KR0167732B1 - Process for simultaneous production of fuel oils and specialty oils by a single unit hydrocracking process - Google Patents

Abstract

The present invention relates to a method capable of producing not only fuel oil but also various types of special induction by combining a fuel oil hydrocracking process and a selective hydrocracking process for producing special oil in a single unit process. More specifically, the present invention relates to a method for producing a special oil by using a hydrogenated residual oil that has been converted into a fuel flow path in a fuel oil hydrocracking step, comprising the steps of: hydrocracking a reduced pressure gas oil in one step, Separation in a distillation tower, selective hydrocracking of the hydrocracked residual oil with a catalyst to effect hydrotreating and simultaneous dewaxing of the hydrocracked residual oil, separation of the effluent from the two-step selective hydrocracking process in the atmospheric distillation column with fuel oil And a method for simultaneously producing a fuel oil and a high-grade special oil in a single unit process including a step of separating a special oil and a step of distilling the separated special oil. It is possible to reduce the investment cost and to simplify the operation, and the first step hydrolysis and the second step selective hydrolysis Defined severity can also adjust the production flexibly according to changes in demand for specialty oils and fuel oils of various different grades and quality that can be adjusted, and the quality can also be adjusted.

Description

Simultaneous production of fuel oil and special oil by single unit hydrocracking process

FIG. 1 is a schematic process diagram of fuel oil hydrocracking or lube oil raw material hydrocracking comprising a conventional one-stage reactor. FIG.

FIG. 2 is a schematic flow diagram of a fuel oil hydrocracking or lubricating oil raw material hydrocracking comprising a conventional one-stage two-reactor (schematic diagram of continuous hydrotreating and hydrocracking).

FIG. 3 is a schematic diagram of the conventional process of hydrocracking of fuel oil or of hydrocracking of lube oil (step 1, continuous hydrocracking and hydrocracking process, step 2, hydrocracking process) comprising two stages of three reactors.

FIG. 4 is a schematic flowchart of the hydrocracking process (step 1, hydrocracking process, step 2, selective hydrocracking process (simultaneous dehydration and hydrogenation stabilization process)) capable of simultaneously producing the fuel oil and the special oil according to the present invention.

FIG. 5 is a schematic process diagram for explaining FIG. 4 in more detail; FIG.

DESCRIPTION OF THE REFERENCE NUMERALS

Atmospheric Residue (AR): Atmospheric Residue

VR (Vacuum Residue): Vacuum Residue

AT (Atmospheric Tower): Atmospheric distillation tower

VGO (Vacuum Gas Oil): Vacuum gas oil

VTI (Vacuum Tower 1): Vacuum distillation column R1: VGO hydrogenation reactor

R2: VGO hydrolysis reactor R3: Selective hydrocracking reactor

VT2 (Vacuum Tower 2): vacuum distillation tower

3: primary hydrocracking reactor 4: secondary hydrocracking reactor

5,14: Gas-liquid separator 6-1: Amine absorber

6-2: Water washing tower 8: Atmospheric distillation column

11: Decompression column 13-1, 13-2: Selective hydrocracking reactor

The present invention combines the fuel hydrocracking process and the selective hydrocracking process for the production of special oil into a single unit process, so that various kinds of specialty oil And simultaneously producing fuel oil and special oil which can be produced at the same time.

Since the hydrocracking process began to be introduced in the 1960s, the hydrocracking process was mainly aimed at the production of fuel oil such as naphtha. However, since the late 1960s, hydrocracking processes for producing raw materials of lube base oil using amorphous catalysts Has begun to be introduced.

A typical fuel oil hydrocracking process consisting of one reactor as shown in US Pat. No. 3,308,055 of 1967 by Chevron is shown in FIG. In FIG. 1, the hydrocarbons of the reduced-pressure gas oil are hydrocracked and separated by the atmospheric distillation, and the remaining residual fuel oil is sent to the BC tank or recycled to be decomposed again. And a part of them is recycled again to hydrolyze to produce fuel oil.

Meanwhile, in order to produce the lubricating oil using the above-mentioned lubricating oil raw material, it is necessary to satisfy the requirements such as the suitable boiling point and viscosity, the viscosity index, the pour point and the stability required for the lubricating oil The above lube oil raw materials have appropriate viscosity, boiling point and high viscosity index, but they have a high pouring point and poor stability, so that the dewaxing process for lowering the pour point and the improvement of the stability of the lubricating oil Lubricating oil is produced after the hydrogenation stabilization process.

In the process shown in FIG. 1, the conversion index is 20 to 40% per pass and the viscosity index is 100 or more. However, since the amorphous catalyst is used, the lubricant oil having the high viscosity index required for the high- There is a limit to obtaining raw materials.

In the 1970s and 1980s, zeolite catalysts were introduced to hydrolyse various feedstocks and enable high conversion rates per pass. However, the above-mentioned pressure-reducing gas oil is composed of hydrocarbon compounds having 20 to 40 carbon atoms and containing a large amount of impurities such as sulfur and nitrogen compounds. Of these impurities, in particular, the nitrogen compound is a zeolite catalyst Lt; RTI ID = 0.0 > catalyst poison. ≪ / RTI > Therefore, in order to remove such impurities to protect the hydrocracking catalyst and to carry out the denitrification reaction by the hydrogenation treatment, as shown in the second figure (except for the case of producing the lubricant oil) A single-stage continuous hydrotreating-hydrocracking process was introduced in which a hydrotreating reactor filled with an amorphous catalyst was introduced.

As a result of hydrocracking process, the heavy oil fraction above 350 ° C is hydrolyzed and converted to light oil such as LPG, naphtha, kerosene, light oil and the like. The hydrotreating reaction and the hydrocracking reaction are carried out using a single catalyst or two different catalysts (these two catalysts are used together at the bottom and the bottom of the catalyst bed) in a single reactor as shown in FIG. 1, or As shown in FIG. 2, two different catalysts can be used in two reactors. Subsequently, the two products undergo the reaction to separate hydrogen from the gas-liquid separator and produce the various grades of fuel oil described above in the atmospheric distillation process.

Generally, since the conversion per pass is not 100%, it is impossible to decompose completely, so that the hydrolysis residue oil which has not been converted is present, which can be recycled and converted into fuel oil or used as a lubricant oil or BC fuel .

Therefore, IFP of France developed a new zeolite catalyst to increase the yield of kerosene and light oil and to control the operation severity in a wider range, instead of reducing the yield of naphtha, which is a disadvantage of conventional zeolite catalyst. The utility of high-grade lubricant oil is well documented in the technical data of France IFP published at the Petroleum Refining Conference of Japan Petroleum Association in November 1992, as in No. 2 (including the manufacture of lube raw materials) (A. Hennico, A . Billon, P. H Bigeard and JP Peries, IFP's New Flexible Hydrocracking Process Combines Maximum Conversion With High Viscosity, High VI Lube Stocks, Revue De L'Institut Francais Du Petrole, Vol. 48, No. 2, 139, 1993). With this method, the conversion rate per pass can be adjusted to 20 to 90%, and it is possible to produce a conventional lube oil feedstock for the production of lube oil hydrocracking process (conversion rate: 20 to 30%) and fuel oil The classification of the fuel oil hydrocracking process (conversion rate: 50 to 90%) is eliminated, and the degree of severity can be changed according to the purpose.

As described above, it is also possible to increase the conversion rate per pass to 50 to 70% by introducing a zeolite catalyst, thereby producing a hydrocracked residue of an ultrahigh viscosity index having a viscosity index of 130 or more, which can be used as a raw material for lubricating oil.

However, the hydrocracked residual oil has a high viscosity index and has good properties as a lubricating oil. However, it contains a lot of lead (wax) oil, which is a normal paraffinic component (having 18 or more carbon atoms) Resulting in solidification at low temperature, which has a fatal effect on the performance of the lubricating oil. Therefore, in order to have a sufficiently low pour point that the lubricating oil is satisfactory, it is necessary to undergo a dehydration process. On the other hand, when lead oil is selectively decomposed, olefins are generated partly. These olefins have a bad influence on the color of the lubricant oil, and they produce polymerized sword, which also has a bad influence on the stability. In addition, since sulfur and nitrogen compounds remaining after hydrocracking are removed to some extent during catalyst withdrawal, aromatic compounds are not removed, and therefore it is necessary to remove these compounds by hydrogenation reaction. Therefore, in order to increase the color and stability of the dehydrated lubricant oil as in the second drawing (including the production of the lubricant oil), it is necessary to perform the hydrogenation stabilization step after the dewaxing step.

On the other hand, in the hydrocracking process as described above, a two-stage hydrocracking process is applied when the amount of raw material is 35,000 B / D or more, or nitrogen is contained in raw material oil at 2,500 ppm or more. As shown in FIG. 3, the two-stage hydrocracking process is a one-stage batch-type hydrocracking process in which about 50% hydrocracking is performed and then the remaining hydrocracking residue is distilled under atmospheric distillation, And then recirculating it to the first-stage hydrocracking reactor.

In addition, in the above-mentioned recycling type hydrocracking process, the polycyclic aromatic compounds which are not hydrolyzed continuously accumulate and become catalyst poison, so it is necessary to extrude 5 to 10% of the amount of the raw materials based on the amount of feedstock. Thus, the actual overall conversion rate will remain at 90 to 95%. In all of the above-mentioned processes, the hydrocracked residual oil may be recycled again to decompose the fuel flow path, or may be converted into lead silane compounds having a small amount of impurities such as sulfur and nitrogen compounds and become high-viscosity lead-acid compounds, thereby becoming a raw material for high-grade lubricant oils.

As described above, if the hydrocracking process, dewaxing (solvent dehydration or catalyst desorption) and hydrogenation stabilization process, which are required for producing a high-quality lubricant oil, are separately installed, there is a problem that a large investment cost is required and the process becomes complicated. The production process of the lubricant oil is independent of each other, so that it is not possible to produce high-quality lubricant oil or special oil (hereinafter referred to as special oil) in a single process. Therefore, if the two processes of the hydrocracking process and the lubricant oil production process can be simplified, there are many advantages.

As described above, in the conventional methods, the hydrocracking process and the dewaxing and hydrogenation stabilization processes, which are essential for producing a high-quality lubricant oil, are separately installed, so that a large investment cost is required and the process is complicated. Tanks, vacuum distillation towers, and two separate recirculating gas processes have been inefficient in many ways such as investment cost, construction period, required area, and ease of operation. Also, there has been no proposal for a continuous / efficient recirculation to the fuel oil hydrocracking process of the remaining lubricating oils other than the special oil of the required grade.

Accordingly, the present inventors have found that the fuel oil hydrocracking process and the dewaxing and hydrogenation stabilization process can be performed in a single unit process, and the dewaxing and hydrogenation stabilization process can be performed at the same time, And a method of effectively recirculating the produced oil has been studied and experimented for a long time. As a result, the inventors invented a new production method of fuel oil and special oil which could not be achieved by the existing prior methods.

The present invention is based on the simple refinement of the recycling-based two-stage hydrocracking process shown in FIG. 3, which is based on the fuel oil, to provide simultaneous dewatering and hydrogenation stabilization (hereinafter referred to as selective hydrocracking) The present invention relates to a process capable of simultaneously producing not only fuel oil but also a finished lubricating oil product satisfying high-quality special oil specifications in a single unit process. A process according to the present invention for simultaneously producing such a fuel oil and a special oil is shown in FIG. 4, wherein the first stage is a hydrocracking process and the second stage is a selective hydrocracking process for simultaneous deprotonation and hydrogenation stabilization.

According to the present invention, by using a zeolite catalyst carrying palladium instead of a decomposition catalyst in a two-stage fuel oil hydrocracking reactor and installing only an amine absorption apparatus for purification of a recycle gas without installing a separate dewatering and hydrogenation stabilization reactor, In the hydrocracking process, fuel oil and high-grade special oil can be continuously produced at the same time. This is possible by operating at the same pressure as the operating pressure in step 1, a two-step selective hydrogenation cracking process hydrogenated cracking process, the pressure range is preferably 100~250㎏ _f / ㎠, more preferably 150~200㎏ _f / ㎠ .

In the present invention, by continuously and selectively hydrocracking the hydrocracked residual oil from the bottom of the atmospheric distillation tower, the additional tank necessary for storing hydrocracked residual oil and the reduced pressure distillation column necessary for block operation can be reduced in the prior art. That is, the existing fuel oil two-stage hydrocracking process can be greatly reduced by simply replacing the catalyst, recycling gas purification unit and vacuum distillation tower, and the additional investment cost, required area and construction period can be greatly reduced. In the first step hydrocracking process, This is a new concept production method that can produce flexible fuel oil and special oil at the same time and can enhance the quality of lubricant by controlling the degree of operation severity by putting the hydrocracked residue produced by the control into the 2 step selective hydrocracking process There is a feature that can change.

Further, in the present invention, the selective hydrocracking reactor of the second stage is closed and the hydrocracked residual oil obtained in the first stage process is directly introduced into the reduced pressure distillation column installed in the two-step selective hydrocracking process, It is possible to switch to a process of simultaneously producing a raw material for lubricating oil. That is, according to the demand fluctuation of the fuel oil and the lubricant oil, it is possible to perform two functions with one decompression distillation column, thereby effectively replacing the separation function of the lubricant oil material and the separation function of the lubricant oil.

The present invention relates to a method for producing a special oil using a hydrocracked residual oil which is converted into a fuel flow path in a fuel oil hydrocracking process,

A step of hydrocracking the reduced pressure gas oil in one step,

Separating the hydrocracked fuel oil from the atmospheric distillation column,

A step of hydrolyzing the hydrogenolubilized residual oil in two stages by using a catalyst to stabilize hydrolysis with dehydration,

Separating the effluent from the two-step selective hydrocracking process into a fuel oil and a special oil in an atmospheric distillation column, and

And a step of subjecting the separated special oil to a reduced-pressure distillation.

In the present invention, supplementary hydrogen is supplied in the first-stage hydrocracking process and the gas separated in the first-stage hydrocracking process and the second-stage selective hydrocracking process is recycled to one compressor, The first step hydrocracking process may be directly fed without removal of hydrogen sulphide and ammonia, the two step selective hydrocracking process may include removing hydrogen sulphide through an amine absorption tower, removing ammonia through a water scrubber and then supplying recycled hydrogen have.

In another aspect of the present invention, the effluent of the first-stage hydrocracking process is produced in the atmospheric distillation column between the light oil fraction and the hydrocracked residue, and the super purity special oil is produced. When the pour point is below -40 ° C, Stage hydrocracking process, it has an ultra-low pour point of -40 ° C or less and a very low content of aromatic compounds (about 1.0 _wt% or less), a high-grade starch having a high viscosity index A method for obtaining a hard special oil is also provided.

According to another aspect of the present invention, there is also provided a method of recycling a part of the special oil separated from the vacuum distillation column to a two-step selective hydrocracking reactor to further improve the quality or to recycle it into a first step hydrocracking process do.

It may also provide a flexible operating mode through parallel or serial installation of a two-step selective hydrocracking reactor.

Hereinafter, the present invention will be described in detail with reference to FIG.

Pressure gas having a suitable boiling range oil (VGO), together with the bulk (mixed at the same time input to the process) or blocks (in each separate step in accordance with the distillation range) in supply lines (1) replacement of hydrogen (Makeup H ₂₎ introduced into the Is introduced into the primary hydrocracking reactor (3) through the supply line (2). In the hydrocracking reactors (3 and 4), two reactors are constituted in series, and the first hydrocracking reactor (3) is filled with an amorphous silica alumina catalyst carrying a Ni / Mo based metal and a second hydrocracking reactor 4) is filled with a modified Y zeolite catalyst carrying a Ni / Mo-based metal. The reduced pressure gas oil is subjected to a pretreatment such as desulfurization, denitrification and some hydrocracking reaction in the first hydrocracking reactor (3), and then introduced into the second hydrocracking reactor (4) and hydrolyzed. While the reduced pressure gas oil passes through the hydrocracking process, the conversion rate per unit pass can be adjusted from 20% to 90% to operate flexibly.

The effluent from the secondary hydrocracking reactor (4) is introduced into a high pressure gas / liquid separator (5) and separated into gas and liquid products. The gas includes hydrogen sulfide and ammonia generated in the reaction, and is introduced into a high-pressure amine absorption unit (6-1) and a water washing tower (6-2) in order to remove such contaminants from the gaseous products. Or recycled to the primary hydrocracking reactor (3) via line (7). Since the sulfide catalyst is used in the hydrocracking process, the recycle hydrogen introduced into the hydrocracking reactor need not be highly pure. As is known, some hydrogen sulfide acts more favorably on the activity of the catalyst when it is present in the recycle hydrogen.

The liquid reaction product separated in the gas-liquid separation (5) is fed into the atmospheric pressure refueling column (8) at a very low pour point which is used as a fuel oil component such as LPG, naphtha, kerosene, light oil, oil and the like, spindle oil, Super-hard special oil and hydrogen-decomposition residue oil. As the feed oil supplied to the hydrocracking reactor is hardened, the pouring point of the super hard special oil in the lubricating oil component is increased. In the light oil having a high pour point, it is introduced into the two-stage selective hydrocracking reactor through the line (9) to greatly reduce the pour point and aromatic compound content. When the pour point is sufficiently low, It is separated and used special flow channel. In this case, it is not necessary to install a separate dryer by putting it in the decompression distillation column. On the other hand, in the above operation mode, the viscosity index is high and the pour point is very low It is one of the characteristics of the present invention that a special oil of excellent quality having a low aromatic compound content is selectively produced.

The hydrocracked residual oil separated in the atmospheric distillation column 8 is introduced into the selective hydrocracking reactors 13-1 and 13-2 via the line 9 together with the recycle hydrogen introduced into the line 12. However, in the selective hydrocracking reactors 13-1 and 13-2 of the present invention, recycle hydrogen (Recycle H ₂ ) is used to increase the amount of hydrogen introduced into the reactor It is easy to increase. At this time, the increased amount of hydrogen has an advantage that it can enhance the hydrogenation and dehydrogenation function in the selective hydrocracking reaction, thereby further promoting the stabilization reaction, that is, the desulfurization, the denitrification, the olefin and the aromatic compound saturation reaction.

The selective hydrocracking reactors 13-1 and 13-2 can reduce the LHSV to 1/2 by installing two identical reactors filled with the same catalyst (a ferrite catalyst carrying a Group VIII noble metal) in parallel, It is designed so that two reactors can be connected in series in case the temperature increase per catalyst bed is severe or the catalyst is replaced with a stabilization catalyst.

In these cases, it is possible to combine the two processes more effectively to the working pressure of the two-step selective hydrogenation cracking process can be a high pressure (150~200㎏ _f / ㎠) similar to the first stage hydrogenation cracking process. In addition, each reactor is filled with a fuel oil hydrocracking catalyst (modified Y zeolite) for fuel oil production only, or a selective hydrocracking catalyst having a dewaxing and hydrogenation stabilizing function as in the present invention is filled, And can operate flexibly according to the demand situation of fuel oil and special oil. The reaction products of the selective hydrocracking reactors (13-1 and 13-2) are separated into various special oil components in the reduced pressure distillation column (11) after passing through a high-pressure gas-liquid separator (14).

In the process shown in FIG. 5, the first stage hydrogenation process and the hydrogenolysis process are composed of two reactors having different catalysts. Since the conversion rate per pass can be controlled by controlling each operation condition, the first stage hydrocracking process It is possible to produce a variety of hydrocracked residues while using various kinds of gas under pressure. In the second step selective hydrocracking process, a special oil of high quality can be produced without a separate hydrothermal stabilization process by performing dewaxing and stabilization at the same time as dewaxing.

In this process, it is important to set appropriate operating conditions in a multi-step process, and the operating conditions for each step are shown in Table 1 below.

Hereinafter, specific embodiments according to the present invention are described in Examples. The examples are intended to illustrate the invention and are not intended to limit the scope of the invention.

[Example 1]

In this Example, the feedstock and the conversion ratio of the hydrocracking reaction were changed to prepare a hydrocracked residual oil. There are three types of distillation ranges separated from the vacuum distillation column: LVGO (Light Vacuum Gas Oil), MVGO (Medium Vacuum Gas Oil) and HVGO (Heavy Vacuum Gas Oil) , Which can be supplied to the hydrocracking fixation in bulk or as a block. The conversion rate per pass at this time is 20 to 90%, and the untreated oil (called hydrocracked residue in the present invention) remaining without decomposition is present.

In addition, the first-stage hydrocracking reaction produces various hydrocracked residues depending on the feedstock and operating conditions and can be operated flexibly according to the supply and demand situation.

In this example, experiments were carried out in the range of 50% to 80% conversion rate while varying the feedstock (VGO of Arabian Light) of the first step hydrocracking reaction to prepare a hydrogenolysis residue as a feedstock for the 2-step selective hydrocracking reaction The characteristics of the hydrocracked residual oil according to the feedstock and the conversion rate are shown in Table 2 below.

The hydrocracking residues were produced by the fuel oil hydrolysis process. The amorphous catalysts containing Ni / Mo metal were used as the first hydrocracking catalyst and the modified Y zeolite catalyst was used as the second hydrocracking catalyst. Respectively. A temperature of 370 to 430 캜, a pressure of 158 kg / cm 2, an LHSV of 1.0 / 2.0 hr . In Table 2, alphabetic characters such as A-67, B-50, B-65 and C-65 indicate the kind of feedstock and the weight conversion rate in which the number of fractions of 360 or more is hydrocracked to oily fractions below 360 ° C.

As a result of the experiment, it was possible to obtain a high viscosity index of about 130 or more. At the same conversion rate, the viscosity index is low as the feedstock having a high viscosity, and as the conversion rate of the same feedstock is high, the viscosity becomes small and the content of aromatic compounds, sulfur and nitrogen becomes small The thermal stability has an appropriate conversion rate which increases and decreases as the conversion rate increases, depending on the feedstock.

[Example 2]

Two - step hydrocracking reaction was carried out using the hydrocracked residual oil produced at the same conversion (65%) while changing the feedstock of the first - step hydrocracking reaction to produce a special oil.

The experiments were carried out at a pressure of 158 kg / ㎠ and a hydrogen flow rate of 4,000 SCF / bbl, the same as in the hydrocracking process. The LHSV and temperature were adjusted so that the pouring point of the special oil produced was -12.5 ° C to 15.0 ° C. Step 2 selective hydrocracking using the feedstock produced in the first-step hydrocracking process is shown in Table 3 below.

The higher the boiling point of the feedstock of the first stage hydrocracking reaction (D <C <B), the higher the yield, viscosity and viscosity index of the special oil produced in the second step selective hydrocracking process. Experimental results show that there is a relationship between the primary hydrocracking unit and the secondary selective hydrocracking unit so that the quality of the product can be controlled by changing only the feedstock of the first stage hydrocracking unit depending on the viscosity of the special oil and the requirements of the viscosity index .

[Example 3]

To investigate the effect of the change of conversion (or severity) on the two - step selective hydrocracking reaction when the feedstock of the first - stage hydrocracking reaction was constant, LHSV and temperature were measured at a pressure of 158 kg / ㎠, hydrogen flow rate of 4,000 SCF / Was adjusted so that the pouring point of the generated special oil was -12.5 ° C. The results of the 2-step selective hydrocracking according to the 1-step hydrocracking conversion are shown in Table 4 below.

As shown in Table 4, even when the feedstock of the first-stage hydrocracking reaction is used in the same manner, the quality of the hydrocracked residue supplied to the second-step hydrocracking reaction is changed by changing the conversion (or severity) The quality of the final product, that is, the special oil, is changed. In this case, the characteristic of the hydrocracking residue with lower conversion rate increases the severity of operation of the two-step selective hydrocracking process to obtain the same special oil pour point. In the case of water content, the special oil decreases and the super hard special oil increases. In addition, the characteristics of the special oil produced showed a tendency that the viscosity decreased and the viscosity index increased with the use of the hydrocracked residual oil having a high conversion ratio.

[Example 4]

Table 5 shows the quality of the special oil produced when the feedstock of the first step hydrocracking process is changed.

When C was used as a feedstock, a special oil was produced at a pour point (-12.5 ° C or less) suitable as a product. However, when D was used as a feedstock, the pour point tended to be somewhat higher.

This is due to the unconverted 300 to 360 ° C part as the low boiling point component is introduced into the first step hydrocracking unit. The pour point of this part is higher than that of the first step hydrocracking reaction It changes greatly.

In Case 3, the super-hard special oil with high pour point generated in Case 2 was supplied to the two-stage selective hydrocracking apparatus together with hydrocracking residue to improve the descent and stability of the pour point. As a result, the pour point, Bromine Index, heat and ultraviolet stability were greatly improved. Especially, ultrahigh pour point with pour point of -40 ℃ or less, extremely low aromatics content and high viscosity index was obtained.

On the other hand, the quality of the ultra-hard special oil obtained in Case 3 is higher than that of the super-hard special oil (P-8) obtained in the conventional lubricant hydrolysis process and the special oil (S-8) A high viscosity index of 20 or more, a low pour point and aromatic content, and excellent thermal stability.

[Example 5]

The characteristics of 100N and 150N of special oil, feed oil, special oil and separately produced simultaneously are shown in Table 6 below.

The yield of special oil produced under the reaction conditions of operating temperature 340 ° C, LHSV 0.5 and operating pressure 158㎏ / ㎠ was 75.8% using A-67 as a feedstock for the secondary selective hydrocracking reaction. When they were separated and at the same time producing 100N and 150N, their yields were 17.5% and 19.5%, respectively, based on reduced gas oil. The yield and characteristics of 60N, 100N and 150N can vary greatly depending on the mode of operation of the vacuum distillation column (simultaneous production or individual production) after bulk desoldering, and only the undesired specific parts of the lube oil separated from the vacuum distillation column The pour point may be lowered by selective recycling to the hydrocracking process, and special oils other than the special grade oil of the required grade may be sent to the BC tank or recycled to the first stage hydrocracking process to break down the rigid fuel flow path.

Claims (13)

A method for producing a special oil by using a hydrogenated residual oil remaining in a fuel oil hydrocracking process in a fuel oil hydrocracking process, comprising the steps of: hydrocracking a reduced pressure gas oil in one step, separating a hydrocracked fuel oil in an atmospheric distillation column A step of selectively hydrocracking the hydrocracked residual oil with a catalyst to effect hydrotreating with simultaneous dewaxing, separating the effluent from the two-step selective hydrocracking process into a fuel oil and a special oil stream in the atmospheric distillation column And a step of subjecting the separated special oil to a reduced pressure distillation. The process according to claim 1, wherein the catalyst used in the two-step selective hydrocracking process is a Dual Functional Catalyst having selective decomposition of wax and hydrogenation stabilization function. The method according to claim 1, wherein the operating pressures of the 1-step hydrocracking process and the 2-step selective hydrocracking process are the same. The method of claim 3 wherein the operating pressure is within the method 100~250㎏ _f / ㎠ range. The method of claim 4, wherein the operating pressure is 150~200㎏ _f / ㎠ within the range of ways. The method according to claim 1, wherein the recycle hydrogen is supplied at a flow rate of 6,000 to 10,000 SCFB to the one-step hydrocracking process, and the flow rate is 3,500 to 4,500 SCFB to the two-step selective hydrocracking process. The method according to claim 1, wherein the supplemental hydrogen is supplied in the first-stage hydrocracking process, the gas separated in the gas-liquid separator in the first-stage hydrocracking process and the gas-liquid separator in the second-stage selective hydrogenolysis process is recycled and compressed by a compressor, Wherein the hydrocracking process is provided directly without removal of hydrogen sulphide and ammonia, the two-step selective hydrocracking process includes removing hydrogen sulphide through an amine absorption tower, removing ammonia through a water scrubber, and then supplying recycled hydrogen. The process according to claim 1, wherein the effluent of the first-stage hydrocracking process is produced in the atmospheric distillation column between the light oil fraction and the hydrocracked residue oil and the super-hard special oil. If the pour point is lower than -40 ° C, When the pour point is high, it is added to the two-stage selective hydrocracking process to obtain a super-hard special oil having an ultra-low pour point of -40 ° C or less and an aromatic compound content of 1.0 _wt% or less and having a high viscosity index . A method according to any one of claims 1, 4 and 5, characterized in that no dryer is placed in the reduced pressure column to dry separately. The method according to claim 1, wherein a portion of each of the special oils separated in the reduced pressure column is recycled to a two-stage selective hydrocracking reactor for quality improvement. The method according to claim 1, wherein the effluent of each of the special oils isolated from the vacuum distillation column is recirculated to the first step hydrocracking process to convert the effluent to the fuel flow path. The method according to claim 1, wherein a plurality of two-step selective hydrocracking reactors are installed in parallel. The method of claim 1, wherein a plurality of two-stage selective hydrocracking reactors are installed in series.