clarified product may also be used in admixture as ATZ fuel or gasification charge.

In short, the method, object of the present patent application allows upgrading of purge from a refinery process.

The invention also allows the use of relatively mild operating conditions in terms of temperatures not exceeding 220 ℃ and pressures below 6 bar. Thus, the method described and claimed is performed in a simple device comprising a sinker and cochlea (cochlea).

Other objects and advantages of the present invention will become more apparent from the following description and drawings, which are provided for illustrative and non-limiting purposes only and represent preferred embodiments of the present invention.

Drawings

Figure 1 shows a preferred embodiment of the present invention. In the block diagram, (a) and (D) are heat exchange devices, (B) is a settler, (C) is a cochlea, (M) is a motor, (1) is a refinery purge stream, (2) is a heated purge stream, (3) is a clarified stream, and (4) is a separated dense/solid phase.

FIG. 2 shows the behavior of a refinery purge after cooling; an abnormal trend of the viscosity curve with respect to temperature was observed below a certain temperature.

Detailed Description

The method, object of the present patent application will now be described in detail with particular reference to fig. 1.

The object of the present invention relates to a process for the physical separation of solids and asphaltenes present in a refinery purge stream with a conversion greater than or equal to 90%. The method comprises the following steps:

-heating a refinery purge stream at a temperature greater than or equal to 185 ℃ and not more than 220 ℃, and, then,

-allowing the heated purge to settle, without stirring the purge, by gradually reducing the temperature in a controlled manner to a minimum temperature of 100 ℃, thereby forming a light phase and a heavy phase with respect to their density.

In fig. 1, a preferred application of the method according to the invention is depicted. The refinery purge stream (1) is heated in heat exchange unit (a) at a temperature greater than or equal to 185 ℃ and not more than 220 ℃, preferably in the temperature range of 190 ℃ to 200 ℃. The heated purge (2) proved to be homogeneous; the purge is considered uniform when a volume V sample is defined, the composition and rheological properties of which remain unchanged regardless of which part of the sample is considered.

Once the purge (2) has been heated, it is introduced into the settler (B), the bottom (E) of which is preferably heated by means of heat exchange means (D). The settling is achieved by a gradual and controlled reduction of the temperature, bringing the purge temperature to a temperature varying in the range of 100 ℃ to 170 ℃, preferably in the range of 100 ℃ to 160 ℃, more preferably in the range of 120 ℃ to 150 ℃.

The temperature must render the asphaltenes insoluble and at the same time make the clarified fraction mobile, allowing its extraction.

The separation of the dense phase is optimal in the temperature range of 120 ℃ to 150 ℃.

The time required for forming the heavy phase may be 15 minutes to 2 hours, preferably 20 minutes to 1 hour, more preferably 30 minutes to 45 minutes. The settling rate may vary depending on the composition of the purge and in any case ranges from 85 mm/hour to 150 mm/hour.

This rate was measured experimentally by monitoring the displacement of the interface between the cake and the clarified product with respect to time.

Using a cylindrical container, it was filled with a purge and placed in an oven at a temperature T220 ℃, and once completely melted, the temperature of the oven was reduced to 150 ℃.

after a preset time (t), the cylinder is removed from the oven, the "clear" phase is poured off, and once cooled, the height of the remaining dense phase is measured.

With a controlled decrease in temperature, a heavy, dense phase (4) is formed, which is denoted herein as a "cake". Once the cake has settled and consolidated, it can be separated by the cochlea (C) at the bottom. The cake was then cooled to room temperature.

During the separation, a light or clear phase (3) is also formed, which is collected by a dip tube located in the upper part of the settler (not shown in fig. 1). The operating temperature of the settler must destabilize the purge while allowing the clarified phase to move. Temperatures below 100 c may prevent the displacement of the clear phase.

The physical separation of the refinery purge takes advantage of the temperature effect, the controlled reduction to the temperatures indicated herein results in the deposition of the most insoluble asphaltene compounds, which aggregate and settle with the solids and heavy metals.

The clarified product is preferably recycled upstream of the possible process.

The resulting cake is hard at room temperature, has a softening point of 80 ℃ to 100 ℃ and a degree of penetration of 2 to 5dmm (dmm means ten mm).

The softening point is the temperature at which the solid cake softens, which indicates the temperature dependence of the consistency of the cake. The degree of penetration was measured at room temperature using a needle of known weight according to the method of ASTM-D5-06, and the degree of penetration of the material was expressed in units of ten millimeters.

The consistency of the separated cake is due to the high concentration of asphaltene compounds and the reduction of the content of maltenes relative to the starting product. In contrast, the clarified product is rich in maltenes and the asphaltene content is significantly reduced.

In order to better understand the scope of the invention and the applications, some examples are provided below, even though they in no way represent a limitation of the scope of the invention.