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INVENTION
Patent of the Russian Federation RU2134287
A METHOD FOR CLEANING THE CATALYTIC CRAKING PETROL
The name of the inventor: Knyazkov AL; N. Lagutenko; Esipko EA; Khvostenko NN; Broytman AZ; Nikitin A.A.
The name of the patent holder: Open Joint-Stock Company Slavneft-Yaroslavnefteorgsintez
Address for correspondence: 150000, Yaroslavl, Slavneft-Yaroslavnefteorgsintez OJSC, technical department, chief technologist Broitman AZ
Date of commencement of the patent: 1997.05.28
The invention relates to chemical technology, in particular to methods for hydrotreating gasoline fractions, and can be used in the petroleum refining and petrochemical industries. In accordance with the claimed method, a heavy unstable gasoline fraction of catalytic cracking is subjected to hydrodesulfurization followed by its return after hydrodesulfurization to the distillation column of the catalytic cracking unit and stabilizing it together with the non-hydrotreated light gasoline fraction. The invention solves the problem of reducing the sulfur content of gasolines produced in the catalytic cracking process without reducing their octane numbers and reducing the content of olefinic hydrocarbons therein.
DESCRIPTION OF THE INVENTION
The invention relates to chemical technology, in particular to methods for hydrotreating gasoline fractions, and can be used in the petroleum refining and petrochemical industries.
The process of hydrotreating gasoline of secondary origin - catalytic cracking, coking, thermal cracking, visbreaking, etc. - is becoming increasingly important in the scheme for obtaining gasolines, and the role of these processes will increase steadily with the deepening of oil refining. This process is especially relevant in the case of catalytic cracking gasoline, which is one of the main multi-tonnage components of gasoline and determines the consumer properties of the latter at most refineries.
Catalytic cracking gasoline is characterized by a high content of aromatic hydrocarbons (20-30% and more) and olefins (16-40%). In cases where non-hydrotreated feedstock is processed in catalytic cracking plants, the high content of sulfur compounds in the resulting gasoline fractions (0.25-0.35% by weight and more) makes their use difficult for the preparation of marketable gasolines.
Analysis of the structural group composition of gasoline catalytic cracking showed that:
- virtually all olefinic hydrocarbons are in fractions boiling up to 120 ° C;
- in heavy fractions boiling above the temperature of 120 ° C, the main amount of aromatic hydrocarbons (mainly xylenes and xylaxal aromatics) is contained;
- alkane hydrocarbons are represented mainly by isomeric structures;
- the volume ratio of light (NK-120 ° C) and heavy (120 ° C-CK) fractions is close to 1: 1;
- the sulfur content in the fractions boiling up to a temperature of 120 o C is insignificant, with a weighting of the fractional composition it sharply increases (by 3 to 5 times).
Olefinic hydrocarbons in most cases do not affect the oxidative stability of cracked-gasolines. When producing automobile gasolines from these hydrocarbons, which have relatively high anti-knock properties, it is desirable to store in the product. The same applies to aromatic hydrocarbons.
The process of hydrotreatment of catalytic cracking gasolines is technologically more complex than hydrotreatment of straight-run gasoline fractions, since it should not undergo hydrogenation reactions of olefinic hydrocarbons with simultaneous maximum removal of sulfur compounds.
One of the most important factors determining the efficiency of the hydrotreating process of gasoline fractions of catalytic cracking is the fractional composition of the raw materials of the hydrotreating process.
By subjecting the organosulfur compounds to purification, only the high-boiling portion of the catalytic cracking gasoline fraction, which does not contain olefinic hydrocarbons, significantly increases the desulfurization depth, since hydrotreating can be carried out under more stringent conditions. In this case, due to the small content of unsaturated hydrocarbons, there is a slight temperature drop at the inlet and outlet of the reactor and no octane number (OCH) falls.
A method for improving the quality of a gasoline fraction of a catalytic cracking process boiling above a temperature of 165 ° C and containing 0.01-2.5 weight percent sulfur and more than 5 weight percent olefinic hydrocarbons is known, by hydrodesulfurizing it in the presence of an oxide-sulfide catalyst in the atmosphere Hydrogen at elevated temperature and pressure. A product with a low sulfur content is obtained.
A disadvantage of the known method is the low octane number of the hydrotreated gasoline fraction (US 5397455 A, February 14, 1995).
A method for the hydrotreating of catalytic cracking gasoline is known, according to which the gasoline fraction of 45-195 ° C obtained from a catalytic cracking unit (octane number 80.6 ppm, content, wt.% Sulfur: 0.094, aromatic hydrocarbons: 23.5 ) Were subjected to purification in the presence of hydrogen and an alumo-cobalt-molybdenum catalyst at a reactor inlet temperature of 240-300 ° C, a pressure of 3.3 MPa, a feed rate of 4.5 h -1 (Aladysheva EZ et al. Chemistry and Technology Fuels and oils, 1988, N 3, pp. 34-35).
A disadvantage of the known method is the reduction in the octane number of catalytic cracking gasoline after hydrodesulfurization.
The closest solution to the technical essence and the results achieved is the hydrodesulfurization of the gasoline fraction of the catalytic cracking process in the presence of an oxide-sulfide catalyst at elevated temperature and pressure of a hydrogen-containing gas, according to which a catalytic cracking fraction containing sulfur and olefins is hydrodesulfurized in the presence of a catalyst containing Metals of the 8th and 6th groups of the Periodic Table on an oxide-aluminum support to obtain a product with a reduced sulfur content (US 5391288 A, February 21, 1995).
The disadvantage of the method adopted for the prototype is the low octane number of the hydrotreated product.
The object of the present invention is to reduce the sulfur content of the gasoline produced in the catalytic cracking process without reducing the olefinic hydrocarbon content therein and reducing their octane numbers.
The goal is achieved by a method for purifying catalytic cracking gasoline, according to which a heavy unstable gasoline fraction of catalytic cracking is subjected to hydrodesulfurization, followed by its return after hydrodesulfurization to the distillation column of the catalytic cracking and stabilization unit together with the non-hydrotreated light gasoline fraction. On the main distillation column of the fractionating unit of the catalytic cracking unit, the cracking products are separated into a wide gasoline fraction of NK-205 ° C (containing 0.2-0.3% by weight of sulfur in the case where the feedstock is not hydrodesulfurized) and gas oil fractions. To regulate the temperature of the distillation column, 4 circulation irrigation are used. The first (upper) circulation irrigation - heavy gasoline (NK = 120-140 o C, KK = 200-230 o C, sulfur content 0.4-0.9 mass%, depending on its content in the feed) is pumped through the apparatus Air cooling and returned to the column, and the balance amount from the pump discharge goes to the receipt of the feed pumps of the hydrotreatment unit for mixing with the hydrogen-containing gas.
The mixture of raw materials and hydrogen-containing gas (HSG) is heated to a temperature of 250-330 ° C and fed to the reactor, where hydrogenation purification of raw materials from sulfur-containing compounds takes place in the presence of an oxide-sulfide catalyst at a pressure of 2.8-4.5 MPa. From the reactor, the gas product mixture is cooled and fed to a separator to separate the HAS from the unstable hydrogenate, which is sent to a stripping column for degassing the hydrogenate with partial removal of moisture, hydrocarbon gases and hydrogen sulphide.
The hydrotreated heavy gasoline fraction from the stripping column is cooled and returned to the pump of the upper circulating reflux pump of the distillation column of the catalytic cracking unit. The wide gasoline fraction emitted on this column is an unstable mixture of a non-hydrotreated light gasoline fraction of NK-120 (140) ° C and a hydrotreated heavy gasoline fraction of 120 (140) ° C -CK and after stabilization contains 0.1-0.15% . % Of sulfur, while its OCH does not decrease in comparison with the OC of a wide gasoline fraction not subjected to hydrodesulfurization.
Thus, during the hydrotreating of gasoline fractions of catalytic cracking with a high sulfur content and olefinic hydrocarbons with a preliminary distillation of low boiling gasoline fractions, stable benzene with a reduced sulfur content after mixing is obtained without lowering the octane number.
An essential feature of the proposed method is that a heavy unstable gasoline fraction of catalytic cracking is subjected to hydrodesulfurization followed by its return after hydrodesulfurization to the distillation column of the catalytic cracking unit and stabilizing it together with the non-hydrotreated light gasoline fraction.
Thus, the claimed method corresponds to the criterion of the invention "novelty".
Analysis of the known technical solutions for the methods for purifying gasoline fractions of catalytic cracking allows us to conclude that there are no signs in them that are similar to the essential distinctive features of the claimed method, i.e., the conformity of the claimed method with the requirements of the inventive level.
The essence of the proposed method is as follows. On the main fractionator of the fractionating unit of the catalytic cracking unit, cracking products are separated into a wide gasoline fraction of NK-205 ° C (containing 0.2-0.3% by weight of sulfur in the case that the feedstock is not hydrodesulfurized) and gas oil fractions. To regulate the temperature of the distillation column, four circulation irrigation are used on the plates. The first (upper) circulation irrigation is heavy gasoline (NK = 120-140 ° C, KK = 200-230 ° C, sulfur content 0.4-0.9% by weight) - from the 24th plate pump is pumped through an air Cooling and served on the 26th plate. The balance quantity of heavy gasoline from the pump discharge of the first circulating reflux pump of the distillation column is discharged to the direct feed tank of the hydrotreating unit, which acts as a buffer, and the settler from the emulsified water. Heavy gasoline in the tank is under a nitrogen "cushion", which excludes its contact with air oxygen, and through the filters enters the intake of the raw pumps of the hydrotreatment unit for mixing with hydrogen-containing gas
The mixture of raw material and hydrogen-containing gas (WASH) is heated in a heat exchanger and furnace, from where the gas-raw mixture heated to a temperature of 250-330 ° C is fed to the reactor, where in the presence of an oxide-sulfide catalyst at a pressure of 2.8-4.5 MPa, a hydrogenation Purification of raw materials from sulfur-containing compounds.
From the reactor, the gas product mixture is sent to a heat exchanger where, through heat exchange with the gas-raw mixture, it is cooled in the refrigerator and enters the separator to separate the gas product mixture into a WASH and unstable hydrogenate. Unstable hydrogenate from the separator passes through the tube space of the heat exchanger and is sent to a stripping column where degassing of the hydrogenate with partial removal of moisture, hydrocarbon gases and hydrogen sulphide occurs.
The hydrotreated heavy gasoline fraction from the stripping column is cooled in the tube space of the heat exchanger and the cooler to a temperature of 40 ° -45 ° C. and returned to the pump of the upper circulating reflux pump of the catalytic cracking unit distillation column. The wide gasoline fraction emitted on this column is an unstable mixture of a non-hydrotreated light gasoline fraction of NK-120 (140 ° C) and a hydrotreated heavy gasoline fraction of 120 (140) ° C -CK, and after stabilization it contains 0.1-0.15 By weight of sulfur with a preserved octane number.
The advantages of the proposed method are illustrated by the following examples.
Example 1 . Distillate of vacuum distillation of fuel oil. 350-500 ° C, which has not undergone preliminary hydrotreatment, is subjected to catalytic cracking in the presence of a microspheroidal zeolite-containing catalyst DA-250. The main distillation column of the fractionating unit of the catalytic cracking unit separates the cracked products into a wide gasoline fraction of NK-205 ° C (containing 0.26% by weight of sulfur before the hydrotreating unit is included) and gas oil fractions. To regulate the temperature of the distillation column, four circulation irrigation are used on the plates. The first circulation irrigation is heavy gasoline (ff 115-235 o C, content, wt.% Sulfur 0.63, aromatics 55.1, olefins 2.0, iodine number 3.4 g / 100 g, OH mm 73.5) from the 24th plate with a pump is pumped through the air-cooling unit and fed to the 26th plate.
The balance quantity of heavy gasoline from the pump discharge of the first circulating reflux pump is withdrawn to the direct feed tank of the hydrotreatment unit, from where it passes through the filters to the receiving of the feed pumps of the hydrotreatment unit and is supplied for mixing with the hydrogen-containing gas.
The mixture of gasoline and hydrogen-containing gas (HSG) is heated in a heat exchanger and a furnace, from where a gas-raw mixture heated to a temperature of 250 ° C is fed to the reactor, where in the presence of an industrial alumo-cobalt-molybdenum catalyst KGM-70 at a pressure of 2.8 MPa, hydrogenation purification of raw materials from sulfur-containing Compounds (temperature difference in the reactor is 6 o C).
From the reactor, the gas mixture is sent to the heat exchanger, where, due to heat exchange with the gas-containing mixture, it is cooled in the refrigerator to a temperature of 45 ° C and enters the separator to separate the gas product mixture into the FGS and unstable hydrogenate.
The unstable hydrogenate from the separator passes through the tube space of the heat exchanger and is sent to a stripping column where, at a pressure of 0.72 kgf / cm 2 and a bottom temperature of 180 ° C, hydrogenation is degassed with partial removal of moisture, hydrocarbon gases and hydrogen sulphide.
The hydrotreated heavy gasoline fraction (content, wt%: sulfur 0.10, aromatics 54.7, olefins 0.6, iodine number 1.6 g / 100 g, rms m. 72.4) from the stripping column is cooled in The tube space of the heat exchanger and the refrigerator to a temperature of 45 ° C and returns to the pump of the upper circulating reflux pump of the distillation column of the catalytic cracking unit. The wide gasoline fraction emitted on this column is an unstable mixture of a non-hydrotreated light gasoline fraction of NK-115 ° C and a hydrotreated heavy gasoline fraction of 115 ° C -CK, after stabilization contains, by weight: 0.15 sulfur, aromatics 25.1 , Olefins of 2.6 and has an RP = 79.5 points (MM).
Example 2 . On the main distillation column of the fractionating unit of the catalytic cracking unit, the cracking products obtained according to Example 1 are separated into a wide gasoline fraction of NK-205 ° C (containing 0.29% by weight of sulfur prior to inclusion of the hydrotreating unit) and gas oil fractions. The first circulation irrigation is heavy gasoline (f. 120-230 ° C, content, wt.%: Sulfur 0.89, aromatics 56.3, olefins 3.6, iodine number 4.2 g / 100 g, OH mm 74.2 points) from the 24th plate by the pump is pumped through the air-cooling unit and fed to the 26th plate.
The balance amount of heavy gasoline from the pump discharge of the first circulating reflux pump is withdrawn to the direct feed tank of the hydrotreatment unit and then passes through filters to the feed pumps of the hydrotreatment unit for mixing with hydrogen-containing gas.
The mixture of raw materials and hydrogen-containing gas (HSG) is heated in a heat exchanger and furnace, from where a gas-raw mixture heated to a temperature of 300 ° C is fed to the reactor, where in the presence of an industrial aluminocobalt-molybdenum catalyst GO-70 at a pressure of 4.5 MPa, hydrogenation purification of raw materials from sulfur-containing (Temperature drop in the reactor is 9 ° C).
From the reactor, the gas product mixture is sent to a heat exchanger where, through heat exchange with the gas-raw mixture, it is cooled in the refrigerator and enters the separator to separate the gas product mixture into a WASH and unstable hydrogenate. The unstable hydrogenate from the separator passes through the tube space of the heat exchanger and is sent to a stripping column where, at a pressure of 0.72 kgf / cm 2 and a bottom temperature of 180 ° C, hydrogenation is degassed with partial removal of moisture, hydrocarbon gases and hydrogen sulphide.
The hydrotreated heavy gasoline fraction from the stripping column (content, wt.%: Sulfur 0.06, aromatics 54.9, olefins 0.9, iodine number 0.6 g / 100 g, MP 72.8 ppm) is cooled In the tube space of the heat exchanger and the refrigerator and returns to the pump of the upper circulating reflux pump of the distillation column of the catalytic cracking unit. The wide gasoline fraction emitted on this column is an unstable mixture of a non-hydrotreated light gasoline fraction of NK-120 ° C and a hydrotreated heavy gasoline fraction of 120 ° C -CK, after stabilization contains, %: Sulfur, 0.10, aromatics 26.1, olefins 24.8 and has an RR = 79.7 ppm (MM).
Example 3 . Distillate of vacuum distillation of fuel oil. 350-500 ° C., which has not undergone a preliminary hydrotreatment, is subjected to catalytic cracking according to Example 1.
On the main distillation column of the fractionating block of the catalytic cracking unit, the cracking products are separated into a wide gasoline fraction of NK-205 ° C (content, wt.% Of sulfur: 0.26, aromatics 25.3, olefins 24.8, iodine number 64.7 g / 100 g, rms m. 79.6 points) and gas oil fractions. A wide gasoline fraction is sent to compounding for the preparation of gasoline.
Example 4 . Distillate of vacuum distillation of fuel oil. 350-500 ° C., which has not undergone a preliminary hydrotreatment, is subjected to catalytic cracking according to Example 1.
On the main distillation column of the fractionating unit of the catalytic cracking unit, the cracking products are separated into a wide gasoline fraction of NK-205 ° C and gas oil fractions. The wide gasoline fraction (content, wt.%: Sulfur 0.28, aromatics 25.3, olefins 24.8, iodine value 64.7 g / 100 g and GH = 79.5 ppm (m) are sent to the unit Hydrotreating catalyst, where in the presence of an industrial aluminum-cobalt-molybdenum catalyst GO-70 at a pressure of 3.3 MPa and a temperature of 300 ° C., its hydrogenation purification from sulfur-containing compounds occurs.The temperature difference in the reactor as a result of the hydrogenation reaction of olefinic hydrocarbons exceeds 60 ° C. Hydroprocessed wide gasoline Fraction containing, by weight: sulfur 0.08, aromatics 26.1, olefins 12.7 and having an RP = 73.0 ppm (MM).
Thus, during the hydrotreatment of gasoline fractions of catalytic cracking with a high sulfur content and olefinic hydrocarbons with a preliminary distillation of low boiling gasoline fractions, stable gasoline with a sulfur content of 0.1 to 0.15 mass% is obtained after mixing without lowering the octane number (Examples 1 and 2 ). The non-hydrotreated broad gasoline fraction of catalytic cracking has a high sulfur content, which makes it difficult to compound for commercial gasolines (Example 3), and its hydrotreating leads to a significant drop in the octane number.
CLAIM
A method for hydrodesulfurizing a gasoline fraction of catalytic cracking in the presence of an oxide-sulphide catalyst at elevated temperature and pressure of a hydrogen-containing gas, characterized in that a heavy unstable gasoline fraction of catalytic cracking is subjected to hydrodesulfurization followed by its return after hydrodesulfurization to a distillation column of a catalytic cracking unit and stabilizing it together with a non-hydrotreated Light gasoline fraction.
print version
Date of publication 07.04.2007gg
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