JP3187547B2 - Pyrolysis of heavy oil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing high value-added gasoline and diesel fractions by pyrolyzing heavy oils, particularly petroleum heavy oils, and for producing fuel residual oils.

[0002]

BACKGROUND OF THE INVENTION Various methods have been proposed for converting heavy oils into useful light fractions, such as higher value added gasoline and diesel fractions. There is a process that uses a catalyst and hydrogen in the processing of heavy oil, but economical due to the deterioration of the catalyst due to heavy metals and asphaltenes contained in heavy oil in large amounts, the use of expensive hydrogen, and a large amount of energy consumption There is a problem. On the other hand, the thermal decomposition method is widely used because it does not use a catalyst and hydrogen and thus has a low processing cost.

[0003] As a pyrolysis reforming method, a delayed carbonization method (Hydrocarbon Processing Vol. 69, No.
11, November 1990; 105) and the visbreaking method (Hydrocarbon Processing Vol. 69, No. 1)
1, November 1990, p. 104) are well known.

[0004] The delayed coking method is a method of obtaining solid coke as a product, so that a combustible residual oil cannot be obtained. In order to obtain residual oil that can be burned by conventional fuel oil combustion equipment, it can only be handled by the visbreaking method.

[0005] However, in the visbreaking method, when the conversion is increased to a certain degree or more, the stability of the pyrolysis residue is lost, asphaltene agglomerates and separates, and not only sludge is generated in the residue but also sludge is generated. Since coking occurs and the operation of the stable apparatus cannot be continued, the conversion rate, which is indicated by the percentage of generated light components, is extremely low.
Stays at -30%.

As a thermal cracking method for obtaining a conversion rate higher than the visbreaking method and a thermal cracking residue applicable to general fuel oils, JP-A-57-119986 and JP-A-57-2076 are known.
87, JP-A-58-5390, JP-B-62-5975
3, and DD-AP201804, 202446, 20
7923 and 208313, a new method is proposed.

[0007] According to this novel method, a remarkable improvement in the conversion rate is recognized, but the conversion product distribution is such that the ratio of the heavy gas oil fraction is high and the ratio of the higher value-added gasoline and diesel fractions is low. There's a problem.

[0008] The present and future demand for converting crude oil to higher value-added products has been unsatisfactory for refiners, requiring significant improvements in conversion rates in the processing of heavy oils. There are many demands for high gasoline and diesel oil product acquisition rates.

[0009]

SUMMARY OF THE INVENTION In the thermal cracking method of heavy oil, the conversion rate of gasoline and diesel fraction is higher at a higher conversion rate than the visbreaking method, and the thermal cracking residual oil after removing light products is obtained. Provides a pyrolysis method that can be burned by general combustion equipment.

[0010]

According to the method of the present invention for cracking heavy oil, the pressure is adjusted to 5 to 20 kg / cm by pressure adjusting means.
Heavy oil is introduced into the tube of the externally heated tube heating furnace adjusted to ² G, and the temperature is 480-500 ° C., and the residence time is 30-1.
A first pyrolysis step of obtaining a pyrolysis product under the conditions of 80 seconds; and a pyrolysis product of the first pyrolysis step is largely separated by the pressure adjusting means without separating a heavy fraction therein. After reducing the pressure to about atmospheric pressure, 10 to 2
It is introduced into a multistage bubble reaction tower using steam supplied as a heat source at a temperature of 380 to 430 ° C and a pressure of 0.1 to 1.
Under a condition of 0 kg / cm ² G, residence time of 30 to 120 minutes, and hydrocarbon partial pressure under reduced pressure, it is further thermally decomposed and subjected to steam distillation to separate and obtain a light fraction and a fuel residual oil. And a second pyrolysis step.

The heavy oil used in the present invention includes, as petroleum-based heavy oil, heavy oil crude oil, tar sands, residual oil at normal pressure, residual oil under reduced pressure, and the like. Is a heavy oil other than petroleum.

In the present invention, the raw heavy oil is continuously thermally decomposed in a first-stage tubular heating furnace, and the decomposition product is directly used in a multi-stage bubble reactor using a second-stage stripping steam as a heat source. It is pyrolyzed at the same time as the first
The light fraction produced in the stage and the second stage is distilled together with steam from the multi-stage bubble reactor without being exposed to excessive heat.

The reaction in the first stage is carried out in an externally heated tube furnace under a liquid phase and under pressure.

The most important point of this reaction is to carry out the reaction while obtaining a high conversion rate and at the same time suppressing the formation of coke. Therefore, it is necessary to strictly control the reaction conditions such as temperature, pressure and residence time. The higher the reaction temperature, the higher the conversion, but at the same time, the greater the occurrence of coking, which leads to blockage of the reaction tube. Therefore, in order to suppress the formation of coke, the residence time exposed to a high temperature needs to be controlled to be extremely short. If a low reaction temperature is applied, the residence time can be extended, but the conversion is low and it is not economically feasible.

The reaction conditions that can be selected in such a situation are naturally limited, but the conditions employed in the present invention are as follows:
Pressure 5-20 kg / cm ² G, Reaction temperature 480-500
The residence time at 30C is 30 seconds-180 seconds.

However, since each heavy oil has a temperature and a time at which coking unique to the heavy oil exists, the reaction conditions actually applied must be set to appropriate conditions according to the physical properties of the heavy oil. Selection is necessary to obtain high conversion and to prevent clogging of the reaction tube by coking.

The second stage is carried out in a multi-stage bubble reactor using stripping steam as a heat source under substantially atmospheric pressure (the partial pressure of the starting hydrocarbon is reduced). Coke is more likely to form if normal high-temperature heating is continued to further decompose the products that have undergone thermal decomposition in the first stage. Under these circumstances, the conditions applicable to the second stage are as follows: the decomposition products from the first stage are introduced into the second stage without separation, and the reaction temperature is 380-430 ° C., the pressure is 0.1-1. 0k
g / cm ² G, residence time 30 minutes to 120 minutes, and the amount of steam to be blown in the raw material is 10 to 25 wt%.

A preferred apparatus for performing the second step is
For example, in a vertical cylindrical reactor, 1) a plurality of perforated plates are installed at intervals above and below, 2) droplets adhering to the inner wall of the gas-liquid separation portion of the reactor accumulate and coke. In order to prevent this, a scraper that slides on the inner wall surface of the gas-liquid separation part is provided. 3) Similarly, to prevent the sedimentary carbon particles from being deposited and deposited on the bottom of the reactor, Is provided with an agitator for mixing and discharging the oil to be treated reaching the bottom of the reactor on average.

One embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a flow sheet according to one embodiment of the present invention. 1 is an externally heated tubular heating furnace, 2 is a multistage bubble reactor, 3
Is a feed line for the raw material, 4 is a supply line, 5 is a light oil extraction line, 6 is a residual oil extraction line, 7 is a steam supply line, and 8 is a pressure regulating valve.

The raw material heavy oil is continuously introduced from the raw material feed line 3 into the externally heated tubular heating furnace 1 and has a reaction temperature of 450.
−550 ° C., pressure 5-20 kg / cm ² G, 10 seconds −
It is introduced into the multi-stage bubble reaction tower 2 via the supply line 4 and the pressure regulating valve 8 without heating and thermal decomposition for 2 minutes to separate decomposition products without separation.

Here, the raw oil which has undergone a considerable amount of thermal decomposition in the externally heated tubular heating furnace 1 is further maintained at 380-430 ° C. by introducing steam from the steam supply line 7.
Residence time 30 minutes-120 minutes, pressure 0.1-1.0 kg /
It is further pyrolyzed under the condition of cm ² G.

The generated gas and volatile cracked oil vapor are extracted together with steam from the upper part of the multi-stage bubble reactor 2 and introduced into a fractionation tower (not shown) through a light oil extraction line 5 where gas, It is separated into naphtha, kerosene and light oil fractions.

The liquid pyrolysis residual oil by-produced in the multistage bubble reactor 2 is extracted through a residual oil extraction line 6.

By performing the first stage of the thermal decomposition of heavy oil in the liquid phase and under pressure using the externally heated tubular heating furnace 1, the rate of obtaining gasoline and diesel oil is improved. Thereafter, the conversion rate is further increased by pyrolysis in a multistage bubble reaction tower 2 using stripping steam as a heat source under normal pressure,
The overall gasoline and diesel oil acquisition rate will increase. First
By blowing steam from the lower part of the tower, the light fraction decomposed and generated in the second step and the second step is extracted out of the system without exposing it to unnecessary heat, thereby improving the light fraction acquisition rate.

The residual residual oil is exposed to a violent flow state due to the second stage steam injection, and the generated coke is also finely colloidal and dispersed and stabilized in the residual oil. It becomes a stable residual oil that can be burned at, and continuous operation for a long time without clogging or other occurrences is possible.

[0027]

Example 1 A vacuum residue having the following composition was used as a raw material for thermal decomposition. This was performed according to the process flow shown in FIG. The reaction conditions and the reaction results are shown in Table 1.

Raw material properties (residue under reduced pressure) Specific gravity (SP, Gr) (15/4 ° C.) 1.005 Distillation characteristics (Distillation) Initial boiling point (IBP) 377 ° C. 5 vol. % 498 ° C 10 vol. % 523 ° C 15 vol. % 532 ° C Sulfur (wt.%) 3.30 Nitrogen (wt.%) 0.43 Viscosity (cP) 811 at 100 ° C 52 at 135 ° C Conradson Residual Coal (CCR) (wt.%) 16.65 n-hexane Insolubles ( _n C ₇ Insolv.) (Wt.%) 5.2 Nickel (wt. Ppm) 74 Vanadium (wt. Ppm) 210 Examples 2 to 4 Using the same vacuum residue as in Example 1, The test was performed while changing the temperature conditions of the first and second stages.

The reaction conditions and the reaction results are shown in Table 1.

[0030]

[Table 1] Comparative Example 1 The same raw material as in Example 1 was thermally decomposed by a visbreaking method in an externally heated tubular heating furnace. Pyrolysis is the first of Example 1.
The same reaction conditions as in the steps were used. The reaction conditions and the reaction results are shown in Table 1.

COMPARATIVE EXAMPLE 2 Pyrolysis of the same raw material as in Example 1 was carried out in a multistage bubble reactor according to a conventional method to obtain a conversion rate higher than the visbreaking method and a pyrolysis oil applicable to general fuel oil. Pyrolysis Example 1
The reaction conditions were the same as in the second step. The reaction conditions and the reaction results are shown in Table 1.

The softening point (ring and ball method) of the cracked residual oil of Example 1 and Comparative Example 2 is 90 ° C.

From the results of Examples 1 to 4, the thermal decomposition method of the present invention showed that the conversion rate of the bisbreaker of Comparative Example 1 was 49.5 to 56.5%, which was higher than the conversion rate of 15%, and that the multistage of Comparative Example 2 was Acquisition rate of naphtha and light gas oil (LGO) in bubble reactor 1
An acquisition rate of 22.3 to 25.6% higher than 6.5% was obtained.

[0034]

As explained above, according to the present invention, heavy oil is thermally decomposed in a first stage under pressure in an external combustion type tubular heating furnace.
By adopting a two-stage pyrolysis method in which pyrolysis is performed under atmospheric pressure under steam stripping in a second-stage multistage bubble reaction tower without separating decomposition products, a conversion rate higher than that of the bisbreaker method is achieved. A gasoline / diesel oil acquisition rate can be obtained, and a residual oil that can be generally used as fuel oil can be obtained.

[Brief description of the drawings]

FIG. 1 is a flow sheet of Example 1 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Externally heated tubular heating furnace 2 Multistage bubble reaction tower 3 Raw material feed line 4 Supply line 5 Light oil extraction line 6 Residual oil extraction line 7 Steam supply line 8 Pressure control valve

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-124191 (JP, A) JP-A-63-301295 (JP, A) JP-A-61-12789 (JP, A) JP-A Sho 50- 89402 (JP, A) JP-A-61-261391 (JP, A) JP-A-57-207687 (JP, A) JP-A-59-71389 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) C10G 51/02 C10G 9/00-9/42

Claims (1)

(57) [Claims] 1. A pressure adjusting means for controlling a pressure of 5 to 20 k
Heavy oil is introduced into a tube of an externally heated tubular heating furnace adjusted to g / cm ² G to obtain a pyrolysis product at a temperature of 480 to 500 ° C. and a residence time of 30 to 180 seconds. After the first pyrolysis step and the pyrolysis product of the first pyrolysis step are depressurized to about atmospheric pressure by the pressure adjusting means without separating a heavy fraction therein, the heavy oil For 1
It is introduced into a multi-stage bubble reaction tower using steam supplied as a heat source at a temperature of 380 to 430 ° C. and a pressure of 0.1 to 25 wt%.
１．０1.0 kg / cm ² G, residence time 30-120 minutes, and hydrocarbon partial pressure under reduced pressure, further pyrolyzed and subjected to steam distillation to separate light fraction and fuel residual oil. A method for pyrolyzing heavy oil, comprising a second pyrolysis step of separating and obtaining.