CN100489061C - Integrated process for the conversion of feedstocks containing coal into liquid products - Google Patents

Abstract

Integrated process for the conversion of feedstocks containing coal into liquid products by the joint use of at least the following seven process units: coal liquefaction (CL), flash or distillation of the product obtained from the liquefaction (F), extraction with a solvent to remove the ashes (SDAsh), distillation to separate the solvent (RS), hydroconversion with catalysts in slurry phase (HT), distillation or flash of the product obtained from the hydroconversion (D), deasphalting with a solvent (SDA).

Description

Integrated method for conversion of coal-bearing feedstock to liquid products

The present invention relates to an integrated process for the conversion of coal-containing feedstock to liquid products.

The direct coal liquefaction process is based on hydrotreating, which enables the hydrogen/carbon ratio to be increased from 0.7-0.8 to values greater than 1 and higher than typical for petroleum-derived hydrocarbon mixtures.

This is the partial destruction of the organic structure of coal under hydrogenation conditions. Along with the liquid product also gases and solids are formed, the amount of which varies depending on the feedstock to be treated, the operating conditions and the type of process.

In general, the liquefaction process is based on a fundamental thermal reaction that enables the formation of free radicals that can be stabilized by hydrogen, whose role is to avoid the reverse degradation of these free radicals to give bulky inactive molecules, and based on a catalytic hydrogenation reaction , which reduces molecular complexity by breaking multiple chemical bonds between carbon atoms and other carbon atoms, oxygen, nitrogen, and sulfur.

These two reactions can be carried out in one step and in two steps.

Regardless of the method used, the result of the reaction is the destruction of the more complex hydrocarbon structure with concomitant reduction or, where appropriate, removal of oxygen, nitrogen and sulfur in the form of water, amines and hydrogen sulfide.

The reaction is carried out in the presence of a solvent, usually a solvent produced by the process itself. The solvent plays an important role in the conversion process because it can extract hydrogen-rich products and dissolve complex molecules formed by heat, and can also act as a hydrogen donor and hydrogen transfer material to promote the reaction. Therefore, an ideal solvent must have high solvating power (thus consisting of a strong aromatic structure with an affinity for the solute) and good hydrogen-donating properties (thus must be easy to hydrogenate and release accepted hydrogen to coal) .

The products can be obtained from the liquefaction process of refined coal, which is still solid at room temperature, with low sulfur and ash content, into light liquid products such as gasoline. In the former case, with higher energy performance and weight yield, as the hydrogenation depth increases, the hydrocracking reaction becomes more and more significant, and the quality of the liquid product increases but the yield decreases.

The methods of coal liquefaction to medium/light products studied so far can be represented by the following routes in terms of synthesis and flow:

One-step high-depth liquefaction method;

• Several steps of liquefaction at different depths.

In the former case, thermal and catalytic reactions are carried out in a single reactor, and the reaction conditions are a compromise between different optimal conditions for the two reactions; usually deep hydrocracking is carried out, and the products obtained are fine and heavy between liquid and unreacted solids Distills well during separation, which can be achieved by vacuum flash evaporation.

A disadvantage, however, is the high yield of undesired product gases and thus considerable hydrogen consumption.

With a multi-step process, it is possible to operate under the optimum conditions of separate thermal and catalytic reactors (especially the first liquefaction step can be carried out at low depth by achieving the conversion of coal in the liquid extract, since there is less hydrogenation cracking reaction, so the gas yield is low), but since most of the products cannot be distilled out, more complex vacuum solid/liquid separation techniques such as anti-solvent or filtration must be used.

Finally, after solid/liquid separation, the extract is subjected to a subsequent hydrocracking step under controlled catalytic conditions to lighten the product.

The overall advantage is better utilization of hydrogen at low consumption and high processing flexibility, resulting in a wider range of products to choose from.

Regardless of whether the coal liquefaction reaction is carried out in one-step or multi-step manner, the resulting coal liquid is rich in nitrogen, sulfur and high-density extremely strong aromatic compounds, so it must go through ad hoc processing units (hydrogenation by conventional technology) cracking step) undergoes heavy re-refining to produce distillates with commercial properties.

It has now been found that conversion of the DAO fraction can be maximized by subjecting liquids obtained from coal liquefaction to certain further conversion treatments using hydroprocessing techniques already used in heavy crude conversion processes or residue distillation processes.

Hydrotreating of heavy crude oil conversion process or residual oil distillation process is to treat the feedstock in the presence of hydrogen and a suitable catalyst.

The recent popular hydroconversion technology in the market uses fixed-bed or ebullated-bed reactors, and uses one or more transition metals (Mo, W, Ni, Co, etc.) supported on silica/alumina (or equivalent materials) catalyst.

Fixed bed technology has significant problems with heavy feedstocks, especially those containing high percentages of heteroatoms, metals and asphaltenes, because these contaminants deactivate the catalyst very quickly.

Ebullated bed technology has been developed and commercialized for processing these feedstocks, which offers interesting properties, but is complex and expensive.

Hydroprocessing technology, in which the catalyst operates in a dispersed phase, offers an attractive solution to the disadvantages associated with the use of fixed or ebullating bed technologies. In fact, the slurry process not only has wide raw material adaptability, but also has good performance in terms of conversion rate and product quality improvement, so from a technical point of view, at least in principle, the technology is simpler.

Slurry technology is characterized by the presence of catalyst particles of very small average size and efficiently dispersed in the medium, therefore, the hydrogenation process is simpler and can be more efficient at all points of the reactor. Coke formation is significantly reduced and the quality of the raw material is much improved.

The catalyst can be dosed in powder form sufficiently reduced in size or as an oil-soluble precursor. In the latter case, the active form of the catalyst (usually a metal sulfide) is formed in situ by thermal decomposition of the compound used during the reaction or after appropriate pretreatment.

The metal component of the dispersed phase catalyst is generally one or more transition metals (preferably Mo, W, Ni, Co or Ru). Molybdenum and tungsten have much more satisfactory properties than nickel, cobalt or ruthenium, even better than vanadium and iron (N. Panariti et al., Appl. Catal. A: Gen. 2000, 204, 203).

Although the use of dispersed phase catalysts solves most of the problems mentioned in the above techniques, it still has deficiencies, mainly the service life of the catalyst itself and the quality of the products obtained.

In fact, the usage conditions of these catalysts (precursor type, concentration, etc.) are very important factors from the viewpoint of economy and impact on the environment.

Catalysts can be used in low concentrations (hundreds of ppm) in a "single-pass" process layout, but in this case the modification of the reaction product is usually insufficient (A. Delbianco et al., Chemtech, November 1995, 35). When operating with very high activity catalysts (such as molybdenum) and high catalyst concentrations (thousands of ppm metals), the resulting product is of much better quality, but it is necessary to recycle the catalyst.

The catalyst leaving the reactor can be recovered by separating it from the hydrotreated product (preferably obtained from the bottom of the distillation column downstream of the reactor) by conventional methods such as decantation, centrifugation or filtration (US-3240718, US-4762812). A portion of the catalyst is recycled back to the hydrogenation process without further treatment. However, catalyst recovered using known hydroprocessing methods is generally less active than fresh catalyst, and appropriate regeneration steps are necessary to restore catalytic activity and to recycle at least a portion of said catalyst back to the hydroprocessing reactor. Furthermore, these methods of catalyst recovery are expensive and extremely complicated from a process point of view.

The level of conversion achievable by all of the above hydroconversion processes depends on the feedstock and the type of process used, but in any case some unconverted residue (here referred to as tar) is produced at the limit of stability, depending on the situation The amount may vary from 15% to 85% of the starting material. The product is used to produce fuel oil, bitumen or as a feedstock for gasification processes.

In order to increase the overall conversion level of the resid cracking process, various schemes involving recycling more or less significant amounts of tar in the cracking unit have been proposed. In the case of a hydroconversion process with catalyst dispersed in the slurry phase, the recycling of the tar allows recovery of the catalyst to the extent of the process described by the same applicant in IT-95A001095, which enables recovery of the catalyst without further regeneration The steps are recycled to the hydrotreating reactor, and at the same time, high-quality product products are obtained under the condition of no residue oil (residue-free refinery unit).

This method includes the following steps:

Mixing heavy crude oil or distillation residue with a suitable hydrogenation catalyst and feeding the resulting mixture into a hydrotreating reactor filled with hydrogen or a mixture of hydrogen and _H2S ;

Sending the stream comprising the hydrotreating reaction product and the dispersed phase catalyst to the distillation zone to separate the volatile fraction (naphtha or gas oil);

the high boiling fraction from the distillation step is fed to the deasphalting step, thus producing two streams, one comprising deasphalted oil (DAO) and the other comprising asphaltenes, dispersed phase catalyst and possibly coke and enriched in metals from initial raw materials;

• Recycle at least 60%, preferably at least 80%, of the metal-rich stream comprising asphaltenes, dispersed phase catalyst and possibly coke to the hydrotreatment zone.

As described in patent application IT-MI2001A-001438, it was later found that, in the case of the above-mentioned processes, the upgrading of heavy crude oil or oil sands bitumen into complex hydrocarbon mixtures for further conversion into distillates When raw materials for the process, a different layout than the process described above can be used.

The heavy feedstock conversion method described in patent application IT-MI2001A-001438 uses the following three process units in combination: a hydroconversion unit (HT) with a catalyst in a slurry phase, a distillation or flash unit (D), a deasphalting unit ( SDA), characterized in that the three units start operating with a mixed stream of fresh raw material and recycled material, using the following steps:

Sending at least a portion of the heavy feedstock to a deasphalting section (SDA) in the presence of a solvent to produce two streams, one consisting of deasphalted oil (DAO) and the other consisting of asphaltenes;

Mixing the asphaltenes stream with the remainder of the heavy feedstock not sent to _the deasphalting zone and a suitable hydrogenation catalyst and sending the resulting mixture to a hydrotreating reactor (HT );

Sending the stream containing the hydroprocessing reaction product and the dispersed phase catalyst to one or more distillation or flashing steps (D), whereby volatile fractions are separated, including gases formed in the hydroprocessing reaction, naphtha oil and gas oil;

At least 60%, preferably at least 80% of the distillation residue (tar) or liquid leaving the flash unit comprising dispersed phase catalyst, metal-rich sulphides from the feedstock demetallization step and possibly coke and various carbonaceous residues More preferably at least 95% is recycled to the deasphalting zone.

Flushing of the asphaltene stream leaving the deasphalting section (SDA) is usually required to ensure that these elements do not accumulate too much in the hydrotreating reactor and, in the event of catalyst deactivation, to remove a portion of the catalyst and replace it with fresh catalyst. However, this is generally unnecessary if the catalyst retains its activity for a long period of time, and in any case where flushing is necessary for the above reasons, it is clear that some catalysts must be discarded even if they are far from being completely deactivated. Furthermore, although the amount of purge streams (0.5-4% relative to feedstock) is extremely limited compared to other hydrotreating processes, they still present considerable utilization or disposal problems.

When it is necessary to use the heavy fraction of the complex hydrocarbon mixture (distillation column bottoms) produced by the process as feedstock for a catalytic cracking unit carrying out simultaneous hydrocracking (HC) and fluid catalytic cracking (FCC), the The above application is particularly applicable.

The combination of catalytic hydrogenation unit (HT) and extraction process (SDA) enables the production of deasphalted oil with low content of impurities (metals, sulfur, nitrogen, carbonaceous residues), which can be more easily processed in the catalytic cracking process. be processed in.

However, another aspect to consider is that the naphtha and gas oil directly produced by the hydrotreating unit still contain many impurities (sulphur, nitrogen...) which must in any case be reprocessed in order to produce the final product.

The object of the present invention, that is, an integrated process for converting coal-containing feedstock into liquid products, can be achieved by combining at least the following seven process units: a coal liquefaction unit (CL), a unit (F) for products obtained from a distillation or flash liquefaction unit, a solvent Extraction to remove ash (SDAsh), distillation to separate the solvent (RS), slurry phase catalyst hydroconversion (HT), distillation or flash hydrogenation unit (D), Solvent deasphalting unit (SDA), is characterized in that comprising the steps:

Feedstock containing coal is fed to one or more direct coal liquefaction steps (CL) in the presence of a suitable hydrogenation catalyst;

sending the stream containing the product from the coal liquefaction reaction to one or more distillation or flashing steps (F) to obtain a gaseous stream and a liquid stream;

sending the liquid stream to the solvent extraction step (SDAsh), thereby obtaining an insoluble stream consisting of the mineral matter present in the raw material and unreacted coal and a liquid stream consisting of the obtained liquefied coal and the solvent used;

sending the liquid stream consisting of the resulting liquefied coal with the solvent used to one or more distillation steps in order to substantially separate the solvent contained in the liquid stream for recycling back to the solvent extraction step (SDAsh);

mixing the stream consisting essentially of liquefied coal and the asphaltenes-containing stream obtained in at least part of the deasphalting unit with a suitable hydrogenation catalyst and sending the resulting mixture to a hydrogenation process where hydrogen or a mixture of hydrogen and _H2S is introduced Hydrogen treatment reactor (HT);

· passing the stream containing the hydroprocessing reaction product and the dispersed phase catalyst to one or more distillation or flashing steps (D) to separate the different fractions from the hydroprocessing reaction;

Sending at least a portion of the distillation residue (tar) or liquid containing dispersed phase catalyst, metal-rich sulfides from the demetallization of the feedstock and optionally coke leaving the flash unit to a deasphalting zone (SDA) in the presence of solvent, either A liquid stream, at least in part consisting essentially of liquefied coal, is also selected as feed, so that two streams are obtained, one consisting of deasphalted oil (DAO) and the other consisting of asphaltenes.

The coal contained in the feedstock to be subjected to the liquefaction step may be raw or optionally beneficiated by known coal beneficiation techniques.

The coal-containing feedstock is preferably a feedstock consisting essentially of coal.

The suitable hydrogenation catalyst present in the liquefaction step (CL) can be recovered at least in part, recycled back from units downstream of said step (e.g. by means of the asphaltene-containing stream obtained from the deasphalting unit (SDA) or by means of a portion leaving the flash unit (D) Distillation residues (tars) or liquids containing dispersed phase catalysts, metal-rich sulfides from demetallization of feedstocks and possibly coke).

A feedstock consisting essentially of coal is preferably slurried in a hydrocarbon matrix derived from asphaltene-containing asphaltenes obtained from a downstream unit of the liquefaction step (CL), preferably a deasphalting unit (SDA-) and a hydrotreating step (HT) part of the stream of catalyst used and/or part of the stream consisting of deasphalted oil (DAO) resulting from the deasphalting step (SDA).

In the distillation step (RS) of the liquid stream consisting of the liquefied coal and the solvent used, a further stream is optionally separated as a fraction and optionally fed in whole or in part to the distillation or flash unit (D) separated in the light distillate.

The direct liquefaction process of a coal-containing stream can be carried out using one of various known coal liquefaction methods.

Preferably by mixing a coal-containing stream with an aromatic solvent in an amount in the range of 20-80% of coal and a suitable dispersed phase catalyst, at a temperature in the range of 360-440°C, a hydrogen pressure of 3-30MPa and less than or equal to Operating at a residence time of 4 h, the stream was subjected to direct liquefaction.

The aromatic solvent used is preferably derived at least partly from one or more of the following recycle streams:

part of the stream consisting of deasphalted oil (DAO) produced in the deasphalting step (SDA);

· at least a part of the asphaltene-containing stream produced by the deasphalting step (SDA) and the dispersed phase catalyst used in the hydrotreatment step (HT);

part of the middle and heavy fractions (middle and heavy distillates) obtained from the distillation or flash unit (D);

Part of the solvent separated from the distillation step (RS) downstream of the deashing unit (SDAsh);

- Part of another stream separated as a fraction from the distillation step (RS) downstream of the deashing unit (SDAsh).

The solvent extraction step (SDAsh) for deashing is preferably carried out in the presence of a suitable aromatic solvent at a temperature in the range 150-350°C and a pressure in the range 20-60 atmospheres.

In terms of process in a broad sense, high boiling point materials selected from heavy crude oil, distillation residues, heavy oils from catalytic processes, thermal tars, oil sands bitumen, various coals and some other hydrocarbon sources known as black oils can also be used The heavy feedstock is added to the feedstock consisting of coal to be sent to the liquefaction unit (CL) and/or to the liquid stream consisting of liquefied coal to be sent to the hydrotreatment step (HT).

In addition to the above steps forming an integrated process, there may also be a second post-treatment hydrogenation section for treating the C ₂ -500°C fraction, preferably the C ₅ -350°C fraction, from the high pressure separation section upstream of the distillation process.

In this case, the stream containing the hydroprocessing reaction product and the dispersed phase catalyst is subjected to a separation pre-step operated at high pressure to obtain a stream of light fractions before being sent to one or more distillation or flashing steps and a heavy fraction, only said heavy fraction is sent to said distillation step (D).

The light fraction from the high pressure separation step can be sent to the hydrotreating section to produce a lighter fraction containing C ₁ -C ₄ gases and H ₂ S and a lighter fraction containing hydrotreated naphtha and gas oil. heavy fraction.

The method of inserting a second post-treatment hydrogenation section of the _C2-500 °C component, preferably the _C5-350 °C component, exploits the possibility of using this fraction with hydrogen at a higher pressure close to the hydrotreating reactor, enabling Get the following benefits:

It can produce fuels that can meet the most stringent sulfur content specifications (<10-50ppm sulfur) from very sulfur-rich oil feedstocks, and other characteristics of diesel engine gas oils such as density, polycyclic aromatic hydrocarbon content and sixteenth Improvement in alkane number;

·The produced distillate has no stability problem.

The post-hydroprocessing process on a fixed bed is the pre-separation of the reaction output from the hydroprocessing reactor (HT) by means of one or more separators operating at high pressure and high temperature. The heavy part taken from the bottom is sent to the main distillation unit, and the part taken from the top, that is, the C ₂ -500°C component, preferably the C ₅ -350°C component, is sent to the second treatment zone where high-pressure hydrogen exists, and the reactor is a fixed bed reactors, with typical desulfurization/dearomatization catalysts, in order to obtain very low sulfur and nitrogen content, low overall density products, with increased cetane number for the gas oil fractions of interest.

The hydrotreating section usually consists of one or more reactors in series, and then the product of this system can be further fractionated by distillation to produce fully desulfurized naphtha and diesel gas oil meeting fuel specifications.

The fixed-bed hydrodesulfurization step usually uses a typical gas oil hydrodesulfurization fixed-bed catalyst, which may be a catalyst mixture or a set of reactors equipped with various catalysts with different properties. By significantly reducing sulfur and nitrogen content, increase the degree of hydrogenation of raw materials, thereby reducing the density of gas oil fractions and increasing the cetane number, and at the same time reducing the formation of coke, so that the light components can be deeply refined.

The catalyst usually contains an amorphous part based on alumina, silica, silica-alumina and mixtures of various inorganic oxides, on which the hydrodesulfurization components are deposited (by various means) together with the hydrogenation reagent. Catalysts based on molybdenum or tungsten, in addition to nickel and/or cobalt deposited on an amorphous inorganic material support, are typical catalysts for this type of operation.

The hydrogenation post-treatment reaction is carried out at an absolute pressure slightly lower than the pressure of the first hydrotreatment step, usually 7-14MPa, preferably 9-12MPa; the hydrodesulfurization temperature is 250-500°C, preferably 280-420°C, The temperature generally depends on the desired level of desulfurization. The space velocity is another important variable when the quality of the product obtained is to be controlled: it may be from 0.1 to 5 hours ⁻¹ , preferably from 0.2 to 2 hours ⁻¹ .

The amount of hydrogen mixed with the raw materials is 100-5000Nm3/m3, preferably 300-1000Nm3/m3.

In addition to the above-mentioned steps leading to an integrated process, there may optionally be another second work-up section of the flush stream, used alone or together with a work-up hydrogenation section.

Said further second post-treatment stage is post-treatment of the purge stream in order to significantly reduce its amount, allowing at least a portion of the still active catalyst to be recycled back to the hydrotreatment reactor.

In this case, the asphaltene-containing stream from the deasphalting section (SDA), called the purge stream, is sent to a treatment section with a suitable solvent, where the product is separated into a solid and a liquid remove the solvent.

Optional flush effluent (preferably 0.5-10% by volume of fresh feedstock) treatment stage deoiling steps from solvent (toluene or gas oil or other stream rich in aromatics components) and liquid components versus solid components Separate step composition.

At least a portion of said liquid components may be sent to:

Fuel pool, fed as is or after solvent separation and/or after addition of appropriate fluxing fluid;

• and/or sent as such to the hydrotreating reactor (HT).

In some specific cases, the solvent and diluent may be the same.

The solid components can be disposed of as such or, more advantageously, sent to be subjected to selectivity for transition metals or metals contained in transition metal catalysts (e.g. molybdenum) relative to other metals present in the starting residue, nickel and vanadium For) recovery treatment, and optionally recycling the transition metal (molybdenum) rich stream back to the hydrotreatment reactor (HT).

Compared with traditional methods, this composite treatment method has the following advantages:

The number of rinse components is greatly reduced;

Most of the flushing components can be converted into fuel oil by separating metals and coke;

• The amount of fresh catalyst added to the feed to the first hydroprocessing step is reduced since at least a portion of the molybdenum extracted from the selective recovery treatment step is recycled.

The deoiling step is the treatment of the purge stream, which represents a minimum asphaltene component from the deasphalting section (SDA) of the heavy feedstock first hydrotreater, using solvents that bring the maximum possible amount of organic compounds into the liquid phase while leaving metal sulfides, coke, and relatively refractory carbonaceous residues (insoluble in toluene or similar products) in the solid phase.

Given the potential for spontaneous combustion of metallic components under very dry conditions, it is reasonable to operate in an inert atmosphere containing as little oxygen and moisture as possible.

Various solvents can be well used in this deoiling step, among which mention may be made of aromatic solvents such as toluene and/or xylene blends, hydrocarbon feedstocks obtained in plants such as gas oil produced or refinery Hydrocarbon feedstocks available in for example light cycle oil from FCC unit or thermal gas oil from visbreaking/thermal cracking unit.

The operating speed can be improved by increasing the temperature and reaction time within a certain range, but for economical reasons, an excessive increase is not appropriate.

The operating temperature depends on the solvent used and the pressure conditions used, but the recommended temperature range is 80-150°C, and the reaction time can vary from 0.1-12 hours, preferably 0.5-4 hours.

The solvent/flush stream volume ratio is also an important variable to consider and can vary from 1-10 (vol/vol), preferably 1-5, more preferably 1.5-3.5.

Once the solvent and rinse streams are fully mixed phase, the output is sent to the liquid and solid phase separation section while maintaining agitation.

The operation method of this step can be one of the commonly used operation methods in industrial practice, such as decantation, centrifugation or filtration.

The liquid phase is then sent to the solvent stripping and recovery section, where the solvent is recycled back to the purge stream first treatment step (deoiling). The remaining heavies are preferred for refinery use because the stream is virtually metal-free and low in sulfur. If, for example, a treatment operation is performed with gas oil, a portion of the gas oil may remain in the heavy product, bringing it into compliance with pool fuel oil specifications.

Alternatively the liquid phase is recycled to the hydrogenation reactor.

The solid components can be disposed of as such, or otherwise treated to selectively recover catalyst (molybdenum) for recycling back to the hydroprocessing reactor.

In fact, it has been found that by adding a metal-free heavy feed such as a portion of deasphalted oil (DAO) from the plant's own deasphalting unit to the above solid phase and combining said system with acidified water (usually with a mineral acid) ) mixing, almost all of the molybdenum remains in the organic phase, while most of the other metals move into the aqueous phase. The two phases are easily separated, after which the organic phase is preferably recycled back to the hydrotreating reactor.

The solid phase is dispersed in a sufficient amount of organic phase (eg deasphalted oil from the same process) to which acidified water is added.

The ratio of the aqueous phase to the organic phase may vary from 0.3 to 3, and the pH value of the aqueous phase may vary from 0.5 to 4, preferably from 1 to 3.

A wide range of heavy feedstocks can be processed: they can be selected from heavy crude oil, oil sands bitumen, various types of coal, distillation residues, heavy oils from catalytic processes such as heavy cycle oil from catalytic cracking processes, hydroconversion Process bottoms, thermal tars (eg from visbreaking or similar thermal processes) and other high boiling feedstocks of hydrocarbon origin often referred to in the art as black oils.

In terms of process conditions in a broad sense, reference may be made to the conditions already specified in patent applications IT-MI2001A-001438 and IT-95A001095.

As described in patent application IT-95A001095, all heavy feedstocks can be mixed with a suitable hydrogenation catalyst before being sent to the hydrotreatment reactor (HT), provided that at least 60%, preferably at least 80% of the asphaltene-containing And the stream also containing dispersed phase catalyst and possibly coke and enriched in metals from the initial feedstock is recycled to the hydroprocessing zone.

As described in patent application IT-MI2001A-001438, a part of the heavy feedstock and at least mostly asphaltene-containing stream, which also contains dispersed phase catalyst and possibly coke, is mixed with a suitable hydrogenation catalyst and fed to the hydrotreatment reaction device, while the rest of the heavy raw material is sent to the deasphalting section.

As described in patent application IT-MI2001A-001438, at least a major part of the asphaltenes-containing stream (consisting essentially of said asphaltenes) is mixed with a suitable hydrogenation catalyst and fed to a hydrotreatment reactor, whereas All heavy feedstock is sent to the deasphalting section.

When only a portion of the distillation residue (tar) or liquid leaving the flash unit is recycled back to the deasphalting section (SDA), at least a portion of the remaining amount of said distillation or flash residue is optionally combined with at least a portion from the deasphalting The asphaltene-containing stream from section (SDA) is sent together to the hydrotreating reactor.

The catalyst used is selected from precursors decomposable in situ (metal naphthenates, metal derivatives of phosphoric acid, metal carbonyls, etc.) or from catalysts based on one or more transition metals such as Ni, Co, Ru, W and Mo The preformed compound of the latter is preferred because of its high catalytic activity.

The catalyst concentration ranges from 300 to 20000 ppm, preferably from 1000 to 10000 ppm, based on the concentration of the metal or metals present in the hydroconversion reactor.

The hydrotreating step is preferably carried out at a temperature of 370-480°C, more preferably 380-440°C, and a pressure of 3-30 MPa, more preferably 10-20 MPa.

The hydrogen is fed into the reactor, which can be operated in both downflow and upflow modes and is preferably operated in an upflow mode. Said gases can be fed to different sections of the reactor.

The distillation step is preferably carried out under reduced pressure in the range of 0.0001-0.5 MPa, more preferably 0.001-0.3 MPa.

The hydroprocessing step may consist of one or more reactors operating within the conditions specified above. Part of the distillate produced in the first reactor can be recycled to subsequent reactors.

The deasphalting step by means of hydrocarbon or non-hydrocarbon (eg C ₃ -C ₆ paraffin or isoparaffin) solvent extraction is usually carried out at a temperature in the range of 40-200° C. and a pressure in the range of 0.1-7 MPa. It can also consist of one or more sections operating with the same or different solvents. The solvent recovery step can be carried out in one or more steps under subcritical or supercritical conditions, which enables further fractionation of deasphalted oil (DAO) and resin.

The deasphalted oil (DAO) containing stream can optionally be blended with distillate oils as such and used as synthetic crude oil (syn-oil), or as feedstock for fluid catalytic cracking or hydrocracking processes.

Preferably, depending on the characteristics of the crude oil (metal content, sulfur and nitrogen content, carbonaceous residues), by sending the heavy residue either to the deasphalting unit or to the hydrotreatment unit or to both units To change the feeding method of the whole process, adjust:

· The ratio between the heavy residue (fresh feedstock) sent to the hydrotreatment section and the heavy residue to be sent to deasphalting, said ratio is preferably 0.01-100, more preferably 0.1-10, even more preferably 1-5;

· The circulation ratio between the fresh raw material and tar sent to the deasphalting section, said ratio preferably varies between 0.01-100, more preferably 0.1-10;

· the recycle ratio of fresh feedstock to asphaltenes fed to the hydrotreatment section, said ratio being variable according to variations of these ratios mentioned above;

• The recycle ratio of tars and asphaltenes fed to the hydrotreatment section, which ratio can be varied according to variations of the aforementioned ratios.

This flexibility is particularly useful for fully exploiting the complementary characteristics of the deasphalting unit (reduction of dispersed nitrogen and removal of aromatics) and the hydrogenation unit (high removal of metals and sulfur).

Depending on the type of crude oil, the stability of the stream under study and the quality of the product obtained (also related to the specific downstream processing steps), the fraction of fresh feedstock fed to the deasphalting and hydrotreatment stages can be optimally adjusted.

When the heavy fraction (distillation bottoms) of the complex hydrocarbon mixture produced by the process is used as feedstock to a catalytic cracking unit carrying out simultaneous hydrocracking (HC) and fluid catalytic cracking (FCC), said application Especially applicable.

The combination of catalytic hydrogenation unit (HT) and extraction process (SDA) enables the production of deasphalted oil with low content of impurities (metals, sulphur, nitrogen, carbonaceous residues) and thus easier to process in catalytic cracking process deal with.

A preferred embodiment of the invention is presented below with the aid of the accompanying drawing 1, which should in no way be considered as limiting the scope of the invention itself.

A feedstock (1), preferably slurried in a hydrocarbon matrix, consisting essentially of coal, a suitable solvent (2) and a suitable hydrogenation catalyst (3) is fed to a feedstock containing hydrogen or hydrogen with _H2S (4 ) of the direct coal liquefaction unit (CL), from which the stream (5) leaving the unit is processed through a flash unit (F) in order to obtain a gaseous stream (6) and a carbonaceous liquid stream (7).

The carbonaceous liquid stream (7) is passed to the solvent extraction unit (SDAsh), resulting in an insoluble stream (8) consisting of the mineral matter present in the raw material and unreacted coal and a stream consisting of the resulting liquefied coal and the solvent used A liquid stream (9), the latter stream (9) is then sent to a distillation step (RS) in order to separate the solvent (10) contained therein from another liquid stream (11), the solvent ( 10) Recycle back to the extraction unit, (SDAsh).

A further stream (12) can optionally be separated off as a fraction which can be fed (13) to the light fraction separated off in the distillation or flash unit (D) or recycled (14) as solvent to the liquefaction unit (CL ).

A liquid stream (11) consisting of liquefied coal is mixed with a suitable hydrogenation catalyst (15) and sent together to a hydroprocessing unit (HT) which introduces hydrogen or hydrogen and _H2S (16), from which hydrogenated The stream (17) of hydrogen product and dispersed phase catalyst enters distillation column (D) for fractional distillation, and the light fraction (18) together with distillable products (19), (20) and (21) are mixed with dispersed phase The distillation residue (22) of catalyst and coke is separated.

Said distillation residue (22), the so-called tars, is fed to a deasphalting unit (SDA), whereby two streams are obtained: one (23) consists of deasphalted oil (DAO) and the other (24 ) consists of asphaltenes, the latter being partly or fully added (25) to the liquid stream (11) consisting of liquefied coal and optionally partly recycled (26) to the feedstock (1) consisting essentially of coal.

In order to better illustrate the present invention, some examples are provided below, but should not be considered as limiting the scope of the present invention itself.

Example 1

The following examples were carried out according to the flowchart shown in FIG. 1 .

Liquefaction step

• Reactor: 30cc, steel, equipped with a capillary agitation system and refillable with hydrogen.

Raw material: 5.0 g Columbian E1 Cerrejon coal (Table 1);

Solvent: 5.0 g of hydrotreated DAO;

Catalyst: 200ppm of Mo (introduced as a water-soluble precursor)

·Temperature: 400℃;

·Stay time: 2 hours

·Pressure: 15MPa.

The coal liquefaction step is carried out under the operating conditions indicated above. After the test was completed, the reactants were quenched, the autoclave was depressurized, and the gas was collected into a sample bag for gas chromatographic analysis. The non-gaseous products present in the reactor were recovered with THF and filtered on a 0.5 μm Teflon filter to remove THF-insoluble components composed of inorganic matter (ash), unreacted organic fractions and catalysts.

Calculate the conversion rate as follows:

Conversion rate=(coal _maf -IOM)/(coal _maf )×100

In the formulas given above, the coal weight is measured on a maf (moisture and ash free) basis, ie the total weight of coal minus the ash and water fractions. IOM (Insoluble Organic Matter) refers to the THF insoluble product recovered at the end of the reaction, from which ash and water have been subtracted.

Hydroprocessing steps for liquids from coal:

• Reactor: 30cc, steel, equipped with a capillary agitation system and refillable with hydrogen.

Feedstock: 10 g of liquid from coal produced in the liquefaction step;

Catalyst: 3000ppm of Mo (introduced as a water-soluble precursor);

·Temperature: 415°C;

·Stay time: 4 hours

·Pressure: 16MPa.

After the test was completed, the reactants were quenched, the autoclave was depressurized, and the gas was collected into a sample bag for gas chromatographic analysis. The non-gaseous products present in the reactor were recovered with THF and filtered on a 0.5 μm Teflon filter to separate the THF insoluble components composed of catalyst, metal sulfide and possible coke. The THF insoluble fraction was then treated with excess n-pentane to precipitate _C5 asphaltenes and generate DAO (deasphalted oil), which was analyzed by GC SIM-DIST to detect the following fractions or determine the yield:

- Naphtha (PI-170°C)

-Atmospheric pressure gas oil (170-350℃)

-Vacuum gas oil (350-500℃)

-Vacuum residue (500℃+)

test results

The results related to the liquefaction step and the subsequent hydrotreating step are listed in Table 2.

Table 1 Characteristics of coal

coal Moisture (w%) Volatile matter (w%) Ash (w%) C(w%) H(w%) N(w%) S(w%) E1CerrejonColumbia 5.25 35.46 4.71 73.7 5.35 1.41 0.61

Table 2 Liquefaction and hydrotreating test results

test Conversion rate (w%) THFI(w%) ASFC₅(w%) C₁-C₄(w%) C₅-170℃(w%) 170-350℃(w%) 350-500℃(w%) 500℃+(w%) Liquefaction step 81 8.7 37.9 1.4 - - - - Hydrotreating step - 1.0 4.1 2.6 0.2 10.2 27.0 40.5

Example 2

Using the same method as described in Example 1, 5.0 g of coal was treated with 5.0 g of DAO solvent in the presence of a solid mixture containing molybdenum sulfide, metal sulfide and heavy carbonaceous species. The above mixture is from a heavy hydrocarbon feedstock hydroprocessing test and represents the bottom of a partial deasphalting column (the "flush" stream of Figure 1), the amount of solid mixture introduced into the reactor was such that the concentration of molybdenum was equal to 200 ppm.

Table 3 shows the relevant data of the coal liquefaction test.

Table 3: Liquefaction test results

test Conversion rate (w%) THFI(w%) ASFC₅(w%) C₁-C₄(w%) Liquefaction step 79 10.6 38.2 1.5

Example 3

Carry out the following experiments according to the flowchart shown in Figure 1.

Liquefaction step

• Reactor: 3000cc, steel, equipped with a magnetic stirring system and refillable with hydrogen.

Raw material: 250g coal (Table 1);

Solvent: 250g LCO (light cycle oil);

Catalyst: 500ppm of Mo (introduced as a water-soluble precursor)

·Temperature: 415°C;

·Stay time: 4 hours

·Pressure: 16MPa.

After the test was completed, the reactants were quenched, the autoclave was depressurized, and the gas was collected into a sample bag for gas chromatographic analysis.

The product was recovered from the reactor and filtered to separate the THF insoluble fraction consisting of inorganics (ash) from unreacted organic fractions and catalyst.

The liquefaction step was repeated several times to obtain sufficient liquid for subsequent hydrogenation experiments.

See the data shown in Tables 2 and 3 for coal conversion results.

flash step

The light fraction (350° C.-) consisting of the solvent used in the liquefaction step and the distillate produced by the reaction was separated by batch distillation.

Hydrotreating step

The product (column bottom, 350°C+residue) obtained in the flashing step was used for hydrotreating reaction under the conditions specified in Example 1.

Gaseous products are separated at the end of the hydrogenation step. The product is then deasphalted with liquid propane. The resulting _C3DAO is then separated and recovered. Eight hydroprocessing trials were performed sequentially, each trial using a feedstock consisting of 350 °C+ residue from the coal liquefaction process and catalyst-containing _C3 The catalyst added in one experiment was completely recycled. A certain amount of residual oil from coal liquid should be added in each step, so that the continuous operation can be carried out on the basis of the same total amount of raw materials (about 300g).

Under these operating conditions, the ratio between the amount of coal liquids and the amount of recycled products reaches 1:1.

The relevant data (% by weight relative to the amount of liquid feedstock introduced) for the discharge stream after the last cycle are given below:

Gas: 7%

Naphtha (C ₅ -170°C): 8%

Atmospheric gas oil (AGO, 170-350°C): 19%

·Deasphalted oil (VGO+DAO): 66%

In the above examples, no flushing step of the recycle stream is required.

Claims (52)

1. one kind contains the integral method that the coal feedstock conversion is a product liquid, following at least seven technique units of this method coupling: unit (D), solvent deasphalting unit (SDA) of catalyst hydrogenation conversion unit (HT), distillation or the flash distillation hydrogenation unit products therefrom of the unit (SDAsh) that the unit (F) of gelatin liquefaction unit (CL), distillation or flash distillation liquefaction unit products therefrom, solvent extraction remove ash content, the unit (RS) that fractionation by distillation goes out solvent, slurry phase

It is characterized in that comprising the steps:

In the presence of suitable hydrogenation catalyst, will contain the coal raw material and send into one or more direct gelatin liquefaction step (CL);

One or more distillation or flash distillation step (F) are sent in the materials flow that will contain gelatin liquefaction reaction products therefrom, obtain gaseous stream and liquid stream;

Liquid stream is sent into solvent extraction (SDAsh), thereby obtain insoluble materials flow and one liquid stream of forming by gained liquefaction coal and solvent for use that one is made up of mineral substance that exists in the raw material and unconverted coal;

To send into one or more distilation steps by the liquid stream that gained liquefaction coal and solvent for use are formed, and, make its recirculation return solvent extraction (SDAsh) so that contained solvent in the liquid stream is separated substantially;

With the materials flow substantially formed by liquefaction coal and to the small part diasphaltene unit the asphaltenes materials flow of gained mix with suitable hydrogenation catalyst, and the mixture that obtains delivered to introduced hydrogen or hydrogen and H ₂The hydrotreating reactor of S mixture (HT);

One or more distillation or flash distillation step (D) are sent in the materials flow that will contain hydrotreatment reaction product and disperse phase catalyzer, thereby will separate from the different fractions of hydrotreatment reaction;

With at least a portion leave flash evaporation unit contain rich metallic sulfide that disperse phase catalyzer, raw material demetalization process generate and the distillation residue of optional coke is that tar or liquid are sent into the diasphaltene district (SDA) that has solvent, the liquid stream that optional at least a portion is made up of liquefaction coal substantially is also as charging, thereby obtain two bursts of materials flows, another strand is made of bituminous matter by deasphalted oil (DAO) formation for one.

2. by the process of claim 1 wherein that containing the coal raw material is made up of coal substantially.

3. by the process of claim 1 wherein that the middle suitable hydrogenation catalyst that exists of liquefaction step (CL) to small part can reclaim from the downstream units of described step.

4. by the method for claim 2, wherein the raw material of being made up of coal is substantially made slurry in hydrocarbon substrate.

5. by the method for claim 4, wherein hydrocarbon substrate is from the downstream units of liquefaction step (CL).

6. by the method for claim 5, wherein hydrocarbon substrate is the part of the materials flow of being made up of deasphalted oil (DAO) that obtains of the part of materials flow of the asphaltenes that obtains of diasphaltene unit (SDA) and the used dispersed catalyst of hydrotreating step (HT) and/or diasphaltene step (SDA).

7. press the method for claim 1, wherein by containing coal charge stream and aromatic solvent and the suitable disperse phase catalyst mix of amount for 20-80% scope coal amount, at the hydrogen pressure of the temperature of 360-440 ℃ of scope, 3-30MPa be less than or equal and operate under the residence time condition of 4h, carry out direct liquefaction to containing coal charge stream.

8. to send into the containing in the coal raw material of liquefaction unit (CL) by the process of claim 1 wherein that the part of materials flow of asphaltenes that diasphaltene unit (SDA) obtained and hydrotreating step (HT) catalyst system therefor joins as solvent.

9. to send into the containing in the coal raw material of liquefaction unit (CL) by the process of claim 1 wherein that the part of the materials flow of being made up of deasphalted oil (DAO) that diasphaltene step (SDA) is obtained joins as solvent.

By the process of claim 1 wherein with a part from distillation or flash evaporation unit (D) obtain matter and heavy ends promptly in matter and heavy distilled oil join as solvent and will send into the containing in the coal raw material of liquefaction unit (CL).

11. will send into the containing in the coal raw material of liquefaction unit (CL) by the process of claim 1 wherein the isolated solvent of a part of distilation steps (RS) joined as solvent.

12. by the process of claim 1 wherein that other isolates one materials flow as cut in the distilation steps (RS) of the liquid stream that liquefaction coal and solvent for use are formed.

13., wherein a part is joined as solvent as isolated another burst materials flow of cut from distilation steps (RS) and will send into the containing in the coal raw material of liquefaction unit (CL) by the method for claim 12.

14. method by claim 1, wherein by described materials flow and amount are 20-80% scope coal amount aromatic solvent and suitable disperse phase catalyst mix, at the hydrogen pressure of the temperature of 360-440 ℃ of scope, 3-30MPa be less than or equal and operate under the residence time condition of 4h, carry out direct liquefaction to containing coal charge stream.

15. by the process of claim 1 wherein the solvent extraction that removes ash content in the presence of suitable aromatic solvent, under the temperature of 150-350 ℃ of scope and the atmospheric condition of 20-60 scope, implement.

16. join in the raw material of forming by coal that to send into liquefaction unit (CL) being selected from heavy crude, distillation residue, heavy oil, thermal tar, oil sands bitumen, various coal and some other heavy feed stock that is called the hydrocarbon source high boiling point raw material of dirty oil from the catalytic treatment process by the process of claim 1 wherein.

17. join in the liquid stream that the liquefaction coal that will send into hydrotreating step (HT) forms being selected from heavy crude, distillation residue, heavy oil, thermal tar, oil sands bitumen, various coal and some other heavy feed stock that is called the hydrocarbon source high boiling point raw material of dirty oil from the catalytic treatment process by the process of claim 1 wherein.

18. method by claim 1, the materials flow that wherein contains hydrotreatment reaction product and disperse phase catalyzer is being admitted to one or more distillation or flash distillation step (D) before, will be through the pre-step process of the separation of a high top pressure operation, obtain one light ends and one heavy ends, only described heavy ends is sent into described distilation steps (D).

19. by the method for claim 18, the light ends that its mesohigh separating step obtains can be delivered to the second aftertreatment hydrogenation section, generates one and contains C ₁-C ₄Gas and H ₂The lighter fraction of S and one contain the petroleum naphtha of hydrotreatment and gas oil than last running.

20. by the method for claim 19, wherein aftertreatment hydrogenation reaction is to carry out under the pressure of 7-14MPa scope.

21. method by claim 1, wherein all are mixed with the hydrogenation catalyst that is fit to by the liquid stream that liquefaction coal is formed substantially, send into hydrotreating reactor (HT) then, and asphaltenes that will at least 60% and also contain the disperse phase catalyzer and possible coke and the materials flow of being rich in from the metal of initial feed are recycled to the hydrotreatment district.

22. by the method for claim 21, wherein at least 80% asphaltenes materials flow is recycled to the hydrotreatment district.

23. method by claim 1, the liquid stream of wherein will be substantially being made up of liquefaction coal and most at least asphaltenes and also contain the disperse phase catalyzer and the materials flow of possible coke mixes with suitable hydrogenation catalyst are sent into hydrotreating reactor (HT) then.

24. by the process of claim 1 wherein that distillation residue (tar) or liquid that a part is left flash evaporation unit (D) delivers to diasphaltene section (SDA), and the described distillation of at least a portion residual content or flash distillation residual oil are admitted to hydrotreating reactor.

25. by the method for claim 24, wherein the described distillation of at least a portion residual content or flash distillation residual oil (D) are sent into hydrotreating reactor with at least a portion from the asphaltenes materials flow of diasphaltene section (SDA).

26. by the process of claim 1 wherein that the distillation residue of at least 80 weight % is sent to diasphaltene district (SDA).

27. by the method for claim 26, wherein the distillation residue of at least 95 weight % is sent to diasphaltene district (SDA).

28. by the process of claim 1 wherein that the residual content distillation residue that at least a portion is not delivered to the diasphaltene district is that tar is recycled to hydrotreatment section (HT).

29. by the process of claim 1 wherein that distilation steps carries out under the reduced pressure of 0.0001-0.5MPa scope.

30. by the method for claim 29, wherein distilation steps carries out under the reduced pressure of 0.001-0.3MPa scope.

31. by the process of claim 1 wherein that hydrotreating step carries out under the pressure of the temperature of 370-480 ℃ of scope and 3-30MPa scope.

32. by the method for claim 31, wherein hydrotreating step carries out under the pressure of the temperature of 380-440 ℃ of scope and 10-20MPa scope.

33. by the process of claim 1 wherein that the diasphaltene step is to carry out under 40-200 ℃ of range temperature and 0.1-7MPa scope pressure.

34. by the process of claim 1 wherein that deasphalting solvent is the light paraffins of 3-7 carbon atom.

35. by the process of claim 1 wherein that diasphaltene step (SDA) step is to divide a step or multistep to carry out under subcritical or super critical condition.

36. by the process of claim 1 wherein the materials flow fractionation that to adopt conventional distillation technique that deasphalted oil (DAO) is formed.

37. isolate also the materials flow that deasphalted oil (DAO) is formed condensed product mix with distilation steps by the process of claim 1 wherein.

38. by the process of claim 1 wherein that but hydrogenation catalyst is derived from decomposition of precursors or premolding compound based on a kind of or various transition metal.

39. by the method for claim 37, wherein transition metal is a molybdenum.

40. by the metal or the multiple concentration of metal that the process of claim 1 wherein to exist in the hydroconversion reactions device, the catalyst concn scope is 300-20000ppm.

41. by the method for claim 40, metal or multiple concentration of metal wherein to exist in the hydroconversion reactions device, the catalyst concn scope is 1000-10000ppm.

42. by the process of claim 1 wherein, product is separated into solid ingredient and liquid ingredient, from liquid ingredient, separates described solvent subsequently with being called the processing section that suitable solvent is delivered in the asphaltenes materials flow of washing materials flow from diasphaltene section (SDA).

43. by the method for claim 42, the amount of wherein washing materials flow is the 0.5-10 volume % of fresh feed.

44., send into the oil fuel cut after wherein at least a portion being derived from the liquid distillate former state of flushing materials flow processing section or isolating solvent and/or after adding suitable diluent by the method for claim 43.

45. by the method for claim 44, wherein at least a portion liquid distillate of deriving from flushing materials flow processing section is recycled to the liquid distillate that hydrotreating reactor and/or at least a portion derive from flushing materials flow processing section and is recycled to gelatin liquefaction unit (CL)

46. by the method for claim 42, wherein washing materials flow processing section solvent for use is the gas oil mixture that maybe can obtain from the refinery that aromatic solvent or this method itself are produced.

47. by the method for claim 46, wherein aromatic solvent is toluene and/or is xylene mixture.

48. by the method for claim 40, volume ratio from 1 to 10 change of wherein solvent/flushing materials flow.

49. by the method for claim 48, volume ratio from 1 to 5 change of wherein solvent/flushing materials flow.

50. by the method for claim 49, volume ratio from 1.5 to 3.5 changes of wherein solvent/flushing materials flow.

51., wherein the solid ingredient of processing product is delivered to another and is used for the treatment step of the contained transition metal of selective recovery hydrogenation catalyst by claim 42 and 38 method.

52. the method by claim 51 wherein is recycled to the transition metal that is reclaimed hydrotreating reactor (HT).

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