RU2504575C2 - Method and apparatus for separating coal tar from suspended-phase hydrocracked vacuum gas oil and composition thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of converting heavy hydrocarbon material to lighter hydrocarbon products and separating coal tar, which involves hydrocracking the heavy hydrocarbon material suspended with a granular solid material in the presence of hydrogen in a hydrocracking reactor to form a hydrocracked stream containing vacuum gas oil and coal tar. Gas oil is separated from coal tar in a first vacuum column and further separation of vacuum gas oil from coal tar is carried out in a second vacuum column. The invention also relates to apparatus for converting heavy hydrocarbon material to lighter hydrocarbon products and separating coal tar.

EFFECT: obtaining coal tar from which particles capable of being transformed without sticking can be prepared.

10 cl, 2 dwg, 1 tbl, 1 ex

Description

BACKGROUND OF THE INVENTION

The present invention relates to a method and apparatus for processing crude oils and, more specifically, to the hydroconversion of heavy hydrocarbons in the presence of additives and catalysts, resulting in useful products, followed by the preparation of raw materials for conversion plants of refineries, such as FCC (catalytic cracking units) in the fluidized bed) or hydrocracking.

Hydroconversion methods designed to convert heavy hydrocarbon oils into high-quality light and intermediate ligroins and for reforming various kinds of raw materials, boiler fuel and gas oil are well known. These heavy hydrocarbon oils may include materials such as crude oil itself, atmospheric distillation residual products, vacuum distillation residual products, heavy recycle gas oils, shale oils, coal liquids, crude oil residues, topped oil and heavy tar oils derived from oil sands . Of particular interest are oils derived from oil sands and which contain materials with wide boiling ranges from naphtha to kerosene, gas oil, pitch, etc., of which a large proportion of the material boils above 538 ° C (100 ° F).

As stocks of traditional crude oils become depleted, these heavy oils must be refined to meet current needs. In this refinement, heavier materials turn into lighter fractions and in this case most of the sulfur, nitrogen and metals should be removed. Crude oil is typically first processed in an atmospheric distillation column to form fuel products that include naphtha, kerosene and diesel. The bottom stream of an atmospheric oil distillation column is typically sent to a vacuum distillation column to produce vacuum gas oil (SH), which can serve as a feedstock for the FCC unit or for other applications. VG usually boils between 300 ° C (572 ° F) and 538 ° C (1000 ° F). The bottom residue of the vacuum column usually contains at least 9 wt.% Hydrogen at a density below 1.05 g / cm ³ on an ash-free basis (without inorganic matter). The bottom residue of a vacuum column is usually processed at a primary refining unit, after which it is sent to an oil refinery for processing into useful products. Initial refinement plants known in the art include, but are not limited to, coking processes, such as delayed coking or fluidized bed coking, and hydrogen addition processes, such as fluidized bed hydrocracking or slurry phase (GSF). All of these primary enrichment technologies, such as delayed coking, fluidized bed hydrocracking and slurry hydrocracking, contribute to the conversion of vacuum residues of crude oil into HB with boiling ranges from 343 to 538 ° C (650 to 1000 ° F) in terms of atmospheric conditions .

At a preferred conversion level of 80-95% by weight of materials boiling above 524 ° C (975 ° F) turning into a material boiling at 52 ° C or lower, GSF produces a pitch by-product with a yield of 5-20 weight. % calculated on an ashless basis. By definition, pitch is a hydrocarbon material boiling above 538 ° C (1000 ° F) in terms of atmospheric pressure, as determined by some standard distillation modeling gas chromatographic method such as ASTM D2887, D6352 or D7169 disclosed, all of which used in the oil industry. These definitions of “conversion” and “pitch” narrow the range of converted products related to pitch conversion. The pitch by-product is solid at room temperature and is characterized by minimum pumping temperatures above 250 ° C, which makes it almost impossible to move it any long distance, since the pipeline would have to be equipped with a jacket heated by hot oil or electricity. The pitch also contains inorganic solid material that can settle. Thus, in order to prevent subsidence, it is necessary to mix or circulate in the storage tank, which requires additional capital and operating costs.

When heated to the softening area, adhesion between solid materials will occur. The occurrence of adhesion or the presence of a softening point is difficult to determine and this may require long-term empirical tests, for example, by adhesion of solid materials under the design load in a kind of silo with subsequent measurement of the shear force required to move the solid materials. Such standard tests include ASTM D6773 using the Schulz ring shear tester and ASTM D6128 using the Enike ring shear tester. Peck is not a pure compound and melts over a wide range. For this reason, differential scanning calorimetry (DSC) will not be able to establish a specific melting peak, which could be used for quick instrumental analysis.

The pitch softening point is traditionally measured by determining the softening point by the ring and ball method, ASTM D36, or by determining the softening point by the Mettler method, ASTM D3104. Both of these methods are suitable for determining the temperature at which a material begins to flow like a liquid. This point can, in particular, be used to establish the minimum temperature for the pitch in the form of a liquid in the preparation of asphalt binder for paving, roofing and other industrial applications. However, this information does not say anything about the onset of softening and cannot be directly used to determine at what point the solid material should undergo plastic deformation or begin to stick together.

Hardening of the pitch can be accompanied by the formation of dust, since pitch with a higher softening point can become brittle. However, pitch with a lower softening point may become sticky, making it difficult to work with it in bulk.

To obtain an easier-to-handle pitch, more sophisticated methods for processing the pitch obtained from GSF are needed. In addition, more sophisticated methods are needed to evaluate how easy it is to work with the pitch.

Disclosure of invention

Applicant has found that using a second vacuum column to isolate products from the GSF reactor produces a less sticky pitch that is easier to cure. The second vacuum column, in addition, separates from the SHG pitch, which can be returned to the hydrocracking reactor in the suspension phase. Part of the pitch from the first vacuum column can be returned to the hydrocracking reactor in suspension phase. The use of a second vacuum column reduces the temperature in both vacuum columns, thereby reducing coke formation and cracking problems. The pitch by-product can then be molded into solid particles, which are a free-flowing solid mass that is easy to handle at predetermined conveying temperatures. The use of two vacuum columns can also reduce the temperature of the pitch, and thereby avoid coking of heating devices. Pitch with a VG content below 14 wt.% In solid form does not become sticky when exposed to the expected transport temperatures.

Brief Description of the Drawings

For a better understanding of the invention should refer to the accompanying drawings:

figure 1 is a schematic representation of a technological diagram showing the method and installation of the present invention;

FIG. 2 is a schematic diagram of a flow diagram showing an alternative method and installation of the present invention.

The implementation of the invention

The method and apparatus of the present invention are capable of converting a wide range of heavy hydrocarbon feedstocks into lighter hydrocarbon products. They allow the processing of aromatic raw materials, as well as raw materials that are traditionally very difficult to hydroprocess, for example vacuum distillation bottoms, partially distilled vacuum distillation residues, deasphalted distillation materials, unspecified asphalt, bottom sediment from storage tanks, etc. Suitable raw materials include atmospheric distillation residue boiling at 343 ° C (650 ° F) or higher, heavy VH and vacuum distillation residue boiling at 426 ° C (800 ° F) or higher, and a vacuum distillation residue boiling above 510 ° C (950 ° F). The boiling points given in this description assume boiling points in terms of atmospheric pressure, based on the observed boiling point and distillation pressure using the equations proposed in ASTM D1160 appendix A7 called Practice for Converting Observed Vapor Temperatures to Atmospheric Equivalent Temperatures (Manual by recalculating the observed vapor temperatures to temperatures for atmospheric pressure). The term "pitch" refers to the remainder of the vacuum distillation or to a material with a boiling point, calculated for atmospheric pressure, above 538 ° C (1000 ° F).

The installation includes a suspension phase hydrocracking reactor 20, a first vacuum column 90, and a second vacuum column 100. In the fractionation column 50, a suspension hydrocracked product for the first vacuum column 100 can be prepared, and the granulation machine 130 can solidify the pitch to solid particles.

In the GSF process shown in FIG. 1, the coking inhibitor or catalyst of particulate material in line 6 is mixed with a heavy hydrocarbon recycle, such as recycled heavy HB, and / or pitch in line 8 to the feed tank 10, resulting in a well mixed homogeneous suspension. In one aspect, various solid catalyst particles can be used as the granular material, provided that these solid particles can withstand the hydrocracking process and remain effective as part of the recycle. Particularly valuable catalyst particles are those described in US Pat. No. 4,963,247. Typically, these particles are iron (II) sulfate particles smaller than 45 microns, the main part of which, i.e. the component, in one aspect, at least 50 wt.%, has a particle size of less than 10 microns. A preferred catalyst is iron (II) sulfate monohydrate. A bauxite catalyst may also be preferred. In one aspect, coking inhibitory catalyst particles are added to the feed mixture in amounts of 0.01 to 4.0% by weight, based on fresh feed. Alternatively or additionally, oil soluble coking inhibitors may be used. Oil soluble additives may be metal naphthenate or metal octanoate in the range from 50 to 1000 weight. ppm based on fresh raw materials in which the metal may be molybdenum, tungsten, ruthenium, nickel, cobalt or iron.

The slurry from the feed tank 10 and the heavy hydrocarbon feed in line 12 are pumped through line 16 to the flame heater 14. The combined feed is heated in heater 14 and pumped through feed line 18 to the inlet of the bottom of the tubular GSF reactor 20. The heater 14 has fresh catalyst particles based on iron, added through line 6, as a rule, are thermally decomposed to smaller iron (II) sulfate with catalytic activity. Partial decomposition will occur in the GSF reactor 20. For example, iron (II) sulfate monohydrate will be converted to iron (II) sulfate with a particle size of less than 0.1 μm or even 0.01 μm at the outlet of the heater 14. GSF reactor 20 it can take the form of a three-phase (solid material - liquid - gas) reactor without a fixed solid layer through which the catalyst, hydrogen and oil feedstock are generally moved upward with some degree of return mixing.

Many layout options for mixing and pumping may be suitable. For example, the feed in line 12 can be mixed with the catalyst from line 6 in the tank 10 instead of or along with the heavy oil recycle from line 8. It is also allowed that the feed streams 8 and 12 can not be mixed together, but added to the GSF reactor 20 separately.

The recycle hydrogen and make-up hydrogen from line 22 is sent to the GSF reactor 20 via line 24 after heating in the heater 26. Hydrogen through line 24 can be introduced at a point above the feed position of the feed through line 18. Both the feed from line 18 and hydrogen from line 24 can be distributed in the GSF reactor 20 using a suitable distributor. In addition, hydrogen from line 23 can be added to the feed in line 16 before the feed is heated in heater 14 and sent to the GSF reactor via line 18, as shown in the diagram. It is also envisaged that a single heater 14 could potentially be used to heat the gas, feed and catalyst stream to form a feed stream in line 18, as a result of which the heater 26 and line 24 may not be involved.

During the course of the GSF reaction, it is important to minimize the formation of coke or some other material, which tends to cause the liquid, solid or semi-solid phases to settle from the bulk of the material in the reactor. This can lead to contamination of the reactor or equipment located after it. The addition of a relatively polar aromatic oil to the feed is one way of minimizing the deposition of coke and other materials. Severe VG is a polar aromatic oil. In one aspect, the heavy SH in line 8 replenishes the feed to the GSF reactor 20 in the range of 0 to 50% by weight, depending on the quality of the feed and the conversion level in a single pass. The feed to the GSF reactor contains three phases: a solid catalyst, liquid hydrocarbons, hydrogen gas, and vaporized hydrocarbons.

The method of the present invention can be carried out, in one aspect, at a completely moderate pressure in the range from 3.5 to 24 MPa without coke formation in the GSF reactor 20. The temperature of the reactor, as a rule, lies in the range from 350 to 600 ° C with a preferred range from 400 to 500 ° C. The hourly space velocity of the liquid is generally below 4 h ^-1 for fresh raw materials, and a range of 0.1 to 3 h ^{-1 is} preferred, and a range of 0.2 to 1 h ^{-1 is} particularly preferred. The conversion of the pitch in one pass can be from 50 to 95 wt.%. The hydrogen feed rate is from 674 to 3370 nm ³ / m ^{3 of} oil product. Although GSF can be carried out in various kinds of known reactors with upward or downward flow, it is particularly suitable for a tubular reactor through which raw materials and gas move up. Therefore, the output from the GSF reactor 20 is above the input. Although only one reactor is shown in FIG. 1, one or more parallel or sequentially located GSF reactors 20 may be used. In one aspect, an anti-foaming agent may also be added to the GSF reactor 20 through its top to reduce the tendency to foam . Suitable anti-foaming agents may be silicones, as disclosed in US Pat. No. 4,969,988. In addition, cold hydrogen may be introduced upstream of the reactor via line 27 to cool the hydrocracking product in suspension phase. It is also conceivable that the cooling line may also, alternatively, contain high-temperature gas, diesel fuel or some other hydrocarbon stream.

The hydrocracked stream containing the gas-liquid mixture is discharged from the top of the GSF reactor 20 along line 28. Hydrocracking in the suspension phase leads to the removal of aliphatic groups from the aromatic rings, but leaves the aromatic rings formed as a hydrocracking product in the suspension phase with a concentration of hydrogen in them 8 wt.% Or lower, mainly 6 wt.% Or lower and, as a rule, at least 4 wt.% On an ash-free basis (without inorganic matter). The hydrocracking product in the suspension phase may also have a density of at least 1.1 g / cm ³ , preferably at least 1.15 g / cm ³ and, as a rule, not higher than 1.3 g / cm ³ on an ash-free basis (without inorganics). The hydrocracking product in the suspension phase also contains from 1 to 10 wt.% Toluene insoluble organic residue. This residue is a non-catalytic solid in the portion of the slurry hydrocracking product boiling above 524 ° C (975 ° F).

The hydrocracked stream from the top of the GSF reactor 20 is a vapor-liquid mixture consisting of several products, including SH and pitch, which can be separated using a number of different methods. The hydrocracked effluent from the top of the GSF reactor 20 is, in one aspect, separated in a hot high pressure separator 30, maintained at a separation temperature of 200 to 470 ° C (392 to 878 ° F) and, in one aspect, at a pressure GSF reactions. A possible cooling agent in line 27 may be an auxiliary means for cooling the reaction products to a predetermined temperature in the hot high-pressure separator 30. In the hot high-pressure separator 30, the effluent from the GSF reactor 20 is separated into a gaseous stream 32 and a liquid stream 34 through line 28. The gaseous stream is a product of single evaporation at temperature and pressure of the hot high-pressure separator 30 and contains from 35 to 80 vol. %, preferably from 50 to 70 vol.% of the hydrocarbon product from the GSF reactor 20. Similarly, the liquid product is a flash liquid phase at the temperature and pressure of the hot high-pressure separator 30. The gas stream is discharged from the top of the hot high pressure separator 30 through line 32, and the liquid phase is discharged from the bottom of the hot high pressure separator 30 through line 34.

The liquid fraction in line 34 is fed into a hot flash drum 36 at the same temperature as the temperature within the hot separator 30 the high pressure but at a pressure of from 690 to 3447 kPa (100 to 500 lb / ^in2). The vapor head fraction in line 38 is cooled in the refrigerator 39 and connected to line 42, which contains the liquid bottom product from the cold high-pressure separator, passing to line 52. The liquid fraction exits the hot evaporation drum through line 40.

The overhead stream from the hot high pressure separator 30 in line 32 is cooled to a lower temperature in one or more of the coolers represented by cooler 44. Water flushing (not shown) on line 32 is typically used to wash off salts such as ammonium bisulfide or ammonium chloride. It is believed that washing with water removes almost all ammonia and some hydrogen sulfide from stream 32. Stream 32 is transferred to a high pressure cold separator 46. In one aspect, the cold high pressure separator is operated at a lower temperature than the hot high pressure separator 30, but at the same pressure. The high pressure cold separator 46 is held at a separation temperature of from 10 to 93 ° C (50 to 200 ° F) and, in one aspect, at the pressure of the GSF reaction. In the cold high-pressure separator 46, the overhead stream from the hot high-pressure separator 30 is separated into a gaseous stream 48 and a liquid stream 42. The gaseous stream is a flash vapor fraction at the temperature and pressure of the high-pressure cold separator 46. Similarly, the liquid product is a flash liquid product at the temperature and pressure of the high pressure cold separator 46 and contains from 20 to 65 vol.%, Mainly from 30 to 50 vol.% Of the hydrocarbon product from the GSF reactor 20. When using this type The separator obtained at the outlet of the gaseous stream contains mainly hydrogen with a certain amount of impurities, such as hydrogen sulfide, ammonia and light hydrocarbon gases.

The hydrogen-rich stream in line 48 can be passed through a packed wash column 54, where it is flushed with a wash liquid from line 56, whereby hydrogen sulfide and ammonia are removed. The spent flushing fluid in line 58, typically an amine, can be regenerated and recycled. The washed hydrogen-rich stream exits the scrubber via line 60 and combines with fresh make-up hydrogen added through line 62 and recycled through the recycle gas compressor 64 and line 22 back to the GSF reactor 20. The make-up hydrogen can be added before or after compressor 64. but in the case of using a cooling agent, the make-up line 62 should be located after the cooling agent line 27.

The liquid fraction in line 42 transfers the liquid product, attaching it to the cooled top product of the hot evaporation drum in line 38, which leaves cooler 39, passing to line 52, which feeds the cold evaporation drum 66 at the same temperature as in the cold separator 46 high pressure, and at a lower pressure from 690 to 3447 kPa (100 to 500 lb / ⁱⁿ²⁾ than in the hot flash drum 36. The effluent from the top of the gas in line 68 may be a fuel gas containing C4-material, which may be allocated and disposed of. The liquid bottom products in line 70 and line 40 for the bottom product from the hot evaporation drum 36 are sent to fractionation section 50.

The fractionation section is located after the GSF reactor 20 and is associated with it. “Located after and connected” means that at least part of the material flowing to the component located after and associated with it can flow from the component with which it communicates in the operating mode. “Bound” means that the flow of material is permitted in an operating mode between numbered components. “Positioned before and bound” means that at least a portion of the material flowing from the component located before can, in operating mode, flow to the component with which it communicates. Section 50 fractionation may contain several devices, although in figure 1 it is presented only in the form of a single device. The fractionation section 50 may include a stripping section and an atmospheric column, but in one aspect there is only one column. To drive lighter components from heavier components, an inert gas, such as medium pressure steam, may be supplied near the bottom of the fractionation section 50 through line 72. The fractionation section 50 produces an overhead gas product in line 74, a naphtha product stream in side product line 76, a diesel fuel product stream in side product line 78, a possible atmospheric gas oil stream in side product line 80, and SH and pitch stream in bottoms product line 82.

A line 82 introduces a portion of the hydrocracked effluent in the bottoms stream from the fractionation section 50 to the flame heater 84 and feeds the heated bottoms stream into the first vacuum column 90, in which a pressure of 1 to 10 kPa (7 to 75 Torr) is maintained, preferably 1 up to 7 kPa (10 to 53 Torr), and at a temperature of vacuum distillation when converted to atmospheric pressure for the fraction between light vacuum gas oil and heavy vacuum gas oil from 371 to 482 ° C (700-900 ° F), mainly from 398 to 454 ° C (750-850 ° F) and most preferably 413 to 441 ° C (775-825 ° F). The first vacuum column is located after the fractionation section 50 and the GSF reactor 20 and is associated with them. The first vacuum column, in one aspect, is a distillation column with a three-stage mixing ejector at the top, which creates a vacuum in the column. At each stage of the ejector, a gas stream is supplied, for example water vapor, which creates a vacuum in front of the ejector in a vacuum column. After each stage of the ejector, the pressure is increased, which causes the head stream to condense in a collector for liquid products that can be taken. Light gases from the third stage of the ejector can be collected and, in one aspect, used as fuel for the flame heater 84. Other types of vacuum equipment may also be suitable. In one aspect, steam can be used in the first vacuum column. Water vapor is supplied via line 99 to the first vacuum column 90 from the steam collector 104.

Three fractions can be distinguished in the first vacuum column: the top fraction of diesel and light hydrocarbons in the upper line 92, the flow of light HB, boiling no higher than 482 ° C (90 ° F) and, as a rule, higher than 300 ° C (572 ° F) ), from a side stream in line 94, a stream of heavy VG boiling above 371 ° C (700 ° F), in line 96 of a side stream and a pitch stream obtained in line 98 for a still product that boils above 450 ° C (842 °) F). Most of the heavy VH in line 96, as a rule, is returned in the form of recycle to the GSF reactor 20. The non-recycle part of the heavy VH is usually obtained as a product for additional conversion in other refinery operations. In order to minimize steam generation, which requires more energy to create a vacuum, part of the light SHG stream in line 94 is cooled by heat transfer and pumped back into the column through line 95, thereby condensing as much condensed material as possible. Another side stream, the paraffin wax in line 97, taken below the side line 96 for the heavy HB and above the bottoms product line 98, which carries the first pitch stream, can be recycled to the GSF reactor 20, which is located after the side stream line 97 for paraffin gacha and is associated with it. In this case, most or all of the stream 96 could be selected as a product heavy VH. When taking the side stream through line 97, less raw material is sent to the second vacuum column 100, which requires a smaller capacity of the column and at the same time improves the quality of the heavy SH in line 96. The paraffin wax stream in line 97 usually has a boiling point below 621 ° C. (1150 ° F) and, preferably, below 607 ° C (1125 ° F). GH flows can also be recycled to earlier stages in order to enhance separation operations.

The first pitch stream in line 98 is supplied to the second vacuum column 100 through line 98, which is located in front of the first vacuum column 90, fractionation column 50 and the GSF reactor 20. The first pitch stream in line 98 is not suitable for mass flow in the form of granular solid material. It is not thermally stable and begins to undergo cracking at temperatures no higher than 300 ° C, if it is exposed to these temperatures for a sufficiently long time. The pitch in line 98 may contain inorganic solids in the range of up to 6-10 wt.%. The high solids content may cause the flame heater 84 to become contaminated by coke formation. The temperature, which is necessary for the vacuum residue, can be reduced by adding water vapor in order to reduce the partial pressure of hydrocarbons or to further reduce the vacuum pressure, which in both cases makes the process more expensive. The temperature of the vacuum residue must be high in order to drive away a sufficient amount of heavy HB from the pitch. The Applicant has determined that hardening of a pitch containing 14% by weight of heavy VH results in sticky particles that are difficult to work with in bulk. The output of the flame heater 84 at a temperature of 385 ° C (725 ° F) allows the first vacuum column 90 to produce a pitch containing not more than 10 wt.% Heavy HH, but the heater 84 undergoes excessive coking.

In the present invention, a second vacuum distillation column 100 is used to further distill the heavy HB from the pitch. In one aspect, the second vacuum distillation column operates at a lower pressure than the pressure in the first vacuum column in order to achieve the distillation of the SH, necessary to obtain a pitch that can be formed into particles suitable for working with them in bulk. The use of the second vacuum column 100 provides a lower temperature in the flame heater 84 located in front of the first vacuum column 90 at 377 ° C (710 ° F) or lower, and, in one aspect, at 370 ° C (698 ° F) or lower, thereby reducing the likelihood of pollution due to coke formation. When stripping is carried out in the first vacuum column 90, the first pitch stream in line 98 may be supplied to the second vacuum column 100 at 315-350 ° C (600-662 ° F). In one aspect, the first pitch stream in line 98 can be directly fed to the second vacuum column 100 without being exposed to heating or cooling equipment. In other words, as long as line 98 feeds the raw materials to the second vacuum column 100, no heating or cooling apparatus is required. However, some heating or cooling may be necessary. Alternatively, in one aspect, heat is supplied to the second vacuum column 100 using hot oil or water vapor. As a consequence, the temperature of the first pitch stream 98 of the pitch at the inlet of the second vacuum column 100, in one aspect, is no more than 50 ° C. higher or lower than the temperature of the first stream of 98 pitch from the bottom stream at the outlet of the first vacuum column 90.

The second vacuum column 100 is located after the bottoms stream of the first vacuum column 90 and is associated with it. In the second vacuum column 100, a pressure of from 0.1 to 3.0 kPa (1-23 Torr) is maintained, preferably from 0.2 to 1.0 kPa (1.5-7.5 Torr), and a vacuum distillation temperature of 300 up to 370 ° C, which corresponds to the atmospheric equivalent for the run between heavy vacuum gas oil and pitch from 454 to 593 ° C (850-1100 ° F), mainly from 482 to 579 ° C (900-1075 ° F) and, most preferably, 510 to 552 ° C (950-1025 ° F). The second vacuum column 100 is located after the first vacuum column 90, fractionation section 50 and the GSF reactor 20 and is associated with them.

The second vacuum column 100 may be a traditional vacuum column, or it may have a special function for driving the SH from the pitch by forming a pitch film, which facilitates the evaporation of lower boiling components from the pitch. Special film-forming evaporators are able to stimulate a sufficiently rapid evaporation of SH in order to avoid coking. The film-forming evaporators can be a stripping evaporator, a thin-film evaporator, a film evaporator, a falling film evaporator, an ascending film evaporator and a scraper evaporator. Some of these film-forming evaporators may include a movable part for updating the pitch surface in the second vacuum column 100. Other types of thin-film evaporators may also be suitable. For example, a thin-film evaporator (TFE) heats the pitch on the inner surface of a heated pipe until the SH begins to evaporate. The pitch is held in the form of a thin film on the inner surface of the pipe using a rotating blade with a fixed gap. VG pairs are then liquefied on the pipes of the condenser cooler. A film evaporator (WFE) differs from a thin film evaporator in that it uses a hinged blade with a minimum clearance from the inner surface, which mixes the current pitch, facilitating separation. Both in the case of a thin-film evaporator and in the case of WFE, the pitch enters the device tangentially above the heated inner pipe and is evenly distributed along the inner periphery of the pipe with a rotating blade. The pitch descends along the wall in a spiral, while the waves traveling in front created by the rotor blades generate a very turbulent flow and an optimal heat flow. VG quickly evaporates and the vapors can move parallel or countercurrent to the pitch. In the case of a simple design, TFE and WFE, the SH can condense in a condenser located outside the evaporator, but if possible close to it. Another type of TFE and WFE is a molecular distillation device that has an internal capacitor. The scraper evaporator works in a manner similar to the WFE principle. However, the scraper evaporator is designed not only to maintain a thin film on the internal heated surface, but also to protect the pitch film on the heated surface from overheating by frequent removal of the scraper.

In an evaporator with a falling film, the pitch enters the evaporator from above and is evenly distributed in the heating pipes. A thin film enters the heating pipes and moves downward at boiling point, partially evaporating. An inert gas, such as water vapor, can be used to heat pipes outside. Both the pitch and the VG pairs move down the pipes into the lower separator, in which the vapor VG is separated from the pitch.

The rising film evaporator operates on a thermosiphon principle. The pitch enters the bottom of the heating pipes heated by steam supplied to the outer surface of the pipes. As the pitch heats up, VH pairs begin to form and rise upward. The upward force of this evaporating SH is causing the liquid and vapor to move upward in a parallel flow. At the same time, the formation of VG vapor intensifies and the ascending pitch is compressed into a thin film on the pipe walls. Parallel upward movement against gravity has a beneficial effect on the creation of a high degree of turbulence in the pitch, which contributes to heat transfer and inhibition of coke.

In one aspect, the special vacuum column 100 for forming a thin film may be a stripper supplied by Artisan Industries of Waltham, Maryland. The second vacuum column in the form of a stripping evaporator is shown in figure 1. The first pitch stream 98 may pass through an optional pre-evaporator 102, which may be an ascendant film evaporator to vaporize the bulk of the SH from the pitch. The stripping evaporator can operate without a pre-evaporator 102. Water vapor or other inert gas flows upward from the pre-evaporator 102 from the steam collector 104, from which bottom condensate flows. The pitch and the VG enter the flashing section 108 with an increased diameter of the stripping evaporator along line 106. To release condensable materials, the vaporous VG can exit the top of the stripping evaporator through a mist eliminator. Steam leaves line 110 and enters condenser 112 and possibly into accumulator 114. Vacuum is created in condenser 112, possibly using multi-stage mixing ejectors or some other suitable device. In one aspect, line 116 picks up the SH, primarily a heavy SH, which is recycled to the GSF reactor 20 through line 8. Accordingly, the GSF reactor 20 is located after the overhead of the second vacuum column 100 and is associated with it. A portion of the heavy HB in line 116 can be taken as pure product via line 124. The pitch in the stripper evaporator 100 cascades down through heated or unheated trays such as disk-tube trays, while the remaining volatile materials are vaporised by upward steam. Plates create at each stage a new thin liquid film, updating the surface of the pitch film for evaporation and stripping. In one aspect, the trays can limit the internal cavities associated with the heating fluid from line 126 to indirectly heat the pitch moving through these trays. The heating fluid exits the second vacuum column 100 through a heating line 128. An inert gas, such as water vapor or nitrogen, can be bubbled through the column from line 118 to distill the pitch and further enhance mass transfer through the column. The second pitch stream is removed from the vacuum column 100 via line 120 and contains less than 14 wt.% HH, preferably not more than 13 wt.% HH. In this context, less than 14 wt.%, In one aspect, not more than 13 wt.% And preferably not more than 10 wt.% From the second pitch stream in line 120 from the second vacuum residue boils at 538 ° C (1000 ° F) or lower . Moreover, less than 14 wt.%, In one aspect, not more than 13 wt.% And mainly not more than 10 wt.% From the second pitch stream in line 120 boils in the range from 300 ° C (572 ° F) to 538 ° C ( 1000 ° F). In this aspect, at least 1 wt.% Of the second pitch stream in line 120 is HB, which boils at 538 ° C (1000 ° F) or lower. The second pitch stream in line 120 also contains hydrogen at a concentration of 8 wt.% Or lower, preferably 6 wt.% Or lower and, as a rule, at least 4 wt.% On an ash-free basis (without inorganic matter). The second pitch stream may have a density of at least 1.1 g / cm ³ , preferably at least 1.15 g / cm ³ and, as a rule, not higher than 1.3 g / cm ³ on an ash-free basis (without inorganic matter). The second pitch stream may also contain from 1 to 10 wt.% Toluene insoluble organic residue. The second vacuum column 100 is able to extract from the pitch up to 15 wt.% VG. This recovered SH is exited from the vacuum column 100 via an overhead line 110 and can be recycled through lines 116, 8, 16 and 18 to the GSF reactor 20.

The second pitch stream in line 120 of the vacuum residue can be diverted directly to granulation machine 130. In one aspect, in order to prepare the pitch for granulation, it is not necessary to control the temperature of the pitch in line 120 by heat exchange. A particularly useful pelletizing machine 130 is a pelletizer called Rotoformer, supplied by Sandvik Process Systems of Sandviken, Sweden, which produces a hemispherical particle called a tablet. Other granulating machines can be belt melter granulators, underwater melter cutters, die plate extruders, granulating systems, spray dryers, and the like. The resulting granules must have a rounded or partially rounded appearance, allowing them to move freely in bulk in processing and transporting systems. Rounded or partially rounded granules are less susceptible to sticking together because they have fewer contact points and are less prone to dust because they do not have sharp edges of scaly material.

The pelletizing granulating machine has a heated cylindrical stator 134 to which molten pitch is supplied from the second pitch stream 120 or storage tank 132. The granulating machine 130 is located after the second vacuum column 100 and connected to it via line 120. The rotating perforated cylindrical wall 136 rotates concentrically relative to stator 134, forming particles, or pitch tablets by forcing through holes in a perforated wall 136. Tablets are laid out over the entire working width of the conveyor tape 138, which, in one aspect, is made of stainless steel. The heat generated by the solidification and cooling of the falling tablets is transferred through a strip 138, which is cooled by indirect heat exchange with cooling media, such as water sprayed under the tape from line 140. The sprayed cooling water is collected in tanks and returned to line 142 to the water cooling system without contact with particles of pitch. The heated re-feed drum can push the excess pitch remaining in the holes of the rotating cylindrical wall 136 to the position from which it re-drops onto the tape 138. The tape 138 transfers the tablets to the collector 144. The pitch tablets can now be easily handled in bulk and transported to the consumer. Pitch tablets can now be stored or transported without the need for further forced cooling. The tablets will not stick together because enough HH has been separated from the pitch to raise the softening onset temperature above the highest expected transport temperature. The highest expected transport temperature will necessarily depend on the climatic conditions on the route and the type of container. According to the International Safe Transit Association, Ocean Container Temperature and Humidity Study, Preshipment Testing Newsletter (2d Quarter 2006), a reliable global maximum of 66 ° C (150 ° F) can be estimated.

Figure 2 shows an alternative process flow diagram of the present invention, in which pitch along line 150 from the first pitch stream in line 98 is returned to the GSF reactor 20. Figure 2 differs from Figure 1 only by the presence of pitch recycling line 150, which diverts part of the first a pitch stream 98, controlled by a control valve 140, bypassing the vacuum column 100 for connecting to line 116 and feeding to line 8. Accordingly, the GSF reactor 20 is located after the first vacuum column 100 and is connected to its bottom residue. All other aspects of the embodiment of FIG. 2 are the same as in FIG. At least a portion of the first pitch stream may in some cases be recycled as part of the feed for the GSF reactor 20 in line 8. The remaining catalyst particles from the GSF reactor 20 in the stream exiting the slurry hydrocracking stream via line 28 will be present in the first pitch 98 stream . Part of the catalyst can conveniently be returned as recycle to the GSF reactor 20 along with part of the first pitch stream. This alternative should preserve the GSF catalyst. The remainder of the first pitch stream in line 98 is supplied to the second vacuum column 100 via line 146. In this alternative aspect, the first vacuum column 90 may be a flash column without heat or cooling.

Example

To determine which pitch materials can be cured and transported as the highest temperature that could affect the pitch materials during transportation, a temperature of 66 ° C (150 ° F) was adopted, taking into account the limits of safe operation. The pitch materials should be suitable for transporting to the indicated maximum temperature without starting sticking. In other words, the temperature of the onset of softening of the pitch should be above 66 ° C (150 ° F).

The methodology for using a thermomechanical analyzer is similar to the method for measuring the densities of a powdery molding polymer described by McNally, G. and McCourt, M., density measurement of thermoplastic powders during heating and cooling cycles using thermal mechanical analysis (measuring the density of thermoplastic powders during heating-cooling cycles with using mechanical analysis), ANTEC 2002 Conference Proceedings, 1956-1960. To measure the temperature of the onset of melting and the melting temperature, the Q400 thermomechanical analyzer model from TA Instruments of New Castle, Delaware was used. 10 mg of manually ground unsintered pitch powder is introduced into a 7 mm aluminum cup. A layer of powder is coated with an aluminum cover plate. A quartz plunger on the cap measures the position of the cap. The powder is exposed to a load of 5 g and is heated at a rate of 5 ° C / min. As the temperature rises, the pitch softens and settles. Tabular data of the dependence of the position on temperature is collected and a graph of the dependence of the first derivative change in deviation from temperature change at temperature intervals of 5 ° C is built. The melting point is the temperature of the maximum of the negative displacement, when the rate of thermal expansion overlaps the sedimentation rate of the powder, which looks like a distinct sharp saddle on the speed graph. This saddle is distinct, because the powdery powder after shrinkage begins to expand with increasing temperature, now in a liquid state. The onset of melting is defined as a distinct deviation of 1% of the first derivative relative to the saddle.

The melting onset temperature at 1% of the shape change, denoted by T (1%), is determined by the following way:

T (1%) is the temperature at which (ZZ _liq ) / (Z ₀ -Z _liq ) = 0.01 (1)

Where

Z = position measured at temperature T;

Z ₀ = initial position of the plunger with the sample at room temperature; and

Z _liq = position at the melting point, which is the peak on the velocity graph.

To illustrate the method required to obtain a non-sticky, free-flowing pitch granule, seven residual pitch products were prepared from a mixture of the heavy product of a hydrocracking reactor in suspension phase. The starting material for each residual pitch product was a heavy fraction of products obtained after 87 wt.% Conversion, defined as material boiling above 524 ° C (975 ° F), converted to material boiling below 524 ° C (975 ° F), using hydrocracking in the suspension phase of the bottom residue of the vacuum column. The bottom residue of the vacuum column from cold-mined bitumen from the Peace River (Seal) formation near Slave Lake, Alberta, Canada. This bituminous residue was subjected to hydrocracking in a slurry phase at 13.79 MPa (2000 lb / ⁱⁿ²⁾ in the presence of hydrogen using a catalyst based on iron sulphate in the reactor with continuous stirring. The hydrocracked products exiting the reactor were vaporized once to remove products lighter than the middle distillate and freed from hydrogen and all non-condensable products. The source material for further fractionation will hereinafter be referred to as “heavy tails”.

Sample 1 is a pitch tablet obtained by traditional vacuum tailings fractionation. The cured tablet of sample 1 did not move freely and was noticeably sticky at room temperature. The onset of shape change, measured using a thermomechanical analyzer, was noted at 44 ° C. Sample 1 was not acceptable for working with it in bulk and for transportation.

Sample 2 is a clarified pitch obtained by the following method: heavy tails were left to settle in the tank, after which the liquid not containing solid material was subjected to single evaporation in vacuum at 0.7 kPa (5 Torr) and 380 ° C. The clarified heavy subjected to a single evaporation in vacuum, the liquid was not subjected to further processing. It was not clearly sticky and had a softening start point of 72.5 ° C, which was slightly higher than the maximum transport temperature. Thus, material 2 is acceptable at the limit.

Sample 3 is an oil-free sludge obtained from the heavy tailing process, which was used to obtain sample 2. The physical separation consisted of draining the oil from the vaporized liquid once on a sieve plate, while the volatiles were removed as a result of spontaneous evaporation. After that, the oil-free sludge was subjected to vacuum evaporation in a falling film evaporator in high vacuum at 0.3 kPa (2 Torr), but was not subjected to additional processing. Like sample 1, it was clearly sticky and also could not move freely. The softening start point, 52.7 ° C., for material 3 is not acceptable. The content of HB in it, determined by the mass balance, amounted to 14 wt.%.

Samples 4 and 5 are samples in which the heavy tails were subjected to vacuum fractionation in a laboratory distillation apparatus of periodic action in high vacuum with magnetic stirring. Samples 4 and 5 were acceptable, since they have a higher softening start temperature than the maximum transport temperature. However, sample 5 was heated to a temperature of 320 ° C to remove a larger amount of SH. At this temperature, there was a slight thermal cracking. Partial pyrolysis of pitch material can increase the temperature of the onset of softening. However, in this case, pitch is more difficult to work with because of its higher viscosity in the liquid state, and high temperature will lead to the formation of coke on heat-exchanging surfaces. In addition, thermal cracking will lead to a greater volume of gases, which will quickly exceed the capacity of the vacuum system, especially at low absolute pressures.

Samples 6 and 7 were prepared in two stages: first, fractionation in vacuum and then, in the second stage, placement in a film evaporator operating at a single-temperature internal temperature of 300 ° C and a pressure of 0.1 and 0.3 kPa (0.7 and 2.5 Torr), respectively. Samples 6 and 7 were then granulated by re-melting and molding into 7 mm partially rounded tablets on a Sandvik Rotofbrmer. The tablets were non-sticky and free-flowing without any sticking even at 100 ° C, thereby confirming that the granular material can be processed at temperatures above any possible transport temperature.

The table below shows the test results. The proportion of HB is determined by the pitch fraction, which boils at 538 ° C (1000 ° F) or lower. The pitch with a share of VH less than 14 wt.% Has an acceptable softening start temperature for processing in the mass as a whole.

Table Sample No. Melting point, ° С Softening start point, ° С The share of VG, wt.% one 86.1 43.7 eighteen 2 96.4 72.5 13 3 88.1 52.7 fourteen four 116.5 72,2 2 5 169.5 118.5 2 6 153.5 113.8 one 7 143.7 95.0 1,5

Assume that the pitch products in samples 1-7 should have a hydrogen concentration of 5 wt.% And a density of 1.2 g / cm ³ on an ash-free basis (without inorganic matter).

It is believed that using the above description and without further explanation, one skilled in the art can fully realize the present invention. The specific preferred embodiments given are, therefore, to be regarded only as illustrative and not in any way limiting the rest of the disclosure.

In the above description, unless otherwise indicated, all temperatures are given in degrees Celsius, and all parts and percentages are given by weight.

From the above description, a person skilled in the art can easily draw on the main characteristics of the present invention and, without departing from their essence and scope, can make various changes and modifications to the invention in order to adapt it for various applications and conditions.

Claims (10)

1. A method of converting heavy hydrocarbon feeds into lighter hydrocarbon products and pitch separation, comprising:
hydrocracking said heavy hydrocarbon feedstock suspended with a granular solid material in the presence of hydrogen in a hydrocracking reactor, resulting in a hydrocracked stream including vacuum gas oil (SH) and pitch;
separating at least a portion of said hydrocracked stream in a first vacuum column, resulting in a first pitch stream and a first HB stream; and
separating at least a portion of said first pitch stream in a second vacuum column, resulting in a second pitch stream and a second SH stream. 2. The method according to claim 1, in which the pressure at the inlet to the first vacuum column is higher than the pressure at the inlet to the second vacuum column. 3. The method of claim 1, further comprising molding the pitch in said second pitch stream into non-sticky solid particles at temperatures up to 66 ° C (150 ° F). 4. The method according to claim 1, in which the paraffin wax stream, taken below the shoulder of the heavy GV, is returned as a recycle to the hydrocracking reactor. 5. The method of claim 1, wherein the pitch from the second vacuum column has a softening start temperature of at least 66 ° C (150 ° F). 6. The method according to claim 1, further comprising recirculating said first pitch stream to a hydrocracking step. 7. The method according to claim 1, further comprising recirculating the second GH stream to the hydrocracking stage. 8. A device for converting heavy hydrocarbon feeds into lighter hydrocarbon products and separating pitch, including:
a suspension phase hydrocracking reactor for contacting said heavy hydrocarbon feed with a particulate solid material;
a first vacuum column in communication with said slurry hydrocracking reactor; and
a second vacuum column in communication with said first vacuum column. 9. The device of claim 8, wherein said second vacuum column is a film-forming evaporator. 10. The device of claim 8, wherein said second vacuum column includes a moving part that updates the surface of the material in the second vacuum column.

Images