RU2729791C1 - Diesel fuel hydroskimming method - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention describes a method for hydroskimming diesel fuel, involving heating raw material in form of a straight-run fraction of diesel fuel and / or corresponding fractions of secondary processes and / or mixture thereof in a tubular furnace, mixing it with hydrogen-containing gas, catalytic hydrodesulphurisation of obtained mixture in two series-connected reactors to obtain purified hydrogenated product and subsequent fractionation of purified hydrogenated in rectification column, purifying hydrogen-containing gas in an absorption column from hydrogen sulphide, characterized in that the feedstock is mixed with a hydrogen-containing gas and hydrogen, are subjected to preliminary heating in recuperative heat exchangers and preliminary catalytic hydrogenation in additional reactor, wherein in the second of two series-connected reactors there is provided catalytic hydrodearomatisation of hydrogenated product coming from the first of two series-connected reactors.

EFFECT: disclosed is a method for hydroskimming diesel fuel, which provides longer service life of catalysts and purification of initial diesel fuel from organosulphur compounds.

11 cl, 1 dwg

Description

The present invention relates to a method for hydrotreating diesel fuel and can be used in the processing of oil or gas condensate.

Hydrorefining of diesel fuel from organosulfur and aromatic impurities that impede the efficient operation of internal combustion engines and lead to environmental pollution is one of the largest-tonnage oil refining processes. While the requirements for the quality of diesel fuel were low, a 5-10-fold decrease in the total sulfur content was achieved as a result of catalytic hydrodesulfurization in a single reactor (Akhmetov S.A.

Deep processing technology of oil and gas. - Ufa: Gilem, 2002 .-- 672 p.).

As the requirements became more stringent and the level of permissible sulfur content decreased by standards from Euro-3 (350 ppm) to Euro-5 (10 ppm), the schemes of reactor blocks for hydrotreaters began to improve, moving from single reactors to more complex systems.

There is a known method for the conversion of hydrocarbon feedstock, including contacting the feedstock with hydrogen under the conditions of hydrotreating to obtain a hydrotreated product, and the hydrotreating conditions include a temperature of 250-480 ° C, a pressure of 10-150 bar and an average hourly feed rate of the feedstock 0.1-10 h ^-1 , treating the hydrotreated product by separating at least hydrogen from the hydrotreated product to obtain a hydrotreated product liquid stream having a temperature of 150-280 ° C, treating at least part of the hydrotreated product liquid stream by stripping at a temperature of 130-240 ° C and a pressure of 1 , 5-10 bar, to separate light products from the liquid stream of the hydrotreated product, in which the heavy hydrotreated product remains, separation of the heavy hydrotreated product in the separation zone at a reduced pressure of 0.005-1 bar and a temperature of 120-250 ° C into at least one gaseous a stripped fraction and at least a liquid stripped fraction , wherein at least part of the liquid stripped product is reheated and returned back to the separation zone, wherein at least part of said liquid stripped fraction is reheated by heat exchange between at least part of the liquid stream of the hydrotreated product and / or at least part of the heavy hydrotreated product (patent for invention RU 2543719 C2, IPC C10G 49/22, C10G 67/14, Appl. July 15, 2010, publ. 03/10/2015).

The disadvantage of the invention is the low degree of hydrodesulfurization of the feedstock hydrocarbon, which is achieved by means of one stage of hydrotreating.

A known method for hydrotreating diesel fuel by catalytic treatment in the presence of a hydrogen-containing gas at elevated temperatures and pressures to obtain a hydrogenated product,

separation of hydrogenated product to obtain a hydrogen-containing gas and a liquid phase and stabilization of the liquid phase, while in order to increase the degree of desulfurization, 15-25% of the liquid phase is recycled for mixing with the original diesel fuel (patent for invention RU 2323958 C1, IPC C10G 65/00, App. February 26, 2007, published May 10, 2008). The disadvantages of the invention are:

- decrease in the productivity of the installation due to the increase

loads due to recycling of the liquid phase for mixing with the original diesel fuel;

- increasing the material consumption of the method, a large consumption of the catalyst due to the recycle of the liquid phase.

There is also known a method for hydrotreating diesel fuel,

including fractionation of straight-run diesel fuel to obtain light and heavy fractions of diesel fuel, boiling within 180-300 ° C and 300-360 ° C, subsequent separate catalytic hydrotreating of the obtained light and heavy fractions of diesel fuel in parallel in two reactors in the presence of hydrogen-containing gas, separation of hydrogen-containing gas from hydrogenates and compounding of hydrogenates (Loginov S.A. Development of a new technology for the process of hydrodesulfurization of diesel fuels / S.A. Loginov, B.L. Lebedev, V.M.Kapustin et al. // Oil refining and petrochemistry. - 2001. - No. 11. - P. 67-74). The disadvantage of this method is the double fractionation of diesel fuel at the primary oil refining unit and at the hydrotreating unit, leading to an increase in energy consumption for the preparation of hydrotreating feedstock.

Also known is the closest to the claimed invention method of hydrotreating petroleum fractions at elevated temperature and pressure and circulation of hydrogen-containing gas in two stages in the presence of a package of alumina catalysts, including a protective layer, while the process is carried out at a temperature of 330-390 ° C, a pressure of 40-50 atm , the circulation of a hydrogen-containing gas 250-400 nm ³ / m ^{3 of the} feedstock, the space velocity of the feedstock feed 0.8-1.3 h ^-1 in the presence of a catalyst package, which includes in the first stage a catalyst of the protective layer as an upper retaining layer and an aluminum-nickel-molybdenum catalyst in as the lower layer with the following ratio of components, wt.%: catalyst of the protective layer - 3.0-10.0; alumina-nickel-molybdenum catalyst - the rest; at the second stage, the catalytic package includes an aluminum-cobalt-molybdenum catalyst or an aluminum-nickel-molybdenum catalyst as an upper layer and an aluminum-cobalt-molybdenum catalyst as a lower layer with the following ratio of components, wt%:

alumo-cobalt-molybdenum catalyst - 20.0-30.0;

aluminum-cobalt-molybdenum catalyst - the rest (patent for the invention RU 2353644 C1, IPC C10G 65/04, C10G 45/08, filed on November 14, 2007, published on April 27, 2009). The disadvantages of the invention are:

- low degree of diesel fuel hydrotreating;

- violation of the homogeneity of the flow of the reaction mixture and the emergence of the possibility of the formation of stagnant zones in the liquid phase and channeling in the gas phase due to the supply of raw materials to the reactors from the bottom up, which worsens the structure of flows in the catalyst bed and complicates the course of reactions.

When creating the invention, the task was to develop a method for hydrotreating diesel fuel, providing deep purification of the original diesel fuel from organosulfur, aromatic and other undesirable components, as well as increasing the service life of catalysts.

The problem is solved due to the fact that the method for hydrofining diesel fuel includes heating the feedstock in the form of a straight-run fraction of diesel fuel and / or the corresponding fractions of secondary processes and / or their mixture in a tube furnace, mixing it with a hydrogen-containing gas, catalytic hydrodesulfurization of the resulting mixture in two reactors connected in series to obtain a purified hydrogenated product and subsequent fractionation of the purified hydrogenated product in a rectification column, purification of a hydrogen-containing gas in an absorption column from hydrogen sulfide, while the feedstock is mixed with hydrogen-containing gas and hydrogen, subjected to preheating in recuperative heat exchangers and preliminary catalytic hydrogenation in a catalytic reactor moreover, in the second of two series-connected reactors, catalytic hydrodearomatization of the hydrogenate coming from the first of two series-connected reactors is provided ...

Thus, the use of an additional reactor increases the depth of diesel fuel purification while expanding the range of catalysts used for the most efficient removal of specific types of impurities.

It is useful to make an additional reactor and the first of the two series-connected reactors to be made two-section along the catalyst bed, and hydrogenation catalysts are loaded into each section of the additional reactor (upper section A and lower section B) and the first of two reactors connected in series (upper section C and lower section D) various brands with individual catalytic properties.

It is advisable that the catalyst in the upper section A of the additional reactor ensures the purification of the feedstock from various organometallic impurities, in particular compounds of arsenic, sodium, nickel, vanadium and others, which protects the catalysts of the subsequent two series-connected reactors from poisoning with catalytic poisons and increases their service life.

It is advisable that the catalyst in the lower section B of the additional reactor ensures the purification of the feed from impurities of diolefin and acetylenic hydrocarbons, which will ensure the targeted implementation of hydrodesulfurization and hydrodearomatization reactions in the subsequent two reactors connected in series.

It is also advisable that the catalyst in the upper section C of the first of the two reactors connected in series provides hydrocarboxylation, hydrodeoxygenation and hydrodesulfurization of easily removable sulfur compounds.

It is also advantageous that the catalyst in the lower section D of the first of the two reactors connected in series provides hydro-saturation of bicyclic, tricyclic and partially monocyclic aromatic hydrocarbons with partial hydrodearomatization of the feedstock.

It is expedient to use a catalyst with the function of deep hydro-saturation of polycyclic aromatic hydrocarbons, hydrodenitrification and hydrodesulfurization of hard-to-remove sulfur compounds in the second of two series-connected reactors.

Thus, in three reactors, five individual catalytic zones are formed with their own individual catalyst, which ensures the course of certain reactions of diesel fuel hydrotreating.

It is useful to supply hydrogen-containing gas as quenching to the first of two series-connected reactors in the space between sections C and D and / or to the inlet of the second of two series-connected reactors, which will reduce the process temperature, preventing overheating of the catalyst and increasing its service life.

It is expedient to supply the purified hydrogenated product as a heat carrier to the recuperative heat exchangers after the second of two series-connected reactors and the residue from the fractionation column of the fractionation system as the most energy-intensive process streams.

The figure shows a schematic diagram of a diesel fuel hydrofining unit for implementing the proposed method using the following designations:

1-9, 11-19, 21-29, 31-32 - pipelines;

10 - additional reactor;

20 - tubular furnace;

30 - the first reactor;

40 - second reactor;

50, 60, 120 - recuperative heat exchanger;

70 - hot separator;

80 - air cooler;

90 - cold separator;

100 - compressor;

110 - absorption column;

130 - rectification column;

140 - water cooler.

Feedstock, for example, in the form of straight-run diesel fuel together with fresh hydrogen supplied through pipeline 2 and recycle hydrogen-containing gas (hereinafter HSG) supplied through pipeline 3, at a pressure of 60 bar, a temperature of 160 ° C, a circulation ratio of HSG 360 nm3 / m3 is sent sequentially through pipelines 1 and 4 to recuperative heat exchangers 120 and 60, respectively, where it is heated to a temperature of 316 ° C due to the heat of the waste products: hydrotreated diesel fuel removed as a residue through pipeline 15 from the bottom of the rectification column 130, and purified hydrogenate withdrawn through line 9 from the bottom of the second reactor 40, respectively.

Through pipeline 5, the heated reaction mixture enters an additional reactor 10 and flows downward through the catalyst in sections A and B. In the upper section A, solid particles (dust) and organometallic compounds are removed from impurities, in particular compounds of arsenic, sodium, nickel, vanadium and others, in the lower section B, due to catalytic hydrogenation, purification from impurities of diolefin and acetylenic hydrocarbons is provided. After the additional reactor 10, the reaction products are heated through line 6 in a tube furnace 20 to a temperature of up to 370 ° C and through line 7 are fed to the first reactor 30. The reaction mixture in the first reactor 30 passes downwardly through the catalyst in the upper section C, where, due to the flow exothermic reactions of hydrocarboxylation, hydrodeoxygenation and hydrodesulfurization of easily removable sulfur compounds is heated to a temperature of 400 ° C and cooled to 375 ° C by injecting HSG in an amount of up to 37 nm ³ / m ³ through pipeline 27.

Then, on the catalyst in the lower section D of the first reactor 30, the reaction mixture is heated to a temperature of 403 ° C due to exothermic reactions of hydrosaturation of bicyclic, tricyclic and partially monocyclic aromatic hydrocarbons.

The hydrogenated product, after leaving the bottom of the first reactor 30, is cooled in a transfer pipe between reactors 30 and 40 due to the injection of recirculating HSG through pipeline 26 in an amount of up to 37 nm ³ / m ³ to a temperature of 38 ° C and enters through pipeline 8 into the second reactor 40 ...

The reaction mixture in the second reactor 40 passes in a downward flow through the catalyst, heating to a temperature of 410 ° C due to the occurrence of exothermic reactions of deep hydrosaturation of polycyclic aromatic hydrocarbons, hydrodenitrification and hydrodesulfurization of difficult-to-remove sulfur compounds.

The purified hydrogenated product from the bottom of the second reactor 40 is cooled, passing through lines 9 and 11, in recuperative heat exchangers 50 and 60, respectively, to a temperature of 204 ° C and enters through line 12 into a hot separator 70, where it is separated into gas and liquid phases. The gas phase from the hot separator 70 flows through the pipeline 18 to the air cooler 80 for cooling to a temperature of 50 ° C and through the pipeline 19 to the cold separator 90 for separation into a gas stream and condensate.

The gas stream with a high content of hydrogen sulfide after the cold separator 90 through the pipeline 21 enters the absorption column 110 for cleaning the HSG from hydrogen sulfide using a regenerated aqueous solution of monoethanolamine supplied through the pipeline 29. From the top of the absorption tower 110 HSG with a low content of hydrogen sulfide (not more than 100 ppm ) through the pipeline 24 is sent to the compressor 100 and, after compression, is recycled through the pipelines 25, 26, 27 and 3. The absorbent saturated with hydrogen sulfide - an aqueous solution of monoethanolamine - from the lower part of the absorption column 110 through the pipeline 28 is sent to the monoethanolamine recovery unit (in the figure not shown).

Condensate from the cold separator 90 through line 22 enters the top of the distillation column 130 as reflux.

The liquid phase after the hot separator 70 through the pipeline 13 enters the heat exchanger 50 for heating to a temperature of 250 ° C due to the heat of the purified hydrogenate leaving the second reactor 40 through the pipeline 9, and is sent through the pipeline 14 for stabilization in the middle part of the distillation column 130. C from the top of the rectification column 130 through the pipeline 23, stabilization gases are taken.

The liquid product - the remainder of the distillation column 130 - is sent for cooling through pipeline 15 to heat exchanger 120 and through pipeline 16 to water cooler 140, where cooling water is supplied and removed through pipelines 31 and 32, respectively, to a temperature of 40 ° C and is sent to the tank farm marketable product through pipeline 17 in the form of hydrotreated diesel fuel.

Thus, the claimed invention solves the problem of developing a method for hydrotreating diesel fuel, providing deep cleaning of the original diesel fuel from organosulfur, aromatic and other undesirable components, as well as increasing the service life of catalysts.

Claims (11)

1. A method for hydrofining diesel fuel, including heating the feedstock in the form of a straight-run fraction of diesel fuel and / or the corresponding fractions of secondary processes and / or their mixture in a tube furnace, mixing it with a hydrogen-containing gas, catalytic hydrodesulfurization of the resulting mixture in two series-connected reactors to obtain purified hydrogenated product and subsequent fractionation of the purified hydrogenated product in a rectification column, purification of a hydrogen-containing gas in an absorption column from hydrogen sulfide, characterized in that the feedstock is mixed with hydrogen-containing gas and hydrogen, subjected to preheating in recuperative heat exchangers and preliminary catalytic hydrogenation in this additional the second of the two series-connected reactors provide catalytic hydrodearomatization of the hydrogenate coming from the first of the two series-connected reactors. 2. The method according to claim 1, characterized in that the additional reactor and the first of the two reactors connected in series are made two-section along the catalyst bed. 3. The method of claim 2, characterized in that each section of the additional reactor (upper section A and lower section B) and the first of two reactors connected in series (upper section C and lower section D) are loaded with hydrogenation catalysts of various brands with individual catalytic properties ... 4. The method according to claim 3, characterized in that the catalyst in the upper section A of the additional reactor provides purification of the feedstock from various organometallic impurities, in particular compounds of arsenic, sodium, nickel, vanadium and others. 5. The method according to claim 3, characterized in that the catalyst in the lower section B of the additional reactor provides for the purification of the feed from impurities of diolefinic and acetylenic hydrocarbons. 6. The method according to claim 3, characterized in that the catalyst in the upper section C of the first of the two reactors connected in series provides hydrocarboxylation, hydrodeoxygenation and hydrodesulfurization of easily removable sulfur compounds. 7. The method according to claim 3, characterized in that the catalyst in the lower section D of the first of the two series-connected reactors provides for the hydro-saturation of bicyclic, tricyclic and partially monocyclic aromatic hydrocarbons with partial hydrodearomatization of the feedstock. 8. The method according to claim 1, characterized in that the second of the two reactors connected in series uses a catalyst with the function of deep hydrosaturation of polycyclic aromatic hydrocarbons, hydrodenitrification and hydrodesulfurization of hard-to-remove sulfur compounds. 9. The method according to claim. 3, characterized in that in the first of the two series-connected reactors in the space between sections C and D, hydrogen-containing gas is fed as quenching. 10. A method according to claim 1, characterized in that a hydrogen-containing gas is fed as quenching to the inlet of the second of the two reactors connected in series. 11. The method according to claim 1, characterized in that the purified hydrogenated product is fed into the recuperative heat exchangers as a heat carrier after the second of the two reactors connected in series and the residue from the rectification column.

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