ES2740837T3 - A procedure to produce oil-based components - Google Patents

Abstract

An oil-based component production process, comprising the steps of: - providing VGO and slack wax; - combine VGO as a main component and slack wax as a minor component to provide a raw material; - subjecting the raw material to a hydrocracking stage to provide a first effluent; - fractionating the first effluent to provide at least a lower fraction and a middle distillate fraction; - recovering the bottom fraction and the middle distillate fraction, where the raw material comprises at most 30% by weight of slack wax and the slack wax is provided as non-purified slack wax obtained from solvent dewaxing of a waxy petroleum feed .

Description

DESCRIPTION

A procedure to produce oil-based components

Field of the Invention

The present invention relates to the field of production of transport fuels and base oil components. More particularly, the invention relates to a process that includes hydrocracking and dewaxing of waxy raw material to produce medium distillate fuel and lubricating base oil.

Background of the invention

Cracking, and especially hydrocracking, is a well-known refinery process used to cleave larger hydrocarbon components into smaller short chain hydrocarbons that can be used as transport fuel components. Cracking is achieved by breaking the carbon-carbon bonds of the C15 to C45 hydrocarbon chain, usually in the presence of a cracking catalyst. The nature of the final products depends on the nature of the feed and the conditions of the process in which the process is carried out, such as temperature, pressure and the nature of the catalyst.

A method widely used to carry out the catalytic cracking of high molecular weight and high boiling hydrocarbon fractions of petroleum crudes is a fluid catalytic cracking (FCC) process, in which a powder catalyst is used. . The catalyst particles are suspended in an upward flow of a heavy diesel feed to form a fluidized bed. Normally, the feed is preheated and then sprayed into the base of the riser through feed nozzles to bring the feed into contact with the hot fluidized catalyst. The temperature of an FCC cracker is normally between 500 ° C and 800 ° C.

Hydrocracking of heavy hydrocarbons can also be achieved in a fixed bed hydrocracker. In this hydrocracker, the raw material is fed down through the catalyst bed together with hydrogen gas. In a fixed bed reactor, the catalyst is fixed on particles, which can be of various sizes and shapes, providing a uniform and homogeneous distribution of the raw material and hydrogen gas and, in addition, maximum contact with the active catalyst. The particles containing the catalyst are fixed in a layer or bed and the raw material and hydrogen gas pass through the layer. Normally, fixed bed reactors contain several layers of catalyst.

A commonly used raw material for hydrocracking is vacuum diesel oil (VGO), which is the heavy oil that remains from petroleum distillation. VGO contains a large amount of cyclic and aromatic compounds, as well as heteroatoms, such as sulfur and nitrogen, and other heavier compounds, depending on the source of crude and the cut of VGO.

The cracking of hydrocarbons is usually accompanied by a hydrogenation process, also called hydrotreatment procedure. The purpose of hydrogenation is to eliminate heteroatoms, such as oxygen, sulfur and / or nitrogen, and also saturate the aromatics normally present in the hydrocarbon feed. The hydrogenation process is normally carried out before the actual hydrocracking process to guarantee the elimination of heteroatoms and the saturation of aromatics. In some cases, hydrogenation also includes ring opening functions. However, there is no substantial cleavage of hydrocarbons in the hydrogenation stage. Prior hydrogenation of the raw material before hydrocracking guarantees a good hydrocracking performance and improves the performance of the products produced in the hydrocracking.

Waxes and slack waxes is a general term for raw material that mainly comprises paraffins. Paraffins in waxes are normally saturated C15-C45 linear hydrocarbons (normal or n-paraffins). Waxes may also contain branched (isomerized or i-paraffins) and cyclic hydrocarbons to some extent. Slack waxes are normally formed by a solvent dewaxing process of a waxy oil feed, such as a VGO stream. The solvent dewaxing process is usually performed by mixing a suitable solvent with the waxy oil feed, then cooling the mixture and separating the waxes as solid wax crystals, for example, by filtration. Waxes can also be produced by the Fischer-Tropsch (F-T) process, in which gas containing carbon monoxide and hydrogen reacts to form a hydrocarbon of various chain lengths. The F-T procedure is widely used in gas-to-liquid (GTL) technologies where natural gas is used as a carbon source. Biomass can also be used as a carbon source in the F-T process and, in general, it is called biomass to liquid technology (BTL). The slack wax produced by dewaxing with solvent contains varied amounts of impurities that make the slack wax a low value product.

A catalytic dewaxing unit (cat. Dewaxing) is a device in which the hydrocarbon feedstock is catalytically dewaxed, that is, it is cracked and selectively isomerized. A dewaxing unit cat. In general, it is called the VHVI unit (very high viscosity index), since base oils with a very high viscosity index are obtained in said unit. In the VHVI unit, to improve the properties In cold of a base oil, linear paraffins are isomerized to form branched paraffins (iso-paraffins). In addition, the cracking of hydrocarbons takes place to some extent.

There is a growing demand for transport fuels and high quality base oil components in terms of purity, emissions, cold flow properties and lubrication of petroleum products. For example, the demand for middle distillates used as basic components in the production of diesel fuel is increasing in terms of cold flow properties and cetane index. The cetane index is an indicator of the burning rate of diesel fuel. The most important characteristic for a base oil component is the viscosity index, that is, the measure of viscosity change with temperature variations. The high viscosity index of the base oil component indicates that its lubrication capacity is maintained over a wide temperature range.

Several new technological developments have tried to meet the growing demand for improved petroleum-based products. US 2004/0256287 A1 discloses a hydrocracking process of a waxy hydrocarbon feedstock, such as waxy Fischer-Tropsch hydrocarbons, in the presence of a hydrocracking catalyst. The hydrocracking effluent is hydroisomerized in the presence of a hydroisomerization catalyst. The hydroisomerization effluent is fractionated to provide a heavy fraction and a medium distillate fuel, and the heavy fraction is dewaxed to provide a lubricating base oil having a viscosity index greater than 130.

US 2009/0065393 A1 discloses a process for obtaining a petroleum distillate in which a paraffin-based wax, such as Fischer-Tropsch wax and / or slack wax, is subjected to a cracking procedure in the presence of a catalyst, followed by hydrogenation of the olefinic intermediate obtained in the presence of a catalyst, and recovery of the distillate.

Documents US2007 / 175794 and US6315891 disclose production processes of base oils by hydrocracking a raw material comprising a mixture of VGO and Fischer-Tropsch wax. Document US8404912 discloses a process for producing base oils by hydrocracking a mixture of VGO and a heavy wax derived from the pyrolysis of plastic.

There is still a need for an efficient, simple and economical process for the production of medium distillates and lubricating base oils with a very high viscosity index of high quality and with high yields from available feeds and still improving product quality. . The middle distillates and base oils desirably have a high cetane number and a high viscosity index, respectively.

Brief Description of the Invention

The present invention provides a method according to claim 1.

Vacuum diesel is a petroleum-based heavy hydrocarbon distillate that is widely used as a raw material in fluid catalytic crackers to produce a wide range of valuable products for various applications, such as gasoline, diesel fuel and base oil. VGO contains a large amount of cyclic and aromatic compounds, as well as sulfur and nitrogen, which prevent their conversion to valuable high quality end products. As a rule, the quality of the VGO influences the quality of the final products. High quality Group III base oils with high viscosity index can be produced from suitable VGOs with good yields. However, a further increase in the viscosity index inevitably results in lower unwanted yields.

Surprisingly, in the present invention it was found that high quality medium distillates and lubricating base oils with high yields can be produced when a raw material for the general hydrocracking and catalytic dewaxing process is composed of VGO and wax. In addition, it was surprisingly found that the viscosity index of a base oil increased, without compromising performance, when wax was used in combination with VGO in the production of the base oil, compared to the viscosity index of a base oil produced from VGO only. It was also found that by introducing the wax together with the VGO into a hydrocracker, the performance of the hydrocracker catalyst was improved. In addition, the shelf life of the hydrocracking catalyst was extended. In addition, medium distillates with an improved cetane index and base oil with an increased viscosity index with good yields were produced.

A beneficial advantage of the process of the invention is that the strict quality requirements of VGO as a suitable raw material can be negotiated when wax is introduced into the raw material. In general, the appropriate quality of the raw material is adjusted using the VGO and the wax. In practice, this means that in the process of the invention lower quality VGO can be used with higher quality wax, including a smaller amount of impurities, and vice versa, and still produce high quality products. This feature allows VGO and waxes to be used in a wider quality range and provides an economic advantage.

The procedure is efficient, simple and economical.

Brief description of the drawings

Figure 1 schematically shows an embodiment of the process of the invention.

Figure 2 shows an effect of slack wax on the viscosity index (VI) of the base oil as a function of kinematic viscosity (KV).

Detailed description of the invention

In one aspect, the present invention provides a method according to claim 1.

In the present invention,

the term "slack wax" means a crude wax produced by cooling and wax distillate by pressing with solvent;

the term "vacuum diesel (VGO)" means a hydrocarbon product obtained from vacuum distillation of crude oil;

The term "Group III base oil" means a paraffinic base material that contains sulfur <0.03% by weight, saturates> 90% by weight and has a viscosity index of> 120.

The raw material suitable for use in the process of the invention normally comprises at most about 0.18% by weight of nitrogen, at most about 2% by weight of sulfur, and about 45% by weight of aromatic compounds.

The wax used is the slack wax. The slack wax is provided as an unpurified slack wax obtained from dewaxing with solvent from a waxy oil feed.

The wax is combined with VGO to provide a raw material that comprises the VGO as the main component and the wax as a minor component. In one embodiment, the raw material comprises a maximum of approximately 30% by weight of wax, the rest being the VGO. In another embodiment, the raw material comprises a maximum of approximately 25% by weight of wax. In yet another embodiment, the raw material comprises at most about 20% by weight of wax. In one embodiment, the raw material comprises 1-25% by weight of wax. In another embodiment, the raw material comprises 10-20% by weight of wax. In each embodiment, the rest is the VGO.

The raw material comprising wax is subjected to a hydrocracking stage. In the hydrocracking stage, heteroatoms such as N and S are removed, larger long chain hydrocarbons are cleaved into smaller short chain hydrocarbons and / or some cyclic hydrocarbons are opened to form linear and / or branched hydrocarbons. In addition, the dearomatization of aromatic compounds and the isomerization of hydrocracked molecules can also occur to some extent in the process. However, the cleavage of the hydrocarbons from the wax in the hydrocracking stage is not as extensive as that of the VGO.

Hydrocracking is normally performed in the presence of a hydrocracking catalyst. Hydrocracking catalysts suitable for use at this stage are well known to one skilled in the art. The hydrocracking catalyst may be arranged in one or more layers in a fixed bed. The catalyst can also be arranged in a progressive catalyst bed. Alternatives for the proper arrangement of the catalyst are well known to one skilled in the art.

In one embodiment, the raw material is first subjected to a hydrotreatment stage before the hydrocracking stage. The hydrotreatment step is carried out under conditions in which all heteroatoms, such as oxygen, sulfur and / or nitrogen present in the raw material, are removed. Also the aromatic compounds are normally saturated at this stage. At this stage there is no substantial cracking of the hydrocarbons in the raw material. The hydrotreatment stage before hydrocracking guarantees a good hydrocracking performance and improves the performance of the products produced in the subsequent hydrocracking. Hydrotreatment is usually performed in the presence of a catalyst. Catalysts suitable for use at this stage are well known to one skilled in the art. The catalyst may be arranged in one or more layers in a fixed bed. The catalyst can also be arranged in a progressive catalyst bed. Alternatives for the proper arrangement of the catalyst are well known to one skilled in the art.

The hydrotreatment and hydrocracking steps can be carried out in a single reactor or in separate reactors. When the two stages are carried out in separate reactors, the hydrotreatment reactor is arranged upstream of the hydrocracking reactor.

The hydrogen feed rate per raw material in the hydrocracking stage, which optionally includes a hydrotreatment stage, is approximately more than 1000 Nm3 / m3. Hydrocracking is normally carried out at a pressure in the range of about 120 to about 170 bar. In a mode of embodiment, the pressure is about 150 bar. The temperature is in the range of about 350 ° C to about 450 ° C.

The VGO and the wax that form a raw material can feed the hydrocracking reactor as separate or combined streams in a single stream that feeds the reactor.

The first effluent obtained from the hydrocracking stage is fractionated by distillation, whereby at least a lower fraction and a medium distillate fraction are obtained. An adequate quality of fuel oil is achieved for the middle distillate fraction and is suitable for use as a component in diesel fuel. The lower fraction is mainly composed of linear paraffins and naphthenes. The fractionation of the first effluent also produces a quantity of light gaseous hydrocarbons.

In one embodiment, for further refining, the lower fraction is subjected to a dewaxing step. In the dewaxing stage, the waxy n-paraffins are isomerized to provide branched iso-paraffins. Isomerization of hydrocarbons is desired and, in general, improves the cold flow properties of a base oil. Dewaxing is usually performed in the presence of a dewaxing catalyst. Dewaxing catalysts suitable for use at this stage are well known to one skilled in the art.

The dewaxing step provides a second effluent that is fractionated in a distiller to provide medium distillate and high quality base oil. Lighter gaseous hydrocarbons are also obtained. A Group III base oil that desirably has a high viscosity index of> 130 and a medium distillate with a high cetane index and improved cold flow properties are achieved. The middle distillate obtained from the dewaxing step can be used as diesel fuel as such or as a mixing component.

The present invention can be a discontinuous process or a continuous process.

An example of an arrangement that can be used to carry out the process of the invention is shown in Figure 1. Referring to the figure, the arrangement for producing oil-based components comprises a hydrocracking reactor A for cracking a waxy feed to provide a first effluent 4, a first distiller B, a dewaxing unit C and a second distiller D. The reactor Hydrocracking A comprises at least one inlet for supplying a raw material to the hydrocracking reactor A and an outlet for discharging the first effluent 4 from the hydrocracking reactor A. In one embodiment of the invention, the hydrocracking reactor A comprises at least two inlets, one for wax 2 and one for hydrogen 1 and VGO 3. In the figure, hydrocracking reactor A comprises a catalytic hydrotreatment zone HT and a catalytic hydrocracking zone HC, the hydrotreatment zone located upstream of the hydrocracking zone. The catalysts in each of the two zones can be arranged in one or more beds. In addition, the beds can be progressive with respect to the amount of catalyst employed. Proper arrangement and progression of the catalyst are well known to one skilled in the art. Alternatively, the hydrotreatment zone and the hydrocracking zone can be arranged in individual reactors, the hydrotreatment reactor located upstream of the hydrocracking reactor (not shown in Figure 1).

The first distiller B is in a flow connection with the hydrocracking reactor A to fractionate the first effluent 4 to provide at least a lower fraction HCB and a middle distillate fraction MD. The first distiller B comprises an inlet to supply the first effluent 4 to the first distiller B and at least one outlet to discharge the lower fraction HCB and a middle distillate fraction MD. The flow connection between the hydrocracking reactor A and the first distiller B is arranged through a pipe connection between the outlet of the hydrocracking reactor A and the inlet of the first distiller B. The first distiller B is disposed downstream of the reactor of hydrocracking A. The dewaxing unit C is in a flow connection with the first distiller B to dewax the lower fraction HCB to provide a second effluent 6. In one embodiment, the unit C is a solvent dewaxing reactor. The dewaxing unit C comprises an inlet for supplying the lower fraction HCB to the dewaxing unit C and an outlet for discharging the second effluent 6. The flow connection between the first distiller B and the dewaxing unit C is arranged through a pipe connection between the outlet of the first distiller B that discharges the lower fraction HCB and the inlet of the dewaxing unit C. The dewaxing unit C is disposed downstream of the first distiller B. The second distiller D is in a connection of flow with the dewaxing unit C to fractionate the second effluent 6 to provide at least a fraction of medium distillate mD and base oil. The second distiller D comprises an inlet for supplying the second effluent 6 to the second distiller D and at least one outlet, but preferably two outlets, for discharging the middle distillate MD and the base oil. The flow connection between the dewaxing unit C and the second distiller D is arranged through a pipe connection between the output of the dewaxing unit C and the inlet of the second distiller D. The second distiller D is disposed downstream of the dewaxing unit C and comprises: at least one outlet for discharging the middle MD distillate and the base oil.

In a further aspect, the disclosure provides a provision for producing oil-based components, the apparatus comprising:

• a hydrocracking reactor A for cracking a waxy feed to provide a first effluent 4, said hydrocracking reactor A comprising at least one inlet to supply a raw material to the hydrocracking reactor A and an outlet for discharging the first effluent 4 from the reactor hydrocracking A;

• a first distiller B in a flow connection with the hydrocracking reactor A to fractionate the first effluent 4 to provide at least a lower fraction HCB and a middle distillate fraction MD, the first distiller B being disposed downstream of the hydrocracking reactor TO;

• a dewaxing unit C in a flow connection with the first distiller B to dewax the lower fraction HCB to provide a second effluent 6, the dewaxing unit C being disposed downstream of the first distiller B; Y

• a second distiller D in a flow connection with the dewaxing unit C to fractionate the second effluent 6 to provide at least one medium distillate MD and base oil, the second distiller D being disposed downstream of the dewaxing unit C and It comprises at least one outlet to discharge the MD medium distillate and the base oil.

The following examples are provided for a further illustration of the invention without limiting the invention thereto.

Example

A raw material comprising 20% by weight of slack wax and the rest of VGO was introduced into a hydrocracking reactor comprising a hydrotreatment zone and a hydrocracking zone. The sulfur and nitrogen content of the raw material was 1.3% by weight and 0.079% by weight, respectively. The viscosity index of the raw material was 106.

The raw material was introduced into the hydrocracking reactor at a temperature of approximately 400 ° C and at a pressure of approximately 132 bar. The hydrogen feed per raw material was 1.1 l / l.

As a reference, 100% VGO raw material was introduced into the hydrocracking reactor under the same conditions.

The hydrocracking reactor effluent was fed to a distiller. A lower fraction (HCB) and a fraction of the middle distillate were obtained. The yield of the lower fraction with the addition of 20% by weight of slack wax to the VGO was increased from 31% to 35% compared to a VGO feed without slack wax. The cetane number of a fraction of the middle distillate increased from 60 (100% VGO) to 64 (80% VGO / 20% slack wax).

The lower fraction was dewaxed with solvent (SDW) to provide additional medium base oil and distillate. Catalytic dewaxing processes are specially developed to improve the cold properties of base oil products without sacrificing the viscosity index. Therefore, s Dw can be used as an indicator of the viscosity index also of the catalytically dewaxed product. The SDW is also a procedure generally accepted and used in the field and correlates well with catalytic dewaxing.

Figure 2 shows that the viscosity index of the base oil was remarkably higher with the addition of 20% by weight of slack wax than that of the pure VGO feed. The base oil obtained from solvent dewaxing, with a viscosity index of at least 130, was achieved even with 4 cSt of product. Figure 2 also shows that the viscosity index of the base oil is increased by more than about 10 units compared to that of the base oil that is prepared from VGO without wax.

It will be obvious to one skilled in the art that, as technology advances, the inventive concept can be implemented in several ways. The invention and its embodiments are not limited to the examples described above, but may vary within the scope of the claims.

Claims (5)

1. An oil based component production process, comprising the steps of: - provide VGO and slack wax; - combine VGO as a main component and slack wax as a minor component to provide a raw material; - subject the raw material to a hydrocracking stage to provide a first effluent; - fractionating the first effluent to provide at least a lower fraction and a medium distillate fraction; - recovering the lower fraction and the middle distillate fraction, where the raw material comprises a maximum of 30% by weight of slack wax and the slack wax is provided as unpurified slack wax obtained from solvent dewaxing of a waxy oil feed . 2. The method of claim 1, wherein - the lower fraction is subjected to a dewaxing step to provide a second effluent; - the second effluent is fractionated to provide at least one medium distillate and a base oil; - middle distillate and base oil are recovered. 3. The method of any one of the preceding claims, wherein the raw material comprises a maximum of 25% by weight of slack wax, more specifically a maximum of 20% by weight, even more specifically 1-25% by weight, even more specifically 10-20% by weight, the rest being the VGO. 4. The process of any one of the preceding claims, wherein the raw material comprises a maximum of 0.18% by weight of nitrogen, a maximum of 2% by weight of sulfur, and approximately 45% by weight of aromatic compounds . 5. The method of any one of the preceding claims, wherein the raw material is subjected to a hydrotreatment stage before the hydrocracking stage.