JPH0216355B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for hydrocracking heavy oil, and more specifically, a plurality of reaction towers are used, and before the hydrocracked oil from one reaction tower is introduced into the next reaction tower, an intermediate in the hydrocracked oil is The present invention relates to a method for hydrocracking heavy oil that is effective in preventing excessive decomposition of middle distillates and increasing the yield of middle distillates by separating the fractions in advance. Generally, when heavy oil is hydrocracked, it is necessary to carry out the process under harsh conditions. However, when hydrocracking under harsh conditions, heavy oil is overcracked and only the yield of LPG and naphtha increases, resulting in kerosene,
There was a problem that the yield of middle distillates such as light oil was low. On the other hand, there was a problem that under mild conditions, the residual fraction was not sufficiently decomposed and a useful fraction could not be obtained. Therefore, a method of hydrocracking heavy oil in two or more stages has been proposed, but even with this method, the yield of middle distillates cannot be said to be sufficient. Therefore, the present inventor has conducted extensive research in order to overcome the drawbacks of the above-mentioned conventional techniques and to develop a method for hydrocracking heavy oil with a high yield of middle distillates. As a result, in addition to hydrocracking heavy oil using multiple reaction towers, the intermediate distillate in this hydrocracked oil is The inventors have discovered that it is possible to significantly increase the production of middle distillates by separating the fractions and then further hydrocracking the residual oil in the next reaction column, leading to the completion of the present invention. That is, the present invention provides a method for hydrocracking heavy oil in a plurality of reaction towers, in which hydrocracked oil obtained from the reaction towers (excluding the final stage reaction tower) is introduced into a separation tower. More than 75vol% of it is 343℃
The fraction that boils at 343°C or higher is separated into the fraction that boils at 343°C or higher, and 75 vol% or more of that boils at 343°C or higher;
The fraction that boils above 343°C is introduced into the next reaction column, where it is hydrocracked and then introduced into the atmospheric distillation column.On the other hand, the fraction whose 75 vol% or more boils below 343°C is directly introduced into the atmospheric distillation column. Then, the fraction introduced into the atmospheric distillation column is distilled under atmospheric pressure to separate each fraction, and the fraction of which 75 vol% or more boils at 343°C or higher is introduced into the vacuum distillation column. , provides a method for hydrocracking heavy oil, characterized in that a fraction of which 75 vol% or more boils at 525° C. or lower, obtained by vacuum distillation in the vacuum distillation column, is circulated to any of the reaction columns. It is something to do. Regarding heavy oil that is subject to the method of the present invention,
There are no particular restrictions and various types can be mentioned, but in general, it is a heavy oil with a content of components with a boiling point of 343°C or higher at 50% or more, preferably 80% or more, and typical examples include atmospheric distillation residue oil and vacuum distillation residue oil. Other examples include vacuum gas oil, visbreaking oil, tar sand oil, and mixtures thereof. As described above, in the method of the present invention, the hydrogenolysis of heavy oil is carried out in several stages using a plurality of reaction towers.
In this case, the number of reaction columns is not particularly limited as long as it is two or more, and may be determined as appropriate depending on various conditions or desired hydrocracked oil composition. but,
Usually, it is sufficient to use about two or three reaction towers, and more may be used, but using too many reaction towers complicates the operation and is not a good idea. Next, the method of the present invention will be explained in more detail based on the drawings. FIG. 1 is a schematic diagram showing an example of an apparatus used in the method of the present invention, and is an example using two reaction towers.
According to the method of the present invention, first, heavy oil as a raw material is introduced into the first reaction column 1 together with hydrogen. Here, the heavy oil is hydrocracked, and the obtained hydrocracked oil is not immediately introduced into the second reaction tower 2, but is immediately introduced into the separation tower 3. In this separation column 3, the hydrocracked oil is separated into a fraction of which 75 vol% or more has a boiling point of 343°C or lower and a fraction whose boiling point of 75 vol% or more has a boiling point of 343°C or higher. More than 75 vol% of that has a boiling point of 343℃
The above fraction is led to the second reaction column 2, where it is hydrocracked, and then introduced to the atmospheric distillation column 4. On the other hand, the material separated in the separation column 3
The fraction, of which 75 vol% or more has a boiling point of about 343° C. or less, is directly led to the atmospheric distillation column 4. By such operation,
It is possible to effectively prevent the middle distillate in the hydrocracked oil obtained in the first reaction column 1 from becoming lighter due to excessive cracking. Subsequently, the fractions introduced into the atmospheric distillation column 4 are separated into gas and LPG by atmospheric distillation.
75VO1% or more of the boiling point
The fraction having a temperature of 343°C or higher is led to the vacuum distillation column 5.
Vacuum distillation is carried out here, resulting in 75vo1%
The fraction with a boiling point of 525°C or less is transferred to the first reaction column 1 again.
Alternatively, it is circulated to the second reaction tower 2. By circulating to this reaction column, unreacted vacuum gas oil is further hydrocracked, and almost all of it can be recovered as a middle distillate. In the above-mentioned hydrogenolysis reaction, the catalyst, reaction conditions, etc. to be used may be appropriately selected, but the present invention can be achieved more effectively by using the following catalyst and reaction conditions. First, as a catalyst used for hydrocracking heavy oil in a reaction tower, it is preferable to use a catalyst in which a metal from Group 1 to Group 3 of the periodic table is supported on various carriers as an active component. To explain this more specifically, the active ingredients include nickel, cobalt, molybdenum, and tungsten.
Molybdenum or nickel-tungsten combinations are particularly preferably used. On the other hand, alumina-silica, alumina-zeolite or alumina-boria-zeolite is used as the carrier. Examples of alumina-zeolite include X-type, Y-type, hydrogen-type and decationized zeolites, ZSM-type zeolite, and especially ultra-stable crystalline aluminosilicate Y-type zeolite (hereinafter referred to as "US-Y-type zeolite"). ) is preferably used. The composition and properties of this US-Y type zeolite are such that the Na ₂ O content is 0.5% by weight or less, preferably 0.3% by weight or less, and the SiO ₂ /Al ₂ O ₃ ratio is 5 to 150, preferably 6 to 30. , more preferably from 7 to 10. Furthermore, the unit cell size is 23.00 ~
24.60 Å, preferably 24.25 to 24.50 Å. In addition, the specific surface area is 200 m ² /g or more, preferably 400 to 800
m ² /g. In order to produce such US-Y type zeolite, for example, synthetic haujasite is used as a raw material, which is exchanged with NH ₄ +, washed with water, dried, further calcined or steam treated, and finally treated with ammonium salt or amine. A method such as treating with salt and then firing (Japanese Patent Publication No. 8129/1983) may be used. Such US-
The composition of the alumina-zeolite as a carrier using Y-type zeolite as the zeolite is not particularly limited, but usually US-Y-type zeolite is used in an amount of 20 to 80% by weight, preferably 40 to 60% by weight based on the total alumina-zeolite. % should be included. The composition of the alumina-boria-zeolite is 15 _to 55 wt% alumina, preferably 20 to 50 wt%, and 5 to 25 wt% boria as _B2O3 , preferably 10 to 20 wt%.
%, zeolite is 20~80wt%, preferably 30~
It is 70wt%. Catalysts with such properties can be produced by various methods, and representative methods include the following methods. In other words, alumina or alumina-boria as a matrix is prepared by neutralizing aluminate or aluminum salt by adding acid or alkali to prepare amorphous alumina hydrate having a concentration of 5 wt% or more. Japanese product PH
It is produced by heating to 50°C or higher while stirring in a weakly alkaline solution of 8 to 12°C. This is kneaded and dispersed with silica or zeolite to obtain a carrier, on which a group - group metal of the periodic table is supported by a known method. If the hydrocracking of the present invention is carried out using the catalyst obtained by the above-described treatment, the hydrocracking of heavy oil will proceed under relatively mild conditions. The reaction conditions in the reaction towers at this time are generally more severe as the reaction towers in the later stages are more severe than the reaction towers in the earlier stage, but in any case, the conditions in each reaction tower are such that the reaction temperature is 300 to 500. ℃, preferably 350 ~
450℃, reaction pressure 50-250Kg/cm ² , preferably 100
~200Kg/ ^cm2 , supply hydrogen/oil ratio 500~ ^3000Nm3 /
Kl, preferably 70 to 2000Nm ³ /Kl, liquid hourly space velocity
It may be determined as appropriate within the range of 0.1 to 3.0 hr ^-1 , preferably 0.2 to 1.0 hr ^-1 , and the supplied hydrogen concentration is 75 mol% or more, preferably 85 mol% or more. In addition, the separation operation in the separation column 3 is performed to determine the volume of the fraction above 343°C in the gas stream exiting from the top of the separation tower 3 and the volume of the fraction below 343°C in the liquid stream exiting from the bottom of the separation tower 3. The conditions are such that the sum with the volume ratio of is the smallest. In other words, in the overhead fraction, the boiling point
It is necessary that the fraction with a boiling point of 343°C or higher is contained in an amount of 75vo1% or more, and the bottom distillate contains a fraction with a boiling point of 343°C or higher in an amount of 75vo1% or more. usually,
Operating conditions are temperature 250~500℃, preferably 320~
450℃, pressure 50~250Kg/ ^cm2G , preferably 100~
It should be 200Kg/cm ² G. Note that the separation tower 3 may be provided between each reaction tower (in this case, the number of separation towers will be one less than the number of reaction towers), but only one separation tower 3 will be provided between each reaction tower. All of the hydrocracked oil may be directed centrally. Furthermore, the conditions within the atmospheric distillation column 4 may be determined as appropriate and are not particularly limited. Conditions commonly used are sufficient. The internal conditions in the vacuum distillation column 5 are also not limited and may be determined according to various conditions, but generally the temperature is 300 to 450°C, preferably 360 to 450°C.
The temperature is 400°C and the pressure is 50 mmHg or less, preferably 35 mmHg or less. According to the method of the present invention as described above, over-cracking of middle distillates does not occur, and high-boiling fractions are subjected to operations such as vacuum distillation and re-hydrocracking, so that especially kerosene, gas oil, etc. The yield is significantly higher. Therefore, the method of the present invention is extremely effective in practice as a method for efficiently obtaining high value-added middle distillates from inferior heavy oil. Next, examples of the present invention will be shown together with reference examples and comparative examples. Reference example (Catalyst preparation) A 50% aqueous glyconic acid solution was added to a sodium aluminate solution with a concentration of 5.0 wt% as Al ₂ O ₃ , and then
An aluminum sulfate solution with a concentration of 2.5 wt% as Al ₂ O ₃ was added to obtain a slurry with a pH of 7.0. This slurry was filtered and washed with 0.2 wt% ammonia water to prepare a pseudo-boehmite-containing alumina hydrate. Further, the molar ratio of SiO ₂ /Al ₂ O ₃ is 8.5,
Contains 0.2wt% alkali metal as _Na2O ,
It has a crystal lattice constant of 24.35 Å, and the specific surface area when fired at a temperature of 740°C for 2 hours is 620 Å.
m ² /g US-Y type zeolite was prepared. The above alumina hydrate and US-Y type zeolite are mixed, heated and concentrated in a kneader, formed into pellets, dried in air at 110°C for 16 hours, and then calcined at 550°C for 3 hours to form US-Y type zeolite. A 50wt% catalyst support was obtained. This carrier was impregnated with an aqueous solution containing ammonium paratungstate and nickel nitrate, and then dried while gradually increasing the temperature to 250°C.
Next, by firing at 550°C for 2 hours, the amount of supported tungsten and the amount of nickel supported were 13.3 wt%, respectively.
A catalyst with a concentration of 4.1 wt% was produced. Example 1 Using the apparatus shown in FIG. 1, the first reaction tower 1 and the second reaction tower 2 were filled with the catalyst prepared in the above reference example. In such equipment, Kuwait atmospheric distillation residue oil (specific gravity 0.965,
Distillate with boiling point of 343℃ or above 92vo1%, viscosity 400cst (50
°C), sulfur content 3.9wt%, residual carbon 10.6wt%, nitrogen content
2380ppm, vanadium content 46ppm, nickel content
16 ppm) was introduced into the first reaction column 1, where the reaction pressure was 150 Kg/cm ² G, the reaction temperature was 400°C, and the hydrogen/oil ratio was
2000Nm ³ /Kl, liquid hourly space velocity (LHSV) 0.6hr ^-1 ,
Hydrogenolysis was performed at a hydrogen concentration of 90 mol%. Next, the hydrocracked oil coming out of the first reaction tower 1 is sent to the separation tower 3, where 80 vol% or more of it boils at 343°C or lower and 80 vol% or more of it boils at 343°C.
It was separated into a boiling fraction (). The operating conditions in this separation column 3 are a temperature of 400℃ and a pressure of 145Kg/cm ²
And so. Subsequently, the fraction (2) separated in the separation column 3 was immediately sent to the atmospheric distillation column 4 without being sent to the second reaction column 2. On the other hand, the fraction () is led to the second reaction tower 2, where the reaction pressure is 145Kg/cm ² , the reaction temperature is 410°C, and the hydrogen/oil ratio is 2000Nm ³ /Kl, LHSV
Hydrocracking treatment was carried out under conditions of 0.6 hr ^-1 and a hydrogen concentration of 90 mol %, and then introduced into the atmospheric distillation column 4. In the atmospheric distillation column 4 into which the fraction ( ) and the hydrocracked fraction ( (naphtha), a fraction with a boiling point of 171 to 250°C (kerosene), a fraction with a boiling point of 250 to 343°C (gas oil), and an atmospheric distillation residue (boiling point of 343°C or higher). The atmospheric distillation residue obtained here is led to the vacuum distillation column 5, where 80 vol% or more of it boils at 525°C or lower (vacuum gas oil) and 80 vol% or more of it boils at about 525°C or higher. It was separated into a fraction (vacuum residue). Note that the operating conditions in the vacuum distillation column 5 are 390°C;
It was set at 15mmHg. Further, the entire fraction (2) obtained here was introduced into the second reaction tower 2 and subjected to hydrocracking treatment. The composition of the entire oil after hydrocracking in the above operation is shown in Table 1. Comparative Example 1 Using the apparatus shown in Fig. 2 (no separation column is provided compared to the apparatus shown in Fig. 1), the first reaction column 1
Hydrocracking was carried out under the same conditions as in Example 1, except that the entire amount of the hydrocracked oil obtained from the above was introduced into the second reaction column. The overall composition of the oil after hydrocracking is shown in Table 1. Comparative Example 2 Using the apparatus shown in Figure 3 (which is not equipped with a vacuum distillation column compared to the apparatus shown in Figure 1), the atmospheric distillation residue from the atmospheric distillation column 4 was not introduced to the vacuum distillation column. Hydrocracking was carried out under the same conditions as in Example 1, except that the mixture was taken out of the system. The overall composition of the oil after hydrocracking is shown in Table 1. Comparative Example 3 Using the apparatus shown in Fig. 4 (which is not equipped with a separation column and a vacuum distillation column compared to the apparatus shown in Fig. 1), the entire amount of hydrocracked oil from the first reaction column 1 was transferred to the second reaction column. The hydrocracked oil obtained here was introduced into the reaction column 2, and the resulting hydrocracked oil was introduced into the atmospheric distillation column 4 to be separated into each fraction, and the atmospheric distillation residue was taken out of the system. At this time, the raw material heavy oil, the catalyst, the reaction conditions of the first and second reaction towers, etc. were all the same as in Example 1. The overall composition of the oil obtained after hydrocracking is shown in Table 1. Example 2 In a reference example, a commercially available Y-type zeolite was used instead of the US-Y-type zeolite, and a catalyst was prepared under the same conditions as in the reference example except for the use of a commercially available Y-type zeolite. Subsequently, using this catalyst, hydrogenolysis was carried out under the same conditions as in Example 1 except for the following conditions. The overall composition of the oil after hydrocracking is shown in Table 1. Comparative Example 4 Except for using the catalyst used in Example 2,
Hydrogenolysis was carried out under the same conditions as in Comparative Example 1.
The overall composition of the oil after hydrocracking is shown in Table 1.

[Table] (Note) The numbers in the table indicate the ratio of each fraction to the raw oil.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus used in the method of the present invention, and FIGS. 2 to 4 are schematic diagrams showing apparatuses used in Comparative Examples 1 to 3, respectively. 1...First reaction tower, 2...Second reaction tower, 3...
Separation column, 4...Normal pressure distillation column, 5...Reduced pressure distillation column.

Claims (1)

[Scope of Claims] 1. In a method of hydrocracking heavy oil using a plurality of reaction towers, the reaction tower (excluding the final stage reaction tower)
The hydrocracked oil obtained from the hydrocracked oil is introduced into a separation column, and the fraction of which 75 vol% or more boils below 343°C and its
It is separated into a fraction in which 75 vol% or more boils at 343°C or higher, and the fraction whose 75 vol% or more boils at 343°C or higher is introduced into the next reaction column for hydrogenolysis and then introduced into the atmospheric distillation column. On the other hand, the fraction of which 75 vol% or more boils below 343°C is directly introduced into the atmospheric distillation column, and then the fraction introduced into the atmospheric distillation column is distilled under atmospheric pressure to be fractionated into each fraction. , more than 75vol% of which is 343℃
The fraction boiling above is introduced into a vacuum distillation column, and the fraction obtained by vacuum distillation in the vacuum distillation column, of which 75 vol% or more boils at 525°C or below, is circulated to any of the reaction columns. Features of heavy oil hydrocracking method. 2. The method according to claim 1, in which heavy oil is hydrocracked in two reaction towers.