EP3562916A1

EP3562916A1 - Process for producing middle distillates

Info

Publication number: EP3562916A1
Application number: EP17821941.6A
Authority: EP
Inventors: Ariel Bru; Nicolaas Van Dijk; Bastiaan Willem Van Hasselt; Eduardus Theodorus Cornelis BINNEVELD; Eduard Meijer; Hendrik Stichter
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 2016-12-28
Filing date: 2017-12-27
Publication date: 2019-11-06
Also published as: WO2018122274A1; CN110114445A

Abstract

The invention provides a process for producing middle distillates from a residual hydrocarbonaceous feedstock, comprising the steps of: (a) thermally cracking the residual hydrocarbonaceous feedstock in a first thermal cracking unit to obtain a thermally cracked product comprising a thermally cracked residue; (b) deasphalting at least the thermally cracked residue to obtain a thermally cracked deasphalted oil and an asphaltic product; (c) thermally cracking at least part of the thermally cracked deasphalted oil in a second thermal cracking unit to obtain a twice thermally cracked deasphalted oil; (d) hydrocracking at least part of the twice thermally cracked deasphalted oil as obtained in step (c) to obtain a hydrocracked product; and (e) subjecting at least part of the hydrocracked product as obtained in step (d) to a separation treatment to obtain at least a middle distillate fraction. The invention further provides a process for producing ultra-low sulphur fuel oil and middle distillates and a low-sulphur fuel oil or fuel oil blending component having a sulphur content in the range of from 0.03%wt. to less than 0.5%wt.

Description

PROCESS FOR PRODUCING MIDDLE DISTILLATES

Field of the Invention

The present invention relates to process for producing middle distillates. The present invention further relates to a process for producing a fuel oil that meets the maximum sulphur specification in force as of 1^st January 2020, as set by the International Maritime Organisation. The present invention further relates to a low sulphur fuel oil or fuel oil blending component .

Background of the Invention

In view of new emission standards much research and development is nowadays directed to the production of so- called ultra-low sulphur middle distillates such as ultra-low sulphur diesel fuels.

Many multi-step processes are known for the

production of ultra-low sulphur middle distillates.

Refineries face the challenge of processing multiple crude oils and crude oil blends of varying compositions and processing challenges into products that have to meet ever more stringent specifications .

With the recent tightening of maximum sulphur specifications in force as of 1^st January 2020, as set by the International Maritime Organisation, refineries producing fuel oil that does not meet the sulphur specification, are confronted with the challenge of efficiently converting its refinery operations to one capable of producing ultra-low sulphur middle distillates in high yield and/or fuel oil meeting the required sulphur specification.

WO2015/097199 describes a process for producing ultra-low sulphur middle distillates in high yield using a hydrodemetallisation unit. Not many refineries have substantial hydrodemetallisation units and, in the absence of very substantial capital investment, not a practical solution for those refineries.

EP0372652 describes a process for the conversion of a heavy hydrocarbonaceous feedstock in a two-step process of thermal cracking of a short residue and solvent deasphalting of the thermally cracked residue to prepare a deasphalted oil. EP0372652 is silent about sulphur content or metal content and does not describe a process for producing ultra-low sulphur middle distillates or ultra-low sulphur fuel oil. Page 4, lines 25-26 describe that the deasphalted oil can be used as feed for a hydrotreatment or a hydrocracking process, for a

catalytic cracking process or for a thermal cracking process, but the specific multi-step process of the present invention has not been described.

Summary of the invention

It is an aim to provide a process for producing ultra low sulphur middle distillates in high yields. It is a further aim to provide a process for producing a fuel oil that meets the maximum sulphur specification in force as of 1^st January 2020, as set by the International Maritime Organisation. It is further an aim to provide a low sulphur fuel oil or fuel oil blending component.

In one aspect, the present invention provides a process for producing middle distillates from a residual hydrocarbonaceous feedstock, comprising the steps of: (a) thermally cracking the residual hydrocarbonaceous feedstock in a first thermal cracking unit to obtain a thermally cracked product comprising a thermally cracked residue ; (b) deasphalting at least the thermally cracked residue to obtain a thermally cracked deasphalted oil and an asphaltic product;

(c) thermally cracking at least part of the thermally cracked deasphalted oil in a second thermal cracking unit to obtain a twice thermally cracked deasphalted oil;

(d) hydrocracking at least part of the twice thermally cracked deasphalted oil as obtained in step (c) to obtain a hydrocracked product; and

(e) subjecting at least part of the hydrocracked product as obtained in step (d) to a separation treatment to obtain at least a middle distillate fraction.

In accordance with the present invention high yields of middle distillates containing a small amount of sulphur, preferably less than 10 ppmw sulphur, can advantageously be produced from residual

hydrocarbonaceous feedstocks .

In another aspect, the present invention provides a process for producing ultra-low sulphur fuel oil and middle distillates from a residual hydrocarbonaceous feedstock, comprising the steps of:

(a) thermally cracking the residual hydrocarbonaceous feedstock in a first thermal cracking unit to obtain a thermally cracked product comprising a thermally cracked residue;

(b) deasphalting at least the thermally cracked residue to obtain a thermally cracked deasphalted oil and an asphaltic product;

(c) thermally cracking at least part of the thermally cracked deasphalted oil in a second thermal cracking unit to obtain a twice thermally cracked deasphalted oil; (d) hydrocracking at least part of the twice thermally cracked deasphalted oil as obtained in step (c) to obtain a hydrocracked product;

(e) subjecting at least part of the hydrocracked product as obtained in step (d) to a separation treatment to obtain at least a middle distillate fraction, and a fraction boiling in the fuel oil range;

(f) optionally subjecting at least part of the fraction boiling in the fuel oil range to a further hydrocracking step to produce a hydrocracked product (f) ; and

(g) subjecting at least part of the hydrocracked product as obtained in step (f) to a separation treatment to obtain at least a middle distillate fraction and a fraction boiling in the fuel oil range.

In yet another aspect, the present invention provides a low-sulphur fuel oil or fuel oil blending component having a sulphur content in the range of from 0.03%wt. to less than 0.5%wt., comprising 50-95% wt . of a fraction boiling in the fuel oil range obtainable from step (e) or (g) of the process as described above and 5-

50%wt. of a fraction boiling in the fuel oil range having a sulphur content of more than 0.5%wt.

Brief Description of the Drawings

The drawing figure depicts one or more

implementations in accordance with the present teachings, by way of example only, not by way of limitation. In the figure, like reference numerals refer to the same or similar elements.

Figure 1 depicts a preferred embodiment of the process for producing middle distillates according to the present invention.

Detailed description of the invention The residual hydrocarbonaceous feedstocks to be used in accordance with the present invention may be residual hydrocarbon oils, such as those obtained as residue in the distillation of crude oils at atmospheric or reduced pressure, commonly referred to as atmospheric (or long) residue and vacuum (or short) residue respectively.

Preferably, the residual hydrocarbonaceous feedstock is a vacuum residue. Typically, at least 55 wt%, preferably at least 75 wt%, more preferably at least 85 wt%, and even more preferably at least 90 wt% of the residual

hydrocarbonaceous feedstock has a boiling point at atmospheric pressure of above 550 °C.

Step (a) comprises thermally cracking the residual hydrocarbonaceous feedstock in a first thermal cracking unit to obtain a thermally cracked product comprising a thermally cracked residue.

Typically, the residual hydrocarbonaceous feedstock is preheated, usually in one or more furnaces or furnace sections provided with heat exchange tubes or coils through which the feedstock is passed. The feedstock is preferably pre-heated to a temperature in the range of from 350 - 600 °C and fed to a thermal cracking zone.

In the thermal cracking zone the thermal cracking takes place. The feedstock may be passed in an upward or a downward direction through the cracking zone.

Preferably, the flow is upward. The feedstock may be passed through a cracking zone that is constituted as an empty vessel, e.g. as described in US-A 1,899,889.

Preferably the thermal cracking zone is situated in a soaking vessel containing internals. The internals are preferably in the form of perforated plates. In such a soaking vessel the internals provide compartments by means of which the occurrence of back-mixing is decreased. An example of a soaking vessel is described in EP-A 7656.

In one embodiment of the invention, preferably, the effluent is flashed or fractionated to yield a thermally cracked distillate fraction, or fractions, and a

thermally cracked residue.

In a preferred aspect of the invention, in the thermal cracking step (a) the thermally cracked product is separated into a thermally cracked residue and one or more thermally cracked distillates.

Preferably, the thermal cracking step (a) is operated at a conversion in the range of from 25 to 55%wt, more preferably in the range of from 30 to 50 %wt .

The thermal cracking is generally carried out in the absence of reducing gases, such as hydrogen. The cracking can be carried out in the presence of steam. The

conditions at which the thermal cracking may be carried out can be varied. One might adjust the temperature, pressure and residence time at will in such a way that the desired conversion occurs. It will be evident to a person skilled in the art that the same conversion can be obtained at a high temperature and a short residence time on the one hand and at a lower temperature but at a longer residence time at the other hand. Further, the cracking reactions are endothermic and therefore the temperature tends to decrease over the cracking zone in the case of soaker cracking. Hence, the person skilled in the art will be able to select the conditions in the cracking zone such that the desired conversion level will be obtained. Suitable cracking conditions include a temperature of 350 to 600 °C, a pressure of 1 to 100 bar abs . and a residence time of 0.5 to 60 min. The residence time relates to the cold feedstock. In step (b) , at least the thermally cracked residue is deasphalted to obtain a thermally cracked deasphalted oil of which at least 45 wt% , preferably at least 65 wt%, more preferably at least 80 wt%, and even more preferably at least 85 wt% has a boiling point above 550

°C and an asphaltic product.

The deasphalting in step (b) may be carried out in any conventional manner. A well-known and suitable deasphalting method is solvent deasphalting. In

accordance with the present invention the deasphalting in step (b) is preferably carried out by means of a solvent deasphalting treatment. More preferably, step (b) is carried out by means of a solvent deasphalting treatment and is operated at an extraction depth in the range of from 25 to 65%wt.

According to one embodiment the thermally cracked product of step (a) is passed without separate

distillation or (vacuum) flash step to step (b) .

According to another embodiment the thermally cracked product of step (a) is flashed or fractionated such that only gases, or gases and a naphtha fraction (i.e. 95%wt. boiling up to 160°C) or gases, a naphtha fraction and a gasoil fraction (i.e. 95%wt. boiling up to 350 °C) are removed from the thermally cracked product and a thermally cracked residue is formed containing a relatively high amount of lighter oil components.

It will be appreciated that higher levels of extraction depth are more easily achieved when a

thermally cracked product or a thermally cracked residue having a relatively high amount of lighter oil components is passed to a solvent deasphalting step.

According to one preferred embodiment, the amount of the thermally cracked residue having a boiling point at or below 520 °C is 10%wt. or less, more preferably less than 9%wt . even more preferably less than 5%wt.

In the embodiment where the amount of the thermally cracked residue having a boiling point at or below 520 °C is 10%wt. or less, more preferably less than 9%wt . , even more preferably less than 5%wt., the extraction depth is preferably from 30 to 60%wt, even more preferably from 35 to 55%wt.

In solvent deasphalting the hydrocarbon feed is typically treated counter-currently with an extracting medium which is usually a light hydrocarbon solvent containing paraffinic compounds. Commonly applied paraffinic compounds include C3-8 paraffinic

hydrocarbons, such as propane, butane, isobutane, pentane, isopentane, hexane or mixtures of two or more of these. For the purpose of the present invention, it is preferred that C3-C5 paraffinic hydrocarbons, most preferably butane, pentane or a mixture thereof, are used as the extracting solvent. In general, the extraction depth increases at increasing number of carbon atoms of the extracting solvent. In this connection it is noted that the higher the extraction depth, the larger the amount of hydrocarbons being extracted from the

feedstock, the smaller and more viscous the asphaltic product will be, the heavier the asphaltenes will be in the asphaltic product to be obtained in step (b) .

In a solvent deasphalting treatment, typically, a rotating disc contactor, empty column or a plate column may be used with the feedstock entering at the top and the extracting solvent entering at the bottom. The lighter and/or paraffinic hydrocarbons which are present in the feedstock typically dissolve in the extracting solvent and are withdrawn as the thermally cracked deasphalted oil at the top of the apparatus . The

asphaltenes which are insoluble in the extracting solvent are withdrawn in the form of the asphaltic product at the bottom of the apparatus . The conditions under which deasphalting takes place are known in the art. Suitably, deasphalting is carried out at a total extracting solvent to residual hydrocarbon oil ratio of 1.5 to 8 wt/wt, a pressure of from 1 to 60 bara and a temperature of from 40 to 200 ° C.

The asphaltic product withdrawn from the

deasphalting step can be used for any use known in the art, such as for fuel oil, bitumen, gasifier feed or power station feed. It will be appreciated that the asphaltic product will not meet the recently adopted stringent maximum sulphur specifications for fuel oil but will have a sulphur content of more than 0.5%wt., typically at least 2%wt., such as from 2.5 %wt . to 7% wt .

If desired, at least part of the asphaltic product can be used as a fraction boiling in the fuel oil range having a sulphur content of more than 0.5%wt in the low- sulphur fuel oil or fuel oil blending component of the present invention.

As used herein, a fraction boiling in the fuel oil range is typically a residual fraction boiling above 370 °C (5%wt point, i.e. 95%wt. boiling above 370 °C) .

According to a preferred embodiment at least part of the asphaltic product as obtained in step (b) is

subjected to a gasification step (h) to obtain hydrogen and carbon monoxide .

It will be appreciated that if the asphaltic product is used in a further process step, in practice in a refinery, the extraction depth of the solvent

deasphalting step may be limited by the maximum viscosity that the subsequent process unit as installed in the refinery can handle.

A deasphalting treatment generally causes a

substantial amount of the metallic contaminants present in the feed as high-molecular weight complexes to accumulate in the asphaltic product rather than in the deasphalted product. Nonetheless, it is understood in the art, such as for example in WO2015/097199, that the metals content of the deasphalted product will be such that the deasphalted product needs to be subjected to a hydrodemetallizing step before it can be subjected to further hydroprocessing upgrading steps.

In accordance with the present invention it has been found that if the deasphalting step is preceded by a first thermal cracking step and followed by a second thermal cracking step, the metals content in at least part of the twice thermally cracked deasphalted oil is sufficiently low so as to allow hydrocracking of the twice thermally cracked deasphalted oil without unduly poisoning the hydrocracking catalyst. If desired, the hydrocracking unit comprises a guard bed or catalyst bed having activity for further hydrodemetallisation, but in general no separate hydrodemetallisation step in a separate unit is needed.

Accordingly, in step (c) , at least part of the thermally cracked deasphalted oil as obtained in step (b) is thermally cracked in a second thermal cracking unit to obtain a twice thermally cracked deasphalted oil.

Preferably, in step (c) the entire thermally cracked deasphalted oil as obtained in step (b) is thermally cracked .

According to a preferred embodiment, the second thermal cracking step (c) is operated at a conversion in - li the range of from 25 to 80%wt, more preferably a

conversion from 30%wt to 75%wt.

The second thermal cracking is generally carried out in the absence of reducing gases, such as hydrogen. The cracking can be carried out in the presence of steam. The conditions at which the thermal cracking may be carried out can be varied. One might adjust the temperature, pressure and residence time at will in such a way that the desired conversion occurs. It will be evident to a person skilled in the art that the same conversion can be obtained at a high temperature and a short residence time on the one hand and at a lower temperature but at a longer residence time at the other hand. Further, the cracking reactions are endothermic and therefore the temperature tends to decrease over the cracking zone in the case of soaker cracking. Hence, the person skilled in the art will be able to select the conditions in the cracking zone such that the desired conversion level will be obtained. Suitable cracking conditions include a temperature of 350 to 600 °C, a pressure of 1 to 100 bar abs . and a residence time of 0.5 to 60 min. The residence time relates to the cold feedstock.

As the thermally cracked deasphalted oil is

relatively clean, but has already been subjected to a first thermal cracking treatment, it has been found that the conditions required to reach a desired conversion level in the second thermal cracking step are typically more severe than the conditions required to reach the same conversion in the first thermal cracking step. For example, if the residence time and pressure is kept constant between the two thermal cracking steps, the second thermal cracking step may typically be carried out at a temperature that is 10°C to 80 °C higher than the temperature used in the first thermal cracking step to reach the same level of conversion.

The thermally cracked deasphalted product which is thermally cracked again in step (c) is a pure and heavy deasphalted product. This means that at least 45 wt%, preferably at least 65 wt%, more preferably at least 80 wt%, and even more preferably at least 85 wt% of the deasphalted product to be treated in step (c) has a boiling point of above 550 °C. Unlike in hydroconversion processes such as for instance disclosed in EP 1731588

Al, the entire undiluted deasphalted product as obtained in step (b) can now be processed in step (c) , and there is no need to dilute the deasphalted product before it can be further processed. One of the advantages of the present invention is the fact that such an undiluted heavy deasphalted product can be further processed, resulting in such a high yield of low sulphur middle distillates .

The twice thermally cracked deasphalted oil will typically comprise light and middle distillates (Naphtha,

Kerosene, Gasoil) , and residual fraction (s), boiling above 370 °C (5%wt point, i.e. 95%wt. boiling above 370 °C) . In addition, it will be appreciated that the thermal cracking step will produce products that are gaseous at ambient temperature and atmospheric pressure.

According to one preferred embodiment, the twice thermally cracked deasphalted oil is separated into one or more fractions boiling below 370 °C (95%wt. point, i.e. maximum 5%wt. boiling above 370 °C) ; one or more fractions boiling in the vacuum gasoil range and a residue (at most 5%wt. boiling below 550 °C) .

The residue (i.e at most 5%wt . boiling below 550 °C) produced in this embodiment can be used for any use known in the art, such as for fuel oil, bitumen, gasifier feed, including a gasification step to obtain hydrogen and carbon monoxide, or power station feed. It will be appreciated that the residue will not meet the recently adopted stringent maximum sulphur specifications for fuel oil but will have a sulphur content of more than 0.5%wt., typically at least 2%wt., such as from 2.5 %wt . to 7% wt .

If desired, at least part of the residue can be used as a fraction boiling in the fuel oil range having a sulphur content of more than 0.5%wt in the low-sulphur fuel oil or fuel oil blending component of the present invention .

In step (d) , at least part of the twice thermally cracked deasphalted oil as obtained in step (c) is hydrocracked to obtain a hydrocracked product.

Preferably, in one embodiment, in step (d) the entire twice thermally cracked deasphalted oil product as obtained in step (c) is hydrocracked. It is however not critical to the invention that the entire twice thermally cracked deasphalted oil product is hydrocracked.

It will be appreciated that it may not be necessary to subject the part of the twice thermally cracked deasphalted oil boiling in the naphtha, kerosene and gasoil range to a hydrocracking step. Instead, it may be sufficient and in fact preferred to subject the part of the twice thermally cracked deasphalted oil boiling below 370 °C (95%wt. point, i.e. maximum 5%wt. boiling above 370 °C) to a hydrotreating step.

Accordingly, in one preferred embodiment, the fraction of the twice thermally cracked deasphalted oil boiling in the vacuum gasoil range and higher (at most 5%wt. boiling below 320°C, preferably at most 5%wt.

boiling below 370 °C) is hydrocracked in step (d) . The metals content in the twice thermally cracked deasphalted oil boiling in the vacuum gasoil range and higher may be sufficiently low so as to allow

hydrocracking of the twice thermally cracked deasphalted oil without unduly poisoning the hydrocracking catalyst.

The level of metals content that is acceptable depends on the hydrocracking catalyst being employed and the metals content in the feed to the process of the invention, which in turn is dependent on the crude diet of the refinery. If desired, the hydrocracking unit comprises a guard bed or catalyst bed having activity for further hydrodemetallisation, but, preferably, no separate hydrodemetallisation step in a separate unit is needed.

It has now surprisingly been found that the twice thermally cracked deasphalted oil boiling in the vacuum gasoil range has a relatively low metal content.

Therefore, according to a particularly preferred

embodiment of the invention, the twice thermally cracked deasphalted oil fraction boiling in the vacuum gasoil range is used as feed to hydrocracking step (d) .

Accordingly, preferably at least 20%wt., more preferably at least 40%wt., even more preferably at least 60%wt., even more preferably at least 80%wt., even more preferably at least 90%wt., even more preferably at least 95%wt., even more preferably the entire twice thermally cracked deasphalted oil fraction boiling in the vacuum gasoil range as obtained in step (c) is hydrocracked.

In this embodiment, the residual fraction of the twice thermally cracked deasphalted oil boiling above the vacuum gasoil range may be used as fuel oil, bitumen, gasifier feed, including a gasification step to obtain hydrogen and carbon monoxide, or power station feed. The residual fraction will normally not meet the recently adopted stringent maximum sulphur specifications for fuel oil but will have a sulphur content of more than 0.5%wt.

If desired, at least part of the residual fraction can be used as a fraction boiling in the fuel oil range having a sulphur content of more than 0.5%wt in the low- sulphur fuel oil or fuel oil blending component of the present invention.

Alternatively, the residual fraction is used as feed to a hydrodemetallisation unit as described in

WO2015/097199.

The hydrocracking in step (d) is preferably carried out in the presence of hydrogen at a temperature in the range of from 300-500 °C and at a pressure in the range of from 80-250 bara.

The hydrocracking in step (d) of the process according to the present invention may be conducted in any way known in the art . The hydrocracking step

typically uses a hydrocracking catalyst. Typically, at least one of the catalysts used in the hydrocracking zone is acidic. Typically, the hydrocracking is carried out in the presence of hydrogen and a hydrocracking catalyst at elevated temperature and pressure. Typically,

hydrocracking catalysts consist of one or more metals from nickel, tungsten, cobalt and molybdenum in

elemental, oxidic or sulphidic form on a carrier such as alumina, silica, silica-alumina or a zeolite. There are many commercially available hydrocracking catalysts which can be applied in the process of the present invention. Preferably, at least one of the catalysts used in the hydrocracking zone is acidic, i.e. contains a silica- alumina and/or zeolitic component as part of the carrier.

The hydrocracking in step (d) may be carried out in a single- or multiple-stage mode of operation. In the case of a single-stage mode of operation, a stacked bed of a hydrodenitrification/first-stage hydrocracking catalyst on top of a conversion catalyst may preferably be used. Particularly preferred

hydrodenitrification/first-stage hydrocracking catalysts are NiMo/A1203 and CoMo/A1203, optionally promoted with phosphorus and/or fluor. Preferred conversion catalysts are those based on NiW/zeolite or NiW/zeolite/silica- alumina. Preferred hydrocracking conditions in step (d) are an operating pressure of 80-250 bara, preferably 90-

220 bara, and a temperature in the range of from 300-500 °C, more preferably 320-460°C, even more preferably 350- 430 °C.

In step (e) , at least part of the hydrocracked product as obtained in step (d) is subjected to a separation treatment to obtain at least a middle

distillate fraction. Preferably, in step (e) the entire hydrocracked product as obtained in step (d) is subjected to the separation treatment.

Typically, in the separation treatment in step (e) also a residual fraction is obtained.

According to one embodiment, preferably, at least part of the residual fraction is recycled to step (d) .

According to one embodiment, preferably at least 20%wt., more preferably at least 40%wt., even more preferably at least 60%wt., even more preferably at least 80%wt., even more preferably at least 90%wt., even more preferably at least 95%wt., is recycled to step (d) .

According to another embodiment, in the separation treatment which is carried out in step (e) also a residual fraction is obtained of which at least part is subjected to a further hydrocracking step (f), and at least part of the hydrocracked product as obtained in step (f) is recycled to step (e) .

According to yet another embodiment, at least part of the hydrocracked product as obtained in step (d) is subjected to a separation treatment to obtain at least a middle distillate fraction and a fraction boiling in the fuel oil range.

The separation treatment in step (e) may typically be a fractionating treatment which is preferably carried out at a temperature in the range from 50 to 400 °C, more preferably at a temperature in the range of from 70 to

370 °C, and preferably a pressure in the range of from

0.03 to 15 bara, more preferably a pressure in the range of from 0.05 to 10 bara.

Preferably, at least 80%wt. of the residual fraction as obtained in the separation treatment in step (e) according to one embodiment of the invention has a boiling point above 370 °C. Preferably, at least 90%wt. of the residual fraction also obtained in the separation treatment in step (e) has a boiling point above 370 °C.

According to another embodiment, at least part of a residual fraction also obtained in step (e) may be recycled to step (a) .

Alternatively, according to another embodiment of the invention, the residual fraction may also be used as a feed for a fluidised bed catalytic cracking (FCC) unit or as a feedstock for lubricating oil manufacture. Of course, a combination of these options is possible as well .

In order to achieve an optimum middle distillates yield, it is preferred that at least a part of the residual fraction obtained in step (e) is again subjected to hydrocracking to improve the yield of middle distillates. Hence, in a preferred embodiment at least part, more preferably 5 to 30 %wt, of a residual fraction which is also obtained in step (e) is recycled to step (d) .

In yet another preferred embodiment, at least part of a residual fraction also obtained in step (e) is subjected to a further hydrocracking step (f), and at least part of the hydrocracked product as obtained in such a step (f) is recycled to step (e) .

Preferably, the hydrocracking in step (d) and/or step (f) is carried out in two or more reaction zones. Preferably, the two or more reaction zones are arranged in a stacked bed configuration.

According to another preferred embodiment, at least part of the residual fraction is subjected to a further hydrocracking step to produce a hydrocracked product (f) ; and at least part of the hydrocracked product as obtained in step (f) is preferably subjected to a separation treatment. The separation may be carried out separately or in the same unit as used for step (e) of the process of the invention. Preferably, the separation step is carried out so as to obtain at least a middle distillate fraction and a fraction boiling in the fuel oil range.

The asphaltic product as obtained in step (b) may be used in several ways. It can for instance be combusted for cogeneration of power and steam. Alternatively, it can be partially combusted for clean fuel gas production, cogeneration of power and steam, hydrogen manufacture or hydrocarbon synthesis. Still another option is

application in bitumen, emulsion fuels or solid fuels by means of pelletizing.

Preferably, at least part of the asphaltic product as obtained in step (b) is subjected to a gasification step (h) to obtain hydrogen and carbon monoxide.

Preferably, such a gasification step (h) is a partial combustion step.

In a preferred embodiment at least part of the hydrogen as obtained in step (h) is recycled to at least one of steps (d) and (f ) .

The middle distillates as obtained in step (e) typically contain less than 10 ppmwt of sulphur.

Preferably, the middle distillates contain less than 8 ppmwt of sulphur, more preferably less than 6 ppmwt of sulphur, and most preferably less than 5 ppmwt of sulphur .

The process of the invention may in one embodiment produce ultra-low sulphur fuel oil and middle distillates from a residual hydrocarbonaceous feedstock, which process comprises the steps of:

(c) thermally cracking at least part of the thermally cracked deasphalted oil in a second thermal cracking unit to obtain a twice thermally cracked product comprising a twice thermally cracked deasphalted oil;

(d) hydrocracking at least part of the twice thermally cracked deasphalted oil as obtained in step (c) to obtain a hydrocracked product;

(e) optionally subjecting at least part of the

hydrocracked product as obtained in step (d) to a separation treatment to obtain at least a middle distillate fraction and a fraction boiling in the fuel oil range;

(f) subjecting at least part of the fraction boiling in the fuel oil range to a further hydrocracking step to produce a hydrocracked product (f ) ; and

It will be appreciated that it is an economic choice for a refiner whether or not to separate out ultra-low sulphur fuel oil in the process of the present invention. A disadvantage of ultra-low sulphur middle distillates is that engines, in particular engines of ships that have been designed to run on fuel oil may need to be adapted to be able to handle ultra-low sulphur middle distillates such as diesel.

Therefore, according to another aspect, the

invention provides a low-sulphur fuel oil or fuel oil blending component having a sulphur content in the range of from 0.03%wt. to less than 0.5%wt., comprising 50-95% wt . of a fraction boiling in the fuel oil range

obtainable from step (e) or (g) of the process as claimed in claim 10 and 5-50%wt. of a fraction boiling in the fuel oil range having a sulphur content of more than

0.5%wt .

In the embodiment of the process of the invention depicted in Figure 1, crude oil or crude oil mix 1 is fractionated in atmospheric distillation unit 20 into multiple distillate products 14 (typically LPG, naphtha and gasoil) and atmospheric residue 2. Atmospheric residue 2 is fractionated in vacuum distillation unit 30 into one or more vacuum distillation products 15

(typically vacuum gasoil) and vacuum residue 3.

Vacuum residue 3 is fed into thermal cracking unit 40 to produce multiple thermally cracked products 16 (typically thermally cracked vacuum gasoil and thermally cracked gasoil and lighter products) and thermally cracked residue 4.

At least a portion of thermally cracked residue 4 is passed via line 6 to solvent deasphalting unit 50.

Optionally a portion of the thermally cracked residue 4 is passed via line 5 to storage and use as fuel oil, bitumen, gasifier feed, including a gasification step to obtain hydrogen and carbon monoxide, or power station feed (not shown) .

In solvent deasphalting unit 50, thermally cracked residue is contacted with propane, iso-butane, butane, pentane, iso-pentane or a mixture thereof as a solvent. The solvent is fed into solvent deasphalting unit 50 via line 19. Thermally cracked deasphalted oil leaves the unit 50 via line 8 and asphaltic product via line 7.

In the unit 50, solvent is mixed with thermally cracked residue and thermally cracked deasphalted oil is extracted from the residue using the solvent. In the unit, solvent is removed from the extract via means not shown and via line 21 and further means not shown recycled to line 19 for re-injection into unit 50.

At least a portion of the thermally cracked

deasphalted oil in line 8 is passed to a second thermal cracking unit 60 via line 9 to produce one or more fractions of twice thermally cracked deasphalted oil. The residual fraction (95%wt. boiling above 550 °C) is passed via line 11 to storage and use as fuel oil, bitumen, gasifier feed, including a gasification step to obtain hydrogen and carbon monoxide, or power station feed (not shown)

Optionally, part of the thermally cracked

deasphalted oil is recycled via line 10 to vacuum distillation unit 30. In an alternative embodiment, optionally part of the thermally cracked deasphalted oil is recycled to thermal cracking unit 40 (not shown) .

According to a preferred embodiment, at least 90% by weight, more preferably at least 95%wt of the thermally cracked deasphalted oil is passed to second thermal cracking unit 60. According to a particular preferred embodiment the recycle of thermally cracked deasphalted oil via line 10 is not employed.

Twice thermally cracked deasphalted oil is typically fractionated into a vacuum gasoil product, a residual fraction and one or more lighter product. At least the twice thermally cracked deasphalted oil boiling in the vacuum gasoil range is fed via line 12 into hydrocracking unit 70 to produce hydrocracked products 17.

Optionally part of the lighter product from unit 60, typically the product boiling in the gasoil range, may be fed with line 12 and lighter product via line 13 to hydrotreating unit 80, producing hydrotreating products 18.

Certain terms used herein are defined as follows:

Conversion is defined as the net "520 °C minus" conversion per pass, calculated as 100% * { [ (wt% boiling at or above 520 °C in feed) - (wt% boiling at or above 520 °C in product)]/ (wt% boiling at or above 520 °C in feed) } . The wt% boiling at or above 520 °C in the feed or the product is determined according to ASTM D2887.

Extraction depth is defined as the yield of extracted "520 °C plus" material calculated as 100% * (wt% boiling at or above 520 °C in extracted product * extracted flow rate [in kg per second])/ (wt% boiling at or above 520 °C in feed * feed flow [in kg per second] ) and is determined according to ASTM D2887.

Vacuum gasoil range is defined as at most 5%wt boiling below 320 °C and at least 90%wt boiling below 550 °C and is determined according to ASTM D2887.

Fuel oil range is defined as a fraction boiling above 370 °C (5%wt point, i.e. 95%wt. boiling above 370 °C) and is determined according to ASTM D2887. A fuel oil range therefore typically comprises a fraction boiling in the vacuum gasoil range and/or a fraction boiling above the vacuum gasoil range .

The present disclosure is not limited to the

embodiments as described above and the appended claims. Many modifications are conceivable and features of respective embodiments may be combined.

Claims

C L A I M S

1. A process for producing middle distillates from a residual hydrocarbonaceous feedstock, comprising the steps of :

(a) thermally cracking the residual hydrocarbonaceous feedstock in a first thermal cracking unit to obtain a thermally cracked product comprising a thermally cracked residue ;

2. A process according to claim 1, wherein the thermal cracking step (a) the thermally cracked product is separated into a thermally cracked residue and one or more thermally cracked distillates.

3. A process according to claim 1 or 2, wherein the thermal cracking step (a) is operated at a conversion in the range of from 25 to 45%wt.

4. A process according to any one of the preceding claims, wherein step (b) is carried out by means of a solvent deasphalting treatment and is operated at an extraction depth in the range of from 25 to 65%wt.

5. A process according to any one of the preceding claims, wherein the second thermal cracking step (c) is operated at a conversion in the range of from 25 to 80%wt .

6. A process according to any one of claims 1 to 5, wherein the hydrocracking in step (d) is carried out in the presence of hydrogen at a temperature in the range of from 300-500 °C and at a pressure in the range of from 80-250 bara.

7. A process according to any one of claims 1 to 6, wherein the twice thermally cracked deasphalted oil fraction boiling in the vacuum gasoil range is used as feed to hydrocracking step (d) .

8. A process according to any one of claims 1 to 6, wherein in the separation treatment which is carried out in step (e) also a residual fraction is obtained of which at least part is recycled to step (d) .

9. A process according to any one of claims 1 to 6, wherein in the separation treatment which is carried out in step (e) also a residual fraction is obtained of which at least part is subjected to a further hydrocracking step (f) , and at least part of the hydrocracked product as obtained in step (f) is recycled to step (e) .

10. A process according to any one of claims 1 to 9, wherein at least part of the asphaltic product as obtained in step (b) is subjected to a gasification step (h) to obtain hydrogen and carbon monoxide.

11. A process for producing ultra-low sulphur fuel oil and middle distillates from a residual hydrocarbonaceous feedstock, comprising the steps of:

(g) subjecting at least part of the hydrocracked product as obtained in step (f) to a separation treatment to obtain at least a middle distillate fraction, and a fraction boiling in the fuel oil range.

12. Low-sulphur fuel oil or fuel oil blending component having a sulphur content in the range of from 0.03%wt. to less than 0.5%wt., comprising 50-95% wt . of a fraction boiling in the fuel oil range obtainable from step (e) or

(g) of the process as claimed in claim 11 and 5-50%wt. of a fraction boiling in the fuel oil range having a sulphur content of more than 0.5%wt.