JPS6338076B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a processing method for producing cracked oil and aromatic pitch by thermally decomposing heavy petroleum oil. Recently, with the rise in crude oil prices, it has become increasingly important to crack down heavy oil to make it softer and increase the yield of oil from crude oil. The present applicant previously published Japanese Patent Publication No. 54-15444 as a thermal decomposition treatment method for petroleum-based heavy oil.
Special Publication No. 15795 was submitted. In other words, the special public service in 1977
-No. 15444 is equipped with multiple reactors, and petroleum-based heavy oil is introduced into the first reactor, and after filling is completed, the second reactor is
proposed a method of continuously heat-treating petroleum-based heavy oil by sequentially switching the charging of petroleum-based heavy oil into a reactor. We proposed a method in which a portion of low-temperature petroleum-based heavy oil is injected into the reactor in advance to alleviate material fatigue in the reactor caused by heat shock.
Using technology based on these patents, the applicant has been operating thermal decomposition treatment of asphalt, which is a heavy petroleum oil, for many years and has achieved industrial results. However, in some cases, the properties of the pitch, which is a thermal decomposition product, became quite non-uniform, and as a result, a large amount of coke was deposited in the reactor, which hindered long-term stable operation. Furthermore, in some cases, the yield of cracked oil may be low, impairing economic efficiency. Therefore, there has been a strong demand for a technology for a thermal decomposition treatment method that can stably produce high-quality pitch while maintaining the yield of cracked oil. As a result of many years of research on thermal decomposition treatment methods for petroleum-based heavy oil, the present inventors discovered that the temperature rise curve during the feeding period of feedstock oil has a great significance.Herein, the present invention solves the above-mentioned problems. completed. That is, the present invention uses a series consisting of one heating furnace and a plurality of reaction cans, pouring petroleum-based heavy oil from the heating furnace into the first reaction can, and after completion, pouring it into the second reaction can, At the same time, a non-reactive heating medium gas is blown into each reaction vessel from the bottom of the reaction vessel, and the non-reactive heating medium gas is brought into direct contact with petroleum-based heavy oil to cause a thermal decomposition reaction. Thermal decomposition treatment of petroleum-based heavy oil to produce cracked oil and aromatic pitch, characterized by increasing the liquid phase temperature of the reactor during a period of time to a range between the following formulas and formulas. Method T _L = 440-90exp (-0.085θ) () T _L = 400-100exp (-0.085θ) () However, T _L liquidus temperature (℃), θ; elapsed time after filling heavy oil ( minute). The present invention will be explained in detail below. The petroleum heavy oil used as the raw material oil in the present invention is
Any oil included in petroleum heavy oils such as normal pressure residual oil, vacuum residual oil, thermal decomposition residual oil, and various residual oils can be used. In addition, as the non-reactive heat carrier gas used as the heat carrier gas, inert gases such as steam, nitrogen, argon, etc., complete combustion gas that does not substantially contain oxygen, decomposition gas, gasification product gas, etc. may be used as appropriate. Ru. The thermal decomposition method for petroleum-based heavy oil is carried out in a series consisting of one heating furnace and a plurality of reactors. Petroleum-based heavy oil as a raw material is constantly heated in a heating furnace and poured into a first reaction can, and after the filling is finished, the switching valve is switched to pour it into a second reaction can, and then a plurality of reaction cans are sequentially filled. The mixture is continuously introduced again so as to return to the first reaction vessel. At this time, the heating time of the petroleum heavy oil in the heating furnace is 0.5 to 15 minutes, and the outlet temperature is set to 350 to 520°C. In addition, a non-reactive heating medium gas of 400 to 800℃ is blown into the reaction vessel from the bottom of the reaction vessel according to a predetermined flow rate program, and is brought into direct contact with the liquid phase petroleum heavy oil to achieve a reaction temperature of 400 to 440℃. The thermal decomposition reaction of petroleum-based heavy oil is carried out.
At this time, if high-temperature petroleum-based heavy oil or heat carrier gas is introduced into the reactor immediately, the reactor body will receive a sudden heat shock and the reactor material will become fatigued. A portion of petroleum-based heavy oil as a raw material (referred to as an initial charge) may be charged. The petroleum-based heavy oil charged into the reactor undergoes a thermal decomposition reaction over a charging time and a predetermined reaction time, and cracked gas, cracked oil, and pitch are produced by decomposition and polycondensation. The cracked gas and cracked oil are discharged from the top of the reactor during the reaction together with the heat carrier gas, and cracked oil is produced by separation and distillation. In addition, the petroleum-based heavy oil in the liquid phase of the reactor becomes pitch as the polycondensation progresses, and when the pitch reaches a predetermined softening point, the pitch is quenched to stop the reaction, and the pitch is melted from the bottom of the reactor. Take it out in good condition. In order to obtain cracked oil with the highest possible yield through thermal decomposition of petroleum-based heavy oil and to produce homogeneous pitches, the liquidus temperature is in the range of 400 to 440°C and the charging time is 0.5 to 4 hours. , reaction time after stakeout 10
Although good results have been obtained if the thermal decomposition reaction is carried out within a certain period of time, in order to further improve this process, it is important to control the rise in the liquidus temperature of the reactor at the initial stage. In other words, when high-temperature heavy petroleum oil starts to be introduced into the reactor, the liquidus temperature begins to rise, but
The thermal decomposition reaction is carried out so that this temperature rise falls within the range between the following equations. T _L =440−90exp(−0.085θ) () T _L =400−100exp(−0.085θ) () However, T _L : Liquidus temperature (°C), θ : Pumping time of heavy oil (minutes) Reaction The liquid phase temperature rise curve of the can is shown in Figure 1.
The horizontal axis is the filling time θ, the vertical axis is the liquidus temperature T _L ,
Equations and formulas are shown by curves and curves, respectively. The liquidus temperature rise is determined by the temperature and flow rate of the petroleum-based heavy oil introduced, and the temperature and flow rate of the non-reactive heating medium gas blown in, so these can be controlled. When the reaction vessel is initially charged, the temperature and amount of the initial charge may be controlled to match the above conditions. The liquidus temperature rise is determined by the formula θ at the start of the reaction.
The temperature starts from 350 to 300°C at θ = 0, increases relatively rapidly until 30 minutes, and then gradually increases to 440 to 400°C at θ = 40 to 60 minutes. Reaction time after switching the tension (for example, in the example operation described later)
In the case of No. 3, the reaction time is 50 minutes as shown in FIG. 1), the liquidus temperature becomes somewhat lower along the descending line determined by the heat balance. The reaction is stopped when the softening point of the produced pitch reaches the target value. The liquid phase temperature can be easily controlled by controlling the temperature and flow rate of the heavy petroleum oil and the temperature and flow rate of the heat carrier gas, but it is even easier to control it by performing an initial charge. It's easy. Note that FIG. 2 shows an example of the operation of blowing superheated steam as the heat medium gas. When the temperature is increased within the region A between the curves in FIG. 1, the amount of cracked oil produced increases and the properties of the resulting pitch become uniform. If the temperature is raised in region B higher than the curve, the properties of the resulting pitch will be non-uniform, for example, the softening point and quinoline insoluble content will vary greatly, and a large amount of coke will be produced, which will impede long-term industrial operation. . On the other hand, if the temperature is increased within the region C below the curve, the generation of cracked oil will be reduced. Differences in products depending on the temperature rise regions A, B, and C will be specifically shown in Examples below. The resulting cracked oil is rich in aliphatic hydrocarbons and is suitable as fuel oil. Regarding the yield of cracked oil, the rise in liquidus temperature is greater in region A than in region C, for example, there is a difference of 2% between region A of about 64% and region C of about 62%.
2% may seem small, but since heavy petroleum oil is generally processed in large quantities industrially, the production amount of cracked oil can be greatly increased. In addition, the resulting pitch is a polycyclic aromatic hydrocarbon, which has a higher softening point and less quinoline-insoluble content than coal tar-based pitch or general petroleum-based pitch, making it a good binder, such as non-viscous pitch. When a small amount of the pitch of the present invention is added as a binder to coke and coke is produced, it becomes coke for blast furnaces in steel manufacturing, and can also be widely used as a binder for carbon and ceramics. As mentioned above, the thermal cracking reaction method for petroleum-based heavy oil of the present invention can produce a large amount of cracked oil and produce a homogeneous pitch, and can be operated stably industrially, so it will greatly contribute to the energy industry. It is large. Examples of the present invention will be described below. Example A mixture of vacuum residues of Kafji crude oil and Gatsuchi Saran crude oil was used as feedstock (its properties are shown in Table 1) and heat treated at about 40 kg/H under four different conditions. The conditions for the heat treatment are shown in Table 2.

【table】

[Table] Raw material oil is stored in a tank preheated to 150℃, heated in a tubular heating furnace at the temperature shown in Table 2, and then
The mixture was introduced into a two-unit reactor system for thermal decomposition. Each reaction vessel had a cylindrical shape with a height of 2 m and an inner diameter of 300 mm, and was equipped with a stirrer at the bottom for stirring at 50 rpm.
The feedstock oil was continuously heat-treated by periodically repeating the process of charging the raw oil into one reaction can with flashing for 2 hours and then charging it into the other reaction can for 2 hours. The liquidus temperature curve of the reaction vessel is shown in FIG. Further, superheated steam was blown from the bottom of the reactor as shown in FIG. 2 to accelerate the reaction and cause the decomposition products to quickly overflow out of the reactor along with the steam, thereby obtaining cracked oil. The high boiling point fraction of the cracked oil is mixed with the raw material oil and supplied to the heating furnace as recycled oil. The ratio of this recycled oil to the raw material oil is called the recycling ratio. Even after the stakeout is over, a certain period of time (this time,
The superheated steam (referred to as reaction time) was supplied to allow the reaction to proceed, and when the contents of the reaction can (referred to as pitch) reached a predetermined softening point, the pitch was rapidly cooled and taken out. Operation No. 1 is shown in Figure 1b, in which the reactor liquid phase temperature passes through region B, which is higher than the formula, and operation No. 2 and No. 3 are carried out in region A, which is between the formula of the present invention and the formula. Figure 1a
-1, a-2, Operation No. 4 was the case of Fig. 1 c, which passed through region C lower than the formula.

【table】

[Table] As is clear from Tables 3 and 4, operation No. 1
The pitch of No. 2 contained a large amount of quinoline insoluble matter itself, and the size of the optically anisotropic substance usually called mesophase dispersed in the pitch was larger than that of No. 2 to No. 4, and in this sense, the pitch was nonuniform. . The size of this mesophase is not only important in handling the molten pitch, but also has a large effect on coking inside the reaction vessel. That is, in No. 1 operation, after 10 consecutive batches of operation, the coke thickness on the inner wall of the reactor was measured after opening and the average thickness was 2.2 mm/batch, and compared to Nos. 2 to 4, the coke precipitation rate was was large, and long-term stable operation became a problem. In comparison, under other conditions, the mesophase size was small and the coke precipitation rate was slow. The results of Operation No. 4 showed that there was no problem with the pitch quality, but the cracked oil yield was low and the economy was poor. Operations No. 2 and No. 3 are standard operations, and can be said to be desirable examples from the viewpoint of both pitch homogeneity and product yield.

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a diagram showing the liquidus temperature of the reaction vessel, and FIG. 2 is a diagram showing the flow rate of superheated steam blown corresponding to Example Operation No. 3. A, B, C...area, p...maximum flow rate.

Claims (1)

[Claims] 1. Using a series consisting of one heating furnace and a plurality of reaction vessels, petroleum-based heavy oil is poured from the heating furnace into the first reaction vessel, and after completion of the heating, it is poured into the second reaction vessel. At the same time, a non-reactive heating medium gas is blown into each reaction vessel from the bottom of the reaction vessel and the non-reactive heating medium gas is brought into direct contact with petroleum-based heavy oil to cause a thermal decomposition reaction. The liquidus temperature of the reactor during the charging period is calculated using the following formula: T _L = 440−90exp (−0.085θ) () T _L = 400−100exp (−0.085θ) () However, T _L ; liquidus temperature A method for pyrolysis treatment of petroleum-based heavy oil to produce cracked oil and aromatic pitch, characterized by raising the temperature to a range between (°C) and θ: time (minutes).