JPS6158513B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for lightening heavy hydrocarbons by subjecting them to a thermal decomposition reaction in the presence of a hydrogen-donating solvent.

Conventionally, in order to lighten heavy hydrocarbons, various methods have been known in which heavy hydrocarbons are catalytically hydrocracked under hydrogen pressure. However, all of these catalytic cracking methods involve problems such as catalyst deterioration, equipment clogging due to coking and pitting, and hydrogen consumption efficiency, and it is unclear how to solve these problems. This has become an important technical issue in this type of technology field. In fact, much research has been devoted to solving these problems, and many patents have been proposed for the results, but nothing definitive has yet been proposed.

In such hydrocracking reactions of heavy hydrocarbons, a method is known in which a solvent that liberates hydrogen under the reaction conditions, that is, a hydrogen-donating solvent, is used as a direct hydrogen source for the reaction system, without using hydrogen gas. (Special Publication No. 32-9083). This method has high hydrogen consumption efficiency because it performs the hydrothermal cracking reaction with a minimum amount of hydrogen.
Although it is a small amount, coke and pitch are produced, clogging the reactor and hindering continuous operation.

The present invention solves the problems of the conventional methods described above, especially the problems of clogging of the reactor due to by-product pitch and coke that occur when heavy oil becomes soft, and enables stable operation over a long period of time. This method was developed to develop a hydrogen-donating solvent in which a hydrogen-donating solvent is present in the reaction system, and the reaction is carried out in two stages. The reaction is carried out for a long time in the state of extrusion flow, and the softening of heavy oil is achieved while substantially avoiding the by-product of pitch. It is characterized by the ability to convert substances that tend to form into a pitch into a pitch by performing a short-time reaction.

That is, according to the present invention, in the presence of a hydrogen-donating solvent, heavy hydrocarbons are reacted using a tower reactor at a reaction temperature of 380 to 420°C and a reaction pressure of 20 to 150°C.
By carrying out thermal decomposition under the conditions of Kg/cm ² G and reaction time of 30 minutes to 5 hours, in an extrusion flow state, by adjusting the reaction temperature, pressure and time, the pitch-like substance is reduced to 1% by weight or less. After obtaining decomposition product oil, this decomposition product oil is heated to a reaction temperature of 450 to 450°C using a tubular reactor.
550℃, reaction pressure 20-150Kg/cm ² G and reaction time 5
By controlling the reaction temperature, time and pressure under conditions of seconds to 5 minutes, and performing thermal decomposition by flowing through the tubular reactor, a decomposition product containing a pitch-like substance with good separability is obtained. A method for softening heavy hydrocarbons is provided.

In the present invention, heavy hydrocarbons include sulfur compounds and nitrogen compounds, as well as metals such as vanadium, nickel, and iron, of which at least 10% by volume is heated to 550°C or higher. It has a boiling point, and its specific gravity at 20℃ is 0.93.
These hydrocarbons include petroleum crude oil, heavy oil extracted from tar sands, atmospheric distillation residue oil, vacuum distillation residue oil,
Includes crude oil and various other heavy oils commonly referred to as "black oil." Such heavy oil usually has a content of 100 ppm or more, and in many cases,
Contains over 150ppm of metals.

In addition, the term "pitch-like substance" or "pitch" as used herein refers to benzene-insoluble matter contained in decomposed oil, and this includes coke as well.

In addition, the hydrogen-donating solvent in the present invention can be used under the reaction conditions used in the present invention, that is, at 380 to 550°C.
Any material can be used as long as it liberates hydrogen at a temperature of These substances can be broadly classified into alcohol-based, hydrocarbon-based, and other types.

Examples of alcohols include methanol, ethanol, propanol, benzyl alcohol,
- Primary alcohols, secondary alcohols, tertiary alcohols such as phenylethanol, 3-fluorobenzyl alcohol, cyclohexanol, 2,3-butanediol, 2-propanol, 2-butanol, etc.
alcohols, allyl-type unsaturated alcohols, etc. Alcohols with less steric hindrance donate hydrogen more easily.

Tetralin is the most common example of hydrocarbons, but other examples include cyclohexane, 1.6
-dimethyltetralin, cyclohexene, 1.3
- or 1,4-cyclohexadiene, octarine, 6-methyltetraline, anthracene oil, creosote oil, and the like.

Examples other than the alcohols and hydrocarbons mentioned above include indoline, pyrrolidine, tetrahydroquinoline, piperidine, dioxane, tetrahydrofuran, isopropylamine, N-methylpyrrolidone, formic acid, aromatic aldehydes, aliphatic saturated carbonyl compounds, and amines. , ether, etc.

In the reaction system of the present invention, the hydrogen-donating solvent mainly donates hydrogen to the fragments generated by thermal decomposition of heavy oil to prevent their recombination and stabilize them, and also dissolves the products. It plays the role of preventing heavy oil from turning into pitch and coke, and also promoting the thermal decomposition of heavy oil.

One of the advantages of pyrolysis of heavy oil in the presence of a hydrogen-donating solvent is that the precipitation of coke and pitch can be greatly reduced; however, even in this case, the by-product coke is Although it is relatively small, it accumulates in the reactor and causes equipment clogging, making long-term continuous operation difficult. Therefore, using only this hydrogen-donating solvent is not enough to solve the equipment clogging problem. It is not possible.
The present invention attempts to solve the problem of device clogging by making use of the above-mentioned advantages found in the use of hydrogen-donating solvents and by adding certain measures to this, but based on research conducted by the present inventors, For example, in the thermal decomposition reaction of heavy oil, lightening and pitching can be carried out separately by selecting reaction conditions, and when lightening and pitching are carried out separately, the pitching can be carried out separately. The knowledge that it is possible to adopt conditions that do not cause device clogging in the process was obtained, and the two-stage decomposition method of the present invention was developed based on this knowledge.

Both the first step and the second step of the present invention are carried out in the presence of a hydrogen-donating solvent; in this case,
The amount of hydrogen-donating solvent used is mainly determined by its hydrogen-donating ability and solubility, and is not unambiguously determined, but generally it is 10 to 1000 parts by weight per 100 parts by weight of heavy oil. parts, preferably in the range from 50 to 500 parts by weight. In addition, it is desirable to regenerate and recycle the hydrogen-donating solvent after the reaction, so the basic skeleton remains in the reaction system without being decomposed and supplies only hydrogen, such as tetralin or cyclohexane. It is advantageous to use those having a cyclic skeleton which are susceptible to dehydrogenation and hydrogenation reactions. Such substances are dehydrogenated and converted into unsaturated compounds in the reaction system, but after the reaction,
By hydrogenation, it can be easily regenerated into the original hydrogen-donating solvent, and can be recycled to the reaction system for use again.

The first step in the present invention involves a reaction temperature of 380 to 420
℃, preferably 400-430℃, reaction pressure 20-150Kg/
cm ² G, preferably 30 to 100 Kg/cm ² G. Under such conditions, heavy oil is less likely to be turned into pitch, and it is possible to reduce the weight of heavy oil while substantially suppressing the by-product of pitch. The reaction time is determined depending on the desired degree of thermal decomposition, but since the reaction temperature is low, a long time is required, and is generally in the range of 30 minutes to 5 hours.

A column type reactor is used as the type of reactor in the first step, and it is particularly suitable to use a packed column type reactor or a bubble column type reactor in which the fluidization state is controlled with an inert substance. It is important to make the flow state of the reactants in the reactor as homogeneous as possible. If the flow state of the reactants becomes as homogeneous as possible, in other words, if the residence time distribution becomes inhomogeneous, pitches will tend to precipitate when the raw materials flow upward, and When flowing into the water, the decomposition of heavy components tends to be insufficient. Therefore, in the present invention, extrusion flow (piston flow) is employed in order to homogenize the inside of the reactor. In the case of a completely mixed flow, a residence time distribution occurs and pitches are likely to be generated, which is not preferable.

When carrying out the first step, it is important to maintain most of the hydrogen-donating solvent in the liquid phase in order to carry out efficient reaction operations, so that the polycondensation product remains soluble in the solvent. Since the reactor is discharged at a temperature of 100 mL, sufficient thermal decomposition can be carried out without clogging the reactor.

The second step in the present invention involves a reaction temperature of 450 to 550
It is carried out under the conditions of ℃ and reaction pressure of 20 to 150 Kg/cm ² G. Although the decomposition product oil from the first step has been decomposed and lightened, the polycondensation products float in the product oil and are difficult to separate from the product oil. Such polycondensation products are converted into pitch or coke-like materials by reacting for a short time, usually from 5 seconds to 5 minutes, under the reaction conditions described above. In this case, the metal content contained in the heavy oil is concentrated in the pit-like substance, and the effect of metal removal is also achieved.
After the reaction, these pitch and coke-like substances are separated and removed by centrifugation, solid-liquid separation means such as a hydrocyclone, or solvent extraction to obtain a lightened oil with low metal content and asphaltene content.

The reaction in the second step is mainly aimed at forming a pitch, but in the present invention, the polycondensation product produced in the first step, which is easily formed into a pitch, is converted into a pitch, so it can be carried out in an extremely short time. The problem of reactor blockage due to production pitch is eliminated. That is, in this second step, a tubular reactor is used as the reactor. In this tubular reactor, the reaction can be completed in a short time, so the linear velocity of the reactants can be increased, and the generated pitch and coke-like substances adhere to and accumulate on the vessel walls. It is discharged outside the reactor without any waste.

When carrying out the method of the present invention, the first and second steps are operated at different temperatures, as described above, and in this case, the temperature in the first step is
It is important to make the temperature lower than that in the second step. Hydrogen-donating solvents give hydrogen to radicals generated by thermal decomposition of heavy oil during the reaction, but when the temperature rises beyond a certain range, the concentration of radicals becomes too high and the polycondensation of radicals with each other becomes unstable. As the amount increases, pitch and coke are more likely to be produced, and the hydrogen-donating solvent itself decomposes more often. Furthermore, if the temperature is too low, thermal decomposition of heavy oil will not occur. Considering these things, the first
As mentioned above, the temperature of the step is preferably 380 to 450°C, preferably 400 to 430°C. The temperature in the second step is such that the polycondensation product produced in the first step, which is easy to make into a pitch but is difficult to separate, is made into a pitch or coke shape that is easy to separate. Optional, but typically 450
-550°C, preferably 460-500°C.

In the present invention, since a hydrogen-donating solvent is used, the gas necessary to maintain the pressure inside the reactor is not necessarily hydrogen gas, but nitrogen,
Steam, paraffinic light hydrocarbons and other hydrocarbon cracking gases are optionally used.

Next, preferred embodiments of the method of the present invention will be described with reference to the drawings.

In the drawings, 3 represents a mixer, 5 represents a heating furnace, 7 represents a first reactor, and 10 represents a second reactor. Heavy hydrocarbons, which are raw materials, are sent to a mixer 3 via a pipe 1. Further, a hydrogen-donating solvent is sent to the mixer 3 via a pipe 2, where the heavy hydrocarbons and the hydrogen-donating solvent are uniformly mixed. The mixed liquid obtained in the mixer 3 is sent to a heating furnace 5 together with circulating hydrogen through a pipe 4 for preventing coking, and is heated up. The raw material mixture heated to a predetermined reaction temperature is introduced into the first reactor 7 together with the circulating hydrogen gas from the pipe 6, where it is hydrothermally decomposed. In this case, the decomposition rate is about 50 to 90% by weight based on the components at 550°C or higher.

According to the present invention, in the reaction mixture lightened in the reactor 7, pitch-like substances that may cause clogging of the reactor are substantially ignored, and the amount thereof is at most 1 weight. % or less. This polycondensation product exists in a suspended state in the reaction mixture and does not particularly block the reactor.

The reaction mixture from the reactor 7 is introduced into the second reactor 10 with its linear velocity accelerated by the circulating hydrogen gas from the pipe 8. Further, according to this embodiment, a portion of the pitch separated by the pitch separator 19 in the latter stage is circulated to the reactor 10. Circulation of this pitch portion provides extremely large advantages in terms of promoting the decomposition reaction and demetallizing heavy hydrocarbons. That is, according to the research of the present inventors, metals such as vanadium and nickel contained in heavy oil are deposited and concentrated in the pitch thus formed in the second reactor 10,
Furthermore, it has been found that this material exhibits a catalytic effect on thermal decomposition reactions. In the present invention, the preferred pitch to be recycled is a benzene-insoluble pitch containing 0.1 to 40% by weight, preferably 0.5 to 20% by weight of a catalytically active metal such as vanadium or nickel, and the amount of the circulating amount is such that the pitch is present in the reaction mixture in an amount of 1 to 50% by weight, preferably 5 to 30% by weight. Furthermore, this pitch circulation has the effect of forming pitches with good separability in the reactor 10 and facilitating separation of the pitches in the separator 19. In this reactor 10, pitch is produced in a ratio of 0.1 to 10% by weight in the raw mixed oil, and at the same time some lightening of the heavy oil is also achieved.

The product from the second reactor 10 is led to the gas separator 12 through a pipe 11, where the gas contained in the product is separated, and the separated gas is sent from the pipe 14 to the gas purification system. introduced in 15, while
The remaining produced oil passes through the pipe 13 to the pitch separator 1.
Sent to 9th. Hydrogen is separated from other gases in the reaction product gas sent to the gas purification system 15, and the hydrogen is circulated through the pipe 17 and the make-up hydrogen from the pipe 18 to the reaction system through the pipes 4, 6, and 8. . The amount of hydrogen gas to be circulated is about 0 to 50 per 1 of raw material mixed oil under standard conditions. In the present invention, a hydrogen-donating solvent is used,
Since the hydrogen required for the decomposition reaction is substantially supplied by the hydrogen liberated from this solvent, the consumption of circulating hydrogen gas is small, and the consumption is usually 20Nm ³ per 1Kl of raw mixed oil. That's about it.

After the produced oil is separated into its pitch portion in the separator 19, it passes through the pipe 21 and is introduced into the solvent purification system 22, where it is separated into the solvent and the produced oil, and the produced oil is taken out from the pipe 23. . On the other hand,
The solvent enters a hydrogenation step 25 via a pipe 24, where it is contacted with hydrogen gas from a pipe 26 to be hydrogenated, and is recycled from the pipe 2 to the mixer 3 again as a hydrogen-donating solvent.

As described above, the method of the present invention divides the thermal decomposition reaction of heavy hydrocarbons into two stages, and performs the thermal lightening reaction and the pitching reaction separately under specific conditions. It overcomes the problem of equipment blockage due to by-product pitch and coke, and obtains high-quality lightened oil with a reduced hydrogen consumption rate, and is of great industrial significance.

Next, the present invention will be explained in more detail with reference to Examples.

Example Filled with α-alumina beads with a diameter of 2 mm
The thermal decomposition reaction related to the first step was carried out using a reactor made of SUS316 with a diameter of 1 inch and a length of 3 m.
In this case, commercially available tetralin was used as the hydrogen-donating solvent, and Boscan crude oil shown in Table 1 was used as the heavy hydrocarbon.

Table 1 (Properties of Boscan crude oil) Specific gravity: 0.9974 Sulfur content: 5.19% by weight Vanadium content: 1200ppm Nickel content: 108ppm N-pentane insoluble content: 11.9% by weight ASTM distillation properties: Below 175°C 0.5% by volume 175-260°C 3.0% by volume 260-350°C 8.5% by volume 350-500°C 15.0% by volume Above 500°C 73.0% by volume On the other hand, under the conditions of a reaction temperature of 415° C., a pressure of 30 Kg/cm ² G, and a superficial velocity of 2 hr ⁻¹ , the mixed solution was flowed upward from the bottom at a rate of 240 ml/hr. Also, for this reactor,
Hydrogen gas was flowed in parallel with the raw material mixed oil at a rate of 10/hr. In this case, the ratio G/L of hydrogen gas and raw material mixed oil was 40.

As a result of carrying out the reaction in this manner, a produced oil (including the solvent) having the properties shown in Table 2 was obtained. In addition, the gas generation amount is 2.4% by weight based on the raw material mixed oil.
It was hot.

The decomposition rate in this case was 58% by weight (based on components at 550°C or higher).

Table 2 (Properties of produced oil) Specific gravity: 0.972 Sulfur content: 2.19% by weight Vanadium content: 577ppm Nickel content: 99ppm N-heptane insoluble content: 4.67% by weight Benzene insoluble content: 0.1% by weight ASTM distillation properties: 175°C or less 1.0% by volume 175-260°C 3.9% by volume 260-350°C 15.5% by volume 350-500°C 25.8% by volume 500°C or higher 53.8% by volume Using the produced oil obtained in the first step as a raw material, the reaction related to the second step is carried out. I did it. In this case, the reactor used was a 50 m reaction tube made of SUS316 with an inner diameter of 2 mm and an outer diameter of 3 mm, wound into a spiral shape with a diameter of 100 mm.

The reaction was carried out under the conditions of a reaction temperature of 450° C. and a reaction pressure of 30 Kg/cm ² G, with the produced oil being supplied at a rate of 300 c.c./hr.
Flow upward from the bottom, and at the same time hydrogen gas
It was flowed cocurrently at a rate of ml/hr.

The reaction product obtained in this way was
The resulting oil was filtered through filter paper to separate pitch-like substances from the resulting oil. The pitch-like material was produced at a ratio of 3.5% by weight based on the raw material oil. Further, the amount of gaseous substances was 1.7% by weight based on the raw material oil. Next, Table 3 shows the properties of the thus obtained product oil (including the solvent).
The vanadium content in the separated pitch-like substance was 1.02% by weight and the nickel content was 490 ppm, confirming that the metal content in the raw oil was concentrated in this pitch-like substance.

In addition, in this case, the decomposition rate (based on components at 550°C or higher) for the feedstock oil based on the product oil obtained in this second step is 93% by weight, and in this second step, the thermal decomposition rate is 35% by weight. was achieved.

Table 3 (Properties of produced oil) Specific gravity: 0.9471 Sulfur content: 1.51% by weight Vanadium content: 27ppm Nickel content: 2ppm or less N-heptane insoluble content: 0.4% by weight Benzene insoluble content: 1.5% by weight ASTM distillation properties: 175℃ Below 15.0% by volume 175-260°C 13.0% by volume 260-350°C 29.0% by volume 350-500°C 35.0% by volume Above 500°C 8% by volume Other than pressurizing using nitrogen gas instead of hydrogen in the first step The reaction was carried out in the same manner as in the first step. Table 4 shows the properties of the resulting oil (including the solvent).

Table 4 (Properties of produced oil) Specific gravity: 0.976 Sulfur content: 1.96% by weight Vanadium content: 508ppm Nickel content: 90ppm N-heptane insoluble content: 4.10% by weight Benzene insoluble content: 0.5% by weight ASTM distillation properties: 175°C or less 1.0% by volume 175-260°C 3.2% by volume 260-350°C 14.3% by volume 350-500°C 25.0% by volume Above 500°C 56.5% by volume Comparative example Weight of feedstock oil and hydrogen-donating solvent (tetralin) shown in Table 1 A 1:1 ratio mixture was pyrolyzed in one step for comparison. In this case, the same reactor as in the first step was used.

The reaction was carried out under conditions of a reaction temperature of 450℃ and a reaction pressure of 50Kg/cm ² G. The raw mixed oil was flowed upward from the bottom of the reactor at a rate of 240ml/hr, and at the same time hydrogen gas was injected at 10N.
/hr in parallel flow.

The reaction product obtained in this way was transferred to the pore 1
The resulting oil was filtered through μ paper to separate the pitch-like substance from the resulting oil. Pitch-like material is 2.3% by weight based on raw oil
generated at a rate of In addition, gaseous substances were produced at a ratio of 4.8% by weight based on the raw material oil.

Table 5 shows the properties of the product oil thus obtained.

Table 5 (Properties of produced oil) Specific gravity: 0.968 Sulfur content: 1.96% by weight Vanadium content: 340ppm Nickel content: 52ppm N-heptane insoluble content: 2.37% by weight Benzene insoluble content: 2.3% by weight ASTM distillation properties: 175°C or less 8% by volume 175-260°C 17.0% by volume 260-350°C 16.5% by volume 350-500°C 19.0% by volume Above 500°C 39.5% by volume In this case, if the reaction is continuously operated for 20 hours, there will be a difference in the reactor. Pressure was generated and oil flow became impossible. In addition, a considerable amount of coke-like material was observed on the reactor wall.

[Brief explanation of the drawing]

The drawing shows an equipment system diagram for an embodiment of the invention. In the figure, numeral 3 is a mixer, 5 is a heating furnace, and 7 is a first
a reactor, 10 a second reactor, 12 a gas separator,
19 indicates pitch separators.

Claims (1)

[Claims] 1. In the presence of a hydrogen-donating solvent, heavy hydrocarbons are reacted at a reaction temperature of 380 to 420 using a tower reactor.
℃, reaction pressure 20-150Kg/cm ² G and reaction time 30 minutes ~
By carrying out thermal decomposition under extrusion flow conditions for 5 hours by adjusting the reaction temperature, pressure and time, a cracked oil with a pitch-like substance of 1% by weight or less was obtained. Oil, using a tubular reactor, reaction temperature 450-550℃, reaction pressure 20-150Kg/cm ²
By controlling the reaction temperature, time and pressure under the conditions of G and reaction time of 5 seconds to 5 minutes to conduct thermal decomposition by flowing through the tubular reactor, a pitch-like material with good separability is contained. A method for lightening heavy hydrocarbons, characterized by obtaining cracked oil. 2. The method according to claim 1, wherein the reaction pressure is adjusted using at least one selected from hydrogen, nitrogen, steam, paraffinic soft hydrocarbons, and decomposed gas of hydrocarbons. 3. At least one selected from cyclohexane, cyclohexene, tetralin, decalin, anthracene, and derivatives thereof, or 20% by weight of at least one of these as a hydrogen-donating solvent.
The method according to claim 1 or 2, which uses a mixture containing the above. 4. The method according to any one of claims 1 to 3, in which the hydrogen-donating solvent is used in an amount of 0.5 to 5 times the weight of the raw material heavy hydrocarbons. 5. A method according to any one of claims 1 to 4, in which the pitch-like substance is separated from the oil produced in the second cracking step and then recycled to the second separation step.