JPS63301295A - Method of thermal cracking of heavy oil - Google Patents

Abstract

PURPOSE:To attain thermal cracking of heavy oil in a reduced period of time using a reduced amt. of steam while limiting production of quinoline insolubles, by continuing reaction for a period of time which is in a predetermined proportion to feeding time after feeing of a product from a tube heating furnace into a reaction vessel. CONSTITUTION:A petroleum heavy oil as a stock oil is preheated to about 350 deg.C by a preheater furnace 2. The preheated heavy oil is mixed with a heavy end fraction of a thermal cracking product oil falling as a recycle oil in a distillation column 3. The mixture undergoes first thermal cracking at 490 deg.C or above at a cracking reaction rate of 30-45% in a tube heating furnace 4, thereby obtaining a product. Subsequently, the product is fed through a selector valve 5 into reaction vessels 6, 6' partially fed with the stock oil through a selector valve 7 from the distillation column 3. Selector valves 5, 7 are each actuated at predetermined time intervals so that the stock oil and the above-mentioned product are alternately fed into the two reaction vessels 6, 6'. A single feeding period is set at 50-100min, and 15-25pts. wt. steam, per 100pts.wt. stock oil comprising the use fed to the heating furnace 4 and the one fed to reaction vessels 6, 6' and heated to 500-700 deg.C using a steam superheater 8, is introduced into the reaction vessels 6, 6'. The contents of the reaction vessels 6, 6' are retained for 15-45% of the above-mentioned feeding period, thereby effecting second thermal cracking. The cracking product is quenched and extracted from the vessels.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for thermally decomposing heavy petroleum oil.

[Prior art]

For continuous pyrolysis treatment of petroleum-based heavy oil.

A first pyrolysis treatment step in which pyrolysis treatment is carried out in a tubular pyrolysis furnace, and a pyrolysis treatment product obtained in this first pyrolysis treatment step is alternately introduced into two reaction vessels to undergo a pyrolysis reaction. The method consists of a second pyrolysis treatment step, and before introducing the pyrolysis product obtained in the first pyrolysis treatment step into the reaction tank, petroleum-based heavy oil is partially filled in advance. Known (Special Publication No. 57-15795)
.

Such a thermal decomposition treatment method has already been carried out industrially, and its optimal operating conditions include, in the first thermal decomposition treatment step, temperature = 485-490°C, thermal decomposition reaction rate: 24-2
9% conditions were adopted, and in the second pyrolysis treatment step, high temperature steam with a temperature of 570 to 630°C was used, the time for charging the pyrolysis product to the reaction tank = 2 hours, and the reaction temperature: 400 to 630°C. Conditions of 430° C. and reaction time: 30 to 60 minutes are adopted. According to this method, 5 petroleum-based heavy oils are thermally cracked relatively efficiently, and the cracked oil containing aliphatic hydrocarbons as the main component and the atomic ratio of hydrogen and carbon (+ (/C)
An aromatic pitch of 1.0 or less can be obtained. However, in the case of this conventional method, the amount of steam used in the second pyrolysis treatment step is large, and it is still unsatisfactory from an economic point of view.In addition, in order to save the amount of steam used, the steam temperature is increased to 1000°C or higher. The disadvantage is that the heating method and tube material are significantly less economical than conventional methods, and furthermore, trying to reduce the amount of steam used increases the amount of quinoline dissolved in the pitch produced. Problems arise in that not only the quality of the pitch deteriorates, but also coking of the reaction tank becomes more likely to occur.

〔the purpose〕

The present invention seeks to solve the problems found in the prior art.

〔composition〕

According to the present invention, there is a first pyrolysis process in which petroleum-based heavy oil is pyrolyzed in a tubular heating furnace, and a pyrolysis product obtained in the pyrolysis process is alternately transferred to two reaction vessels. and a second pyrolysis treatment step in which the pyrolysis product obtained in the first pyrolysis treatment step is introduced into the reaction tank. In a method for pyrolysis treatment of petroleum-based heavy oil in which oil is partially charged, the first pyrolysis treatment step is performed at a temperature higher than 490° C. under conditions of a decomposition reaction rate of 30 to 45%, and the first pyrolysis step The pyrolysis product obtained in the treatment step is charged into the second pyrolysis step for a charging time of 50 to 100 minutes, and steam at 500 to 700°C is introduced into the reaction tank, and after the charging ,
After continuing to introduce the steam and holding the contents of the reaction tank for a period of time corresponding to 15% to 45% of the charging time, the contents of the reaction tank are rapidly cooled and then withdrawn from the reaction tank. , and the usage ratio of the steam is 100 in the total amount of heavy oil supplied to the tubular heating furnace of the first pyrolysis treatment step and heavy oil charged in advance to the reaction tank of the second pyrolysis treatment step. Provided is a method for thermally decomposing heavy petroleum oil, characterized in that the amount is 15 to 25 parts by weight.

In the present invention, in the pyrolysis treatment of petroleum-based heavy oil, in order to improve the process economy, the first pyrolysis treatment step is performed at a temperature higher than 4900C, preferably 495 to 500C using a tubular heating furnace. The reaction is carried out at a high reaction temperature of .degree. C., and the thermal decomposition reaction rate R is defined in a high range of 30 to 45%, preferably 35 to 45%.

According to the research conducted by the present inventors, as mentioned above, when the pyrolysis temperature in the tubular heating furnace is set higher than 490°C and the pyrolysis reaction rate is set at a high level of 30 to 4 parts, Since most of the heat of reaction in the subsequent reactor and the heat required for stripping of the cracked oil are supplied by the product from the tubular heating furnace, the amount of steam supplied as a heat source can be greatly saved. Since the temperature of the first reactor is maintained at a high level, the cracked oil is very easily steam-stripped, and as a result, the amount of steam can be significantly saved compared to the conventional method. was discovered. Furthermore, the thermal decomposition reaction temperature of heavy oil, including the reaction temperature in the reaction tank, can be maintained at a higher overall temperature level in the case of the present invention adopting the above configuration compared to conventional methods. As a result, the by-product of quinoline dissolved matter is suppressed.

There is also the advantage that the thermal decomposition reaction time is shortened and pitch with reduced quinolinated content can be produced with good productivity. When the thermal decomposition reaction temperature of heavy oil increases, both the polycondensation reaction rate K (polymerization), which causes the formation of quinolinated components, and the decomposition reaction rate K (decomposition), which generates cracked gas and cracked oil, increase. The rate of increase in the reaction rate is greater for K (decomposition),
In the end, the ratio of the two: K (decomposition)/K (polymerization) becomes large,
The production rate of quinoline dissolved components in the pitch will be suppressed. Furthermore, in the present invention, in order to suppress the production rate of quinoline dissolved components and obtain pitch with uniform properties, after the product from the tubular heating furnace is charged into the reaction tank, heavy oil remains in the reaction tank. A fixed percentage of the tensioning time to equalize the time, usually 15% to 45%.

Preferably, a configuration is adopted in which the reaction is continued for a period of time of 25 to 45%.

Since the pitch thus obtained is homogeneous with relatively little quinolinous content, it not only suppresses coking in the reaction tank.

It has a high viscosity content and is suitable as a binder for producing coke for steelmaking, and also has excellent burnout properties and high product value when used as a fuel.

The petroleum heavy oil used as a raw material in the present invention is:
These include atmospheric residual oil, vacuum residual oil, thermal decomposition residual oil, and various oil refinery residual oils, such as Duoturu extracted oil, furfural extracted oil, and extracted residual oil with paraffinic solvents such as propane, butane, and pentane.

Next, one embodiment of the present invention will be explained with reference to the drawings.

The drawing shows a flow sheet for carrying out the invention.

Raw material oil is sent from the raw material tank and sent to the raw material preheating furnace 2 at 35
It is preheated to about 0°C and enters the distillation column 3. Here, it is mixed as recycled oil with the heavy end fraction of cracked oil that falls to the bottom of the tower. The ratio of this recycled oil to the raw material is 0
．． 1.0-0.25, preferably 0.15-0.20. The raw oil mixed with the recycled oil is sent to the tubular heating furnace 4.
sent to. In the tubular heating furnace, the raw material oil is heated to 490 to 500
Decomposition by heating to a temperature of 495-500'C, preferably 495-500'C.

In the present invention, the reaction temperature in this tubular heating furnace is set at 490 to 500°C, and the thermal decomposition reaction rate R is set at 30°C.
-45%, preferably in a high range of 35 to 4 brocades. Note that the thermal decomposition reaction rate R (%) in this case is determined by the following formula.

-B R=-X100 (%) A: Proportion of components with a boiling point of 538°C or higher in the tubular heating furnace feedstock B: Proportion of components with a boiling point of 538°C or higher in the thermal decomposition product obtained from the tubular heating furnace In the present invention, by operating the tubular heating furnace 4 under the conditions as described above, various advantages as described in detail later can be obtained.

The outlet pressure in the heating furnace 4 is normal pressure to 4 kg/a#, and the reaction time is usually about 0.5 to 10 minutes, preferably about 2 to 5 minutes. The high-temperature thermal decomposition product obtained in the heating furnace 4 is flashed and introduced into a predetermined reaction tank 6 via a switching valve 5. Partially fill the raw material oil through.

The charging amount is 5 to 18%, preferably 10 to 15% of the total charging amount of the reaction tank. Further, the temperature of the pre-charged raw material oil is about 340°C. The switching valves 5 and 7 are operated at regular intervals, and feed oil and the thermally decomposed product from the heating furnace 4 are periodically and alternately charged into the two reaction vessels 6 and 6'. Through such periodic operations, the thermal decomposition treatment of the thermal decomposition product continuously supplied from the heating furnace 4 is continuously carried out in the reaction tank.

The reaction vessels 6, 6' are usually cylindrical containers, and are provided with a raw material inlet, a heating medium gas inlet, an outlet for cracked gas, cracked oil, and a heating medium gas, and a residue outlet. Additionally, a stirrer can be installed if necessary.

Steam as a heating medium gas is heated to a temperature of 500 to 700°C, preferably 5°C by a steam superheater 8.
After heating to 50-650°C, it is blown into reaction Mj 6.6' via 9,9'. When charging the thermal decomposition product from the heating furnace 4 into the reaction N96, 6', the temperature of the preliminary charging in the reaction tank immediately before charging is about 340°C.

At the start of this charging, the temperature inside the reaction tank was 430 to 44℃.
The temperature rises to 0° C., and the decomposition reaction and polycondensation reaction of the thermally decomposed product introduced into the tank further proceed. In the present invention, the duration of this one time is set to about 50 to 100 minutes, preferably about 60 to 90 minutes.

At the end of this filling, the softening point of the residue in the tank (hereinafter simply referred to as pitch) increases. Even after this filling is completed, high temperature steam is continued to be blown in to further advance the reaction. In the present invention, the reaction time after tensioning is 15%-45% of the tensioning time.
%, preferably 25 to 4 hours. As mentioned above, in the case of the present invention, the pyrolyzed product from the tubular heating furnace undergoes a considerable pyrolysis reaction and the temperature is high. Although it is not necessary to use much reaction time (holding time), the pitch obtained in this way has poor homogeneity. Therefore, in the present invention, in order to obtain a homogeneous pitch, the setting time is limited to 50 to 100 minutes.

After the filling is completed, high-temperature steam is continued to be blown for about 15 to 45% of the filling time to continue the thermal decomposition treatment.

In the present invention, the temperature of the steam supplied to the reaction tank is 5
It is sufficient to use steam at a relatively low temperature of 00 to 700°C, and the supply amount is also small, and the total amount of raw oil supplied to the tubular heating furnace 4 and the reaction vessels 6 and 6' is 1 kg.
A ratio of 0.15 to 0.25 kg is sufficient. This is a major advantage of the present invention. In the case of the present invention, the pyrolysis product from the tubular heating furnace has already undergone a considerable pyrolysis reaction and is at a high temperature of 490 to 500°C, so the pyrolysis product is poured into the reaction tank. In some cases, the retained heat supplies a considerable amount of the hot air required for the pyrolysis reactions in the reactor and for stripping the cracked oil from the reaction products, thus significantly reducing the amount of steam supplied as a heat source. can do.

In addition, since the temperature of the reaction tank is maintained at a higher level than in the conventional case, the cracked oil is much easier to strip, and the partial pressure of the cracked oil in the reaction tank is lowered to make stripping easier. The role of steam supply can also be reduced.

Furthermore, in the case of the present invention, the thermal decomposition reaction rate in the heating furnace is high, and a considerable amount of cracked oil produced in the heating furnace is supplied to the reaction tank as paper, so compared to the conventional case, one reaction tank is used. Since the amount of heat required for the thermal decomposition reaction and stripping of cracked oil is small, the amount of steam used can be significantly reduced as a result.

During charging of the thermal decomposition products from the heating furnace 4 and during the subsequent reaction treatment, gaseous substances and steam of the thermal decomposition products are distilled out from the upper discharge port of the reaction tank and sent to the distillation column 3. send.

After the reaction in the reaction tank 6 is completed, cooling (quenching) of the reaction tank 6 is started, and the reaction tank temperature is lowered to 320 to 380°C to substantially stop the reaction, and then the pitch in the reaction tank 6 is Immediately transfer to liquid pitch storage tank 10.

This pitch storage tank 10 has a stirrer, and the reaction tanks 6, 6'
It also has the function of alternately receiving pitches from other sources and mixing them uniformly. In addition, superheated steam is blown into the bottom of the tank to maintain the pitch temperature in the tank at 300 to 370°C to keep it in a liquid state, and light fractions are stripped from the pitch, which is distilled via line 11. Send it to Tower 3. The pitch in the liquid pitch storage tank 10 is as follows.

After being cooled and solidified in the pitch assimilation facility 12, it is sent to the pitch storage facility 3.

According to the present invention, as described above, the operating conditions of the tubular heating furnace and the related operating conditions of the reaction tank are defined within a specific range, thereby improving the conventional industrially practiced method. In comparison, the amount of steam supplied to the reaction tank can be significantly reduced, which can significantly improve process economics and improve product production efficiency.

〔Example〕

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

Example 1 Vacuum residue oil of a mixed crude oil of Middle Eastern and Mexican origin having the following properties was used as a raw material oil.

Table 1 This raw material oil was thermally decomposed according to Flow Sheet 1 shown in the drawing.

That is, raw material oil is continuously passed through a preheating furnace 2 at a flow rate of 50 t/hr, preheated to 350° C., and then supplied to a distillation column 3. Here, it is mixed with the heavy end fraction of the cracked oil and supplied to the tubular heating furnace 4 at a flow rate of 151.5 t/hr, that is, the amount of recycled heavy end fraction is 15 times the amount of raw material supplied to the preheating furnace. Then, heat treatment was performed under the conditions shown in Table 2, and the resulting thermal decomposition product was first poured into the reaction tank 6 through the switching valve 5 while being flushed.

Prior to charging, raw oil was charged into the reaction tank 6 in advance from the distillation column 3 via the switching valve 7 at a rate of 12% of the total amount of raw oil charged into the reaction tank. After charging the reaction product from this heating furnace, the switching valve is operated to transfer the product to the other reaction tank 6', which has also been preliminarily charged with raw material oil.
It was introduced in The preliminary charging of raw material oil and the charging of the thermal decomposition product from the tubular heating furnace into the reaction tank 6°6' were carried out alternately at regular intervals as described above. Further, each reaction tank 6, 6' had a height of 14 m, an inner diameter of 5.5 m, and had a stirrer inside. reaction tank 6,
Superheated steam was introduced into 6' from its bottom.

The thermal decomposition products from the tubular heating furnace are charged into the reaction vessels 6 and 6' as described above, held at the reaction temperature for a certain period of time, and further thermal decomposition treatment is continued.
°C) and transferred to a liquid pitch storage tank 9 (temperature: 340 °C) into which superheated steam was blown.

On the other hand, cracked gas and cracked oil were distilled out along with steam from the upper part of the reaction tanks 6 and 6' and sent to the distillation column 3, where the cracked gas and cracked oil were separated.

Table 2 shows the above heat treatment results in relation to various operating conditions.
Shown below.

Table 2 Example 2 The flow was basically the same as that of the equipment used in Example 1, but the raw material throughput was 300 kg/hr and on a smaller scale.

Thermal decomposition treatment was carried out using equipment that performs preheating and decomposition simultaneously in a tubular heating furnace without having a preheating furnace.

That is, 45 kg/hr of the heavy end fraction of cracked oil from the bottom of the distillation column was mixed with 264 kg/hr of raw oil.

It was supplied to a tubular heating furnace at a flow rate of 309 kg/hr and heat-treated under the conditions shown in Table 3, and the resulting thermal decomposition product was poured into the reaction tank while being flashed. Prior to charging, 36 kg of raw material oil was charged into the reaction tank from the raw material tank. After charging the reaction product, the switching valve was operated to introduce the product into the other reaction tank, which was also preliminarily charged.

Superheated steam from a steam superheater was introduced into the reactor from the bottom. After filling the reaction tank with the product from the heating furnace, the introduction of superheated steam is continued, and the reaction temperature is maintained for a certain period of time to continue the thermal decomposition treatment.
Quenched and transferred to liquid pitch storage tank. Meanwhile, cracked gas and cracked oil are distilled out along with steam from the upper part of the reaction tank.
It was sent to a distillation column, and the cracked gas and cracked oil were separated by distillation, and the heavy end fraction of the cracked oil was fed to a tubular heating furnace together with the raw oil.

Preliminary charging of raw material oil into the reaction tank was 12% of the total charging amount, and the recycling amount of the heavy end fraction of cracked oil was 15% of the amount of raw material oil processed, which was carried out under the same conditions as in Example 1. . Moreover, the same vacuum residual oil as in Example 1 was used as the raw material oil. The heat treatment results are shown in Table 3 in relation to various operating conditions.

Table-3

[Brief explanation of drawings]

The drawing shows a flow sheet of the method of the invention. 2... Preheating furnace 3... Distillation column 4...Tubular heating furnace 6.6'・・・Reaction tank 13...Pitch storage tank

Claims (1)

[Claims] (1) A first pyrolysis treatment step in which petroleum-based heavy oil is pyrolyzed in a tubular heating furnace, and a pyrolysis product obtained in the pyrolysis treatment step is alternately introduced into two reaction vessels. a second pyrolysis treatment step in which a pyrolysis treatment is carried out, and before the pyrolysis product obtained in the first pyrolysis treatment step is introduced into the reaction tank, petroleum-based heavy oil is partially dissolved in advance. In the pyrolysis treatment method for petroleum-based heavy oil that is poured into a tank, the first pyrolysis treatment step is performed at a temperature higher than 490° C. under conditions of a decomposition reaction rate of 30 to 45%, and in the first pyrolysis treatment step, The obtained pyrolysis treatment product is charged into the second pyrolysis treatment step for a charging time of 50 to 100 minutes, and at the same time, 500
~700°C steam is introduced, and after the charging, the steam is continued to be introduced and the contents of the reaction vessel are heated for 15 minutes during the charging time.
% to 45% of the time, the contents of the reaction vessel are rapidly cooled and discharged from the reaction vessel, and the proportion of the steam used is the same as that of the tubular heating of the first pyrolysis treatment step. Petroleum in an amount of 15 to 25 parts by weight based on 100 parts by weight of the heavy oil supplied to the furnace and the heavy oil charged in advance into the reaction tank of the second pyrolysis treatment step. A method for thermal decomposition of heavy oil.