JPH0535754B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for removing iron contained in residual oil distilled under normal pressure or under reduced pressure (hereinafter referred to as petroleum mineral oil fraction). [Prior Art and Problems to be Solved by the Invention] Fractional distillation of crude oil to separate it into volatile oil fraction, kerosene fraction, gas oil fraction, and atmospheric residue fraction is common in the oil refining industry. is being carried out. These petroleum hydrocarbon fractions are each refined into petroleum products such as volatile oil, kerosene, light oil, and heavy oil. The most commonly used refining method at present is a method in which hydrogen and petroleum hydrocarbon fractions are reacted in the presence of a catalyst at high pressure and temperature, ie, a method collectively referred to as a hydrorefining method. The impurities contained in the petroleum fraction that is the raw material for the hydrorefining process often do not contain iron, or even if they do, the concentration is extremely low. (e.g. 1ppm or less)
It is. However, raw distillate oil containing iron content of 1 ppm or more may be obtained, and some such raw material oils may contain iron content of 100 ppm or more. In many cases, such feedstock oil has a high acid value, and at least a portion of the iron contained therein is corroded by acidic substances in distillation equipment, distillate storage tanks, oil transmission pipes, etc. It is thought that it was dissolved in the oil. When such raw materials containing a large amount of iron are processed by the hydrorefining method, troublesome problems arise in the operation of the refining equipment. In other words, since these iron-containing compounds are dissolved in the feedstock oil, they are not collected by the filter installed at the entrance of the equipment and enter the equipment, reaching the reaction tube, which is an important part of the equipment, where they are chemically processed. It undergoes a reaction and is decomposed. Iron is a form of sulfide that accumulates between catalyst particles inside the reactor, clogging the reactor, or adheres to the surface of catalyst particles, reducing the performance of the catalyst. When processing such feedstock oils, it is known that it is effective to manufacture distillation equipment, distillate oil storage tanks, piping, etc. from corrosion-resistant materials, and to line their interiors with corrosion-resistant materials. ing. However, this method tends to be expensive as it requires corrosion-resistant measures for huge storage tanks and long oil pipes. Another method is to provide a guard reactor in the earth stream of the reactor of a hydrorefining device. In this method, the feedstock is led to a reactor called a guard reactor, where iron compounds dissolved in the oil are decomposed by a chemical reaction. The iron content is converted into sulfide, captured by the filler and catalyst particles filled inside the guard reactor, and deposited inside the guard reactor. The raw oil from which the iron content has been removed in this way exits the guard reactor and is then led to the reactor. Although this method prevents clogging of the reactor and deterioration of its catalyst, clogging of the guard reactor and deterioration of the catalyst filled in the guard reactor due to iron compounds are unavoidable. Another method is to treat distillate oil containing iron with an aqueous sodium hydroxide solution, neutralize acidic substances in the oil, and extract it into the aqueous solution. In this method, iron aggregates as a hydroxide or oxide and either moves into the aqueous solution or is collected at the interface between the aqueous solution phase and the oil phase. This method is used to extract naphthenic acid from petroleum fractions containing naphthenic acid, and is advantageous if the recovered naphthenic acid has commercial value. However, although this method is not infeasible when the viscosity of the feed oil fraction is low, such as spindle oil fractions, it is difficult to separate the oil phase and the aqueous phase with high viscosity oils, and the naphthene Extraction of the acid salt into an aqueous solution is also unfeasible and cannot be carried out. Another method is to contact petroleum-based mineral oil with hydrogen sulfide or ammonia to change the iron content in the mineral oil into oil-insoluble iron compounds, and remove these iron compounds by filtration, centrifugation, etc. Particles that precipitate in mineral oil systems are mainly 10 microns or less, and sometimes significantly less than 1 micron, so they cannot be removed with ordinary fine-mesh filters. The use of membranes, filter paper, etc. can be considered for this purpose, but for large-scale processing, there are problems such as increased pressure loss due to clogging and replacement, so even if they can be used for laboratory-level processing, they are not of practical use. It is possible. Another method is centrifugation, but this is also impractical from the viewpoint of structure and operation. On the other hand, a large amount of fine particles made of iron or iron compounds are contained as iron in the residual oil after distillation under normal pressure or under reduced pressure. When crude oil is transported by tanker from the production area, stored in tanks, and sent to distillation equipment via oil pipes, etc., these substances become mixed in due to wear from the tanks, lines, and equipment. When such distillation residue oil is used as a feedstock for a fixed-bed hydrotreating unit, fine particulate iron contained in the feedstock accumulates on the catalyst or between catalyst particles in the reactor, causing a reaction. This may clog the vessel or reduce the activity of the catalyst particles. Among these, blockage of the reactor causes an increase in pressure,
Occasionally, the equipment must be shut down, resulting in extremely large losses. Therefore, if it is possible to remove fine particles made of iron, there will be a great advantage. However, the fine particles are extremely small, on the order of 0.1 to 20 microns, and cannot be removed by filters generally used in the petroleum refining industry. In addition to the methods described above, there are several methods for removing the particles. For example, using a fine-mesh filter such as filter paper or membrane filter. However, such filters have extremely large pressure losses and are prone to clogging, making them difficult to use for long periods of time, and even if they are replaced, they are completely unsuitable for processing large quantities of raw oil due to operational reasons. Another method is to use centrifugation equipment. However, this also has a problem with the throughput from the viewpoint of structure and operation, and is of little practical use. [Means for Solving the Problems] As a result of intensive studies by the present inventors to solve the above-mentioned problems, the present inventors found that it is possible to separate the iron by using a high gradient magnetic separator. Moreover, they discovered that the processing capacity was extremely large, and completed the present invention. In other words, the present invention reduces iron content.
Normal pressure or vacuum distillation residual oil containing 5ppm or more
Treated with a high gradient magnetic separator under conditions consisting of a magnetic field strength of 500 to 25,000 Gauss, a temperature of 100 to 350°C, and a linear velocity of 0.1 to 50 cm/sec to separate and remove iron.
The iron content in normal pressure or vacuum distillation residue is characterized by reducing the pressure drop of the fixed bed hydrotreating equipment by supplying the magnetically treated oil to the fixed bed hydrotreating equipment and hydrogenating it. Regarding the removal method. The raw material used in the present invention is a petroleum-based mineral oil fraction containing 5 ppm or more of iron. The above-mentioned iron includes those soluble in mineral oil as described above, and fine particles of iron or iron compounds. The petroleum-based mineral oil referred to in the present invention includes various petroleum-based crude oils, various distillate oils obtained by distilling the same under normal pressure or reduced pressure, and those obtained by subjecting these fractions to solvent dewaxing treatment. be able to. In the present invention, 10% of these mineral oils
The usefulness increases when using a relatively heavy fraction with a distillation point of 280°C or higher in terms of normal pressure. Further, the present invention is more effective when the distillate obtained by distillation is directly subjected to the treatment of the present invention without undergoing the above-mentioned refining treatment. In the present invention, these mineral oils contain a small amount of soluble iron, such as 1 ppm, to a relatively large amount, such as 500 ppm, usually 5 to 50 ppm.
Items containing 200ppm are subject to the target. In general, some South American crude oils contain relatively large amounts of iron, and mineral oils made from these raw materials can be effectively processed in the present invention. In addition, as the petroleum-based mineral oil referred to in the present invention, it is possible to use normal pressure or vacuum distillation residue oil obtained by distilling various petroleum-based crude oils at normal pressure or reduced pressure, as well as deasphalt oil of these fractions. can. These distillation residue oils contain large amounts of impurities such as metals such as iron, nickel, and vanadium, sulfur, nitrogen, and asphaltene. Furthermore, fine particles made of iron and iron compounds (FeO, Fe ₂ O _3, etc.) are mixed into these distillation residue oils during transportation and storage. These fine particles are concentrated in the distillation residue oil, so the concentration in the distillation residue oil is 10%.
It can reach ~100wt ppm. The particle size of the fine particles ranges from 0.1 to 100 microns, but most of them are extremely small, 20 microns or less. The high gradient separator used in the present invention is a ferromagnetic packing placed in a uniform high magnetic field space, and a magnetic field is applied around the packing, usually 100×10 ³ to 20.000×10 ³ Gauss/
It was designed to magnetize ferromagnetic or paramagnetic particles on the surface of the filling by creating a magnetic field gradient as high as cm, and to separate them from weakly paramagnetic or diamagnetic particles. It is a magnetic separator. The above-mentioned ferromagnetic filler is usually 1-
An aggregate of ferromagnetic fine wires such as steel wool or steel net having a diameter of 1000 μm, expanded metal, steel beads, etc. are used. Preferably, expanded metal or steel beads are used. High gradient magnetic separators include an electromagnetic type that generates a uniform high magnetic field using an excitation coil, and a permanent magnet type that generates a uniform high magnetic field using a permanent magnet. Next, the method of the present invention will be described. A method for removing iron in a petroleum mineral oil fraction using a high gradient magnetic separator is to introduce the mineral oil fraction into the magnetic field space of the high gradient magnetic separator, and to introduce the mineral oil fraction into a ferromagnetic packing placed in the magnetic field space. The purpose is to magnetize and remove the iron. Variables when operating a high gradient magnetic separator include magnetic field strength, linear velocity, and processing temperature, and the optimal conditions are selected depending on the type, size, concentration, etc. of the particles to be magnetized. Magnetic field strength is the strength of the magnetic field in the space in which the filling is placed, usually 500 to 25000 Gauss, preferably
It ranges from 1000 to 20000 Gauss. Processing temperature refers to the temperature of the oil when it is introduced into the high gradient magnetic separator, and is usually between room temperature and 400°C, preferably between room temperature and 250°C. Particle concentration is the concentration of iron compound particles contained and suspended in oil, and is usually 0.001g/
~10g/approximately. Moreover, the linear velocity is the linear velocity of oil when passing through a magnetic field space, and is usually 0.1/sec to 50 cm/sec, preferably 0.2 cm/sec to 20 cm/sec. The smaller the magnetism of the particles to be separated or the smaller the particle size, the smaller the linear velocity needs to be. On the other hand, drum-type magnetic separators, which have traditionally been used to separate relatively large ferromagnetic particles in magnetic beneficiation of iron ore, have a magnetic field strength of 500 Gauss and a magnetic field distribution of approximately 500 Gauss/cm. Therefore, the magnetic field strength and magnetic field gradient of the high gradient magnetic separation referred to in the present invention are significantly smaller, and such a drum type magnetic separator has a large particle diameter that can be mixed into the catalyst as an impurity due to corrosion or wear of the equipment. It is possible to remove 0.1 iron powder contained in petroleum-based mineral oil fractions.
It cannot be used to separate iron particles of ~20 microns. In the present invention, a petroleum-based mineral oil fraction from which iron has been separated and removed can be subjected to fixed-bed hydrotreating. Fixed bed hydrotreating is a method in which raw oil and hydrogen are reacted at high temperature and pressure in the presence of a catalyst to perform dehydration, desulfurization, and demetalization reactions to convert it into useful oil.Direct desulfurization and hydrogenation Refers to decomposition, etc. Hydrotreating catalysts include cobalt-molybdenum, nickel-molybdenum, nickel-tungsten, cobalt-molybdenum-nickel, or platinum on porous supports such as activated alumina, silica-alumina, and silica-magnesia catalysts. and/or a catalyst supporting a hydrogenation metal component consisting of a group metal or metal compound is used. Conditions for the hydrogen treatment step include reaction temperature of about 300 to 480°C, reaction pressure of about 50 to 200 Kg/cm ² (gauge), preferably about 75 to 150 Kg/cm ² (gauge), and liquid hourly space velocity of about 0.1 to 10 HR ^-1. , preferably about 0.2~
4HR ^-1 and hydrogen/oil ratio of approximately 100 to 200 N/are respectively adopted. In the present invention, petroleum-based mineral oil is brought into contact with hydrogen sulfide or a gas containing hydrogen sulfide and ammonia, the iron contained in the petroleum-based mineral oil is changed into an insoluble iron compound, and the compound is separated from the petroleum-based mineral oil using a high gradient magnetic separator. can be separated and removed. As hydrogen sulfide gas and ammonia gas in the present invention, pure gases may be used, respectively, but a mixture diluted with hydrogen, nitrogen, or an inert gas such as methane may also be used. In the present invention, exhaust gas (off gas) commonly obtained in the oil refining industry can be effectively used as the gas to be brought into contact with the iron-containing petroleum mineral oil. In other words, the catalytic hydrorefining method, which is a currently common method for refining various petroleum hydrocarbon fractions, hydrotreats mineral oil, but in this case, The sulfur and nitrogen compounds react with hydrogen in the presence of a catalyst at high pressure and temperature, and are discharged from the hydrorefining reactor as hydrogen sulfide gas and ammonia gas, respectively, along with unreacted hydrogen and lower hydrocarbons. be done. In the present invention, gaseous substances discharged from the hydrorefining reaction apparatus as they are, or gases discharged when gas and liquid are separated from the reaction mixture from the reactor using a high-pressure separation apparatus and/or a low-pressure separation apparatus,
Alternatively, gas discharged when refined oil is stripped to remove residual gas can be effectively used as the mixed gas of hydrogen sulfide gas and ammonia gas in the present invention. It goes without saying that hydrogen sulfide and ammonia in such a mixed gas are preferably used when their temperature falls within the above-mentioned range; It can also be used in addition. First, contact between hydrogen sulfide or a gas containing hydrogen sulfide and ammonia and a petroleum-based mineral oil fraction can be carried out using a gas-liquid mixing contact device such as a packed tower, a bubble tower, or an orifice mixer, and the time required for this is A range of 1 minute to 120 minutes is sufficient. The contact temperature is usually in the range of 10°C or more and 300°C, preferably room temperature to 200°C; even if it is carried out at a higher temperature, the iron removal rate does not improve but rather decreases. The amount of gas used in the contacting process of the present invention is such that the amount of hydrogen sulfide is usually from 1 to 1000 moles, preferably from 5 to 600 moles, per gram of iron contained in the mineral oil being treated. In addition, when ammonia gas is mixed with hydrogen sulfide, the amount of ammonia gas is usually 1/2 mole or less, preferably 1/5 to 1/1000 per mole of hydrogen sulfide gas.
It is a mole. The amount of gas used can be reduced by using a device with high contact efficiency. Mineral oil containing iron is brought into contact with a gas containing hydrogen sulfide and ammonia at a temperature of 10°C to 300°C to convert the iron into insoluble iron compounds, which precipitate and suspend in the oil. This insoluble iron compound is rich in iron sulfide, but is not decomposed by acidic substances in the oil. The particle size of the insoluble iron compound is usually 10 μm.
The following are the main types, sometimes much less than 1 μm, and usually exist in a suspended state in oil. Next, insoluble iron compounds precipitated and suspended in the oil are removed by a high gradient magnetic separator. In the present invention, after bringing the petroleum-based mineral oil fraction into contact with hydrogen sulfide or a gas containing hydrogen sulfide and ammonia, it can be treated with a high gradient magnetic separator and further subjected to fixed bed hydrogenation treatment. Preferred embodiments of the present invention will be explained below with reference to the drawings. In FIG. 1, 1 is a high gradient magnetic separator. 2 to 6 are on-off valves, and 7 to 11 are lines. Here, the petroleum-based mineral oil fraction introduced from line 7 is introduced into high gradient magnetic separator 1. At this time, valves 4, 5, and 6 are closed, and valves 2 and 3 are open. A portion of the iron is magnetized in the filling placed in the magnetic field space 1. If the operation is continued for a long period of time, the number of magnetized substances in the first filling may increase, and the iron removal rate may decrease. In that case, valves 2 and 3 are closed and valve 4 is opened to bypass the petroleum-based mineral oil fraction. Then valves 5 and 6
is opened, cleaning oil is flowed from the normal line 9 in the opposite direction to that during processing at a high linear velocity, preferably at least 10 times that during processing, and immediately after that, the magnetic field is turned off. By this operation, the fine particles that have been magnetized in the filling are washed away and discharged through line 10. After a short period of time, the flow is returned to its original state and the treatment operation is repeated. In FIG. 2, 1 in the figure is a high gradient magnetic separator, 1
2 is a hydrotreating device. 2 to 6 are on-off valves, and 7 to 11 are lines. Here, the petroleum-based mineral oil fraction introduced from line 7 is introduced into high gradient magnetic separator 1. At this time, valves 4, 5, and 6 are closed, and valves 2 and 3 are open. A portion of the iron content is magnetized in the packing placed in the magnetic field space 1, and the petroleum-based mineral oil fraction with the reduced iron content is sent to the hydrotreater 12 through the line 11. If the operation continues for a long time, the number of magnetized substances in the first packing may increase, and the removal rate of the particles may decrease. In that case, valves 2 and 3 are closed and valve 4 is opened to bypass the petroleum-based mineral oil fraction. Then valves 5 and 6
is opened, cleaning oil is flowed through line 9 in the opposite direction to that during processing at a high linear velocity, preferably at least 10 times that during processing, and immediately after that, the magnetic field is turned off. By this operation, the fine particles that were magnetized in the filling are washed away,
It is discharged through line 10. After a short period of time, the flow is returned to its original state and the treatment operation is repeated. In FIG. 3, 13 is a gas and oil contactor;
1 is a high gradient magnetic separator. 2 to 6 are on-off valves, and 7 to 11 are lines. Here, the feedstock oil introduced from line 7 is combined with the gas from line 14.
3, and an insoluble iron compound is precipitated. 8
is a bypass line and the valve is normally closed. After contact with the gas, the oil is sent to a high gradient magnetic separator for processing. The deposited iron and other iron are magnetized into a filling placed in one magnetic field space. After long-term operation, the charge may have an increased amount of magnetized iron, which may reduce the iron removal rate. In that case, valves 2 and 3 are closed and valve 4 is opened to bypass the feedstock oil. After that, valves 5 and 6 are opened, and cleaning oil is flowed from line 9 preferably in the opposite direction to that during processing at a relatively high linear velocity, preferably at least 10 times the linear velocity during processing, and immediately after flowing, the magnetic field is cut.
There, the compound magnetized in the filling is washed and discharged together with the cleaning oil through line 10. The processing operation is then repeated again. Example 1 The present invention will be explained in detail by the following example.
Petroleum vacuum residue oil was treated using an electromagnetic high gradient magnetic separator under the following conditions. Magnetic field strength: 20 kilogauss Linear velocity: 3.0 cm/sec Temperature: 150°C Filler: Steel wool The iron content of the treated oil and raw material oil thus obtained was determined. The results are shown in Table-1.

[Table] Furthermore, using each of the oils shown in Table 1, Mo, Co, and Ni were added to the alumina carrier at 5wt each.
% supported catalyst was used for hydrogen treatment. The conditions are as follows. Reaction temperature: 400℃ LHSV: 0.3hr ^-1 Hydrogen partial pressure: 120Kg/cm ² Reaction time: 4000 hours After the reaction, the catalyst and deposits in each reactor are taken out from the top, middle, and bottom of the reaction tower, and calcined. After that, the total amount of Fe in the catalyst and deposits was measured.
The results are shown in Table-2.

[Table] As shown in Table 2, it can be seen that when oil treated with a high gradient magnetic separator is used as a raw material, the amount of iron in the catalyst bed at the top of the reaction tower is significantly reduced. Example 2 Commercially available iron naphthenate was dissolved in 70 pail fraction,
The raw material oil had an iron content of 100 ppm. A packed tower was used as the contact treatment equipment. The packed tower was ID75φ x 2000 mm, and 5.0 porcelain Raschig rings (diameter 10 mm) were used as the filling material. The raw material oil at room temperature (supply rate 5/hr) flows down from the top of the packed column, and the off-gas from the hydrorefining unit having the composition below at room temperature (supply rate 100-STP/hr) rises from the bottom of the column. hr) at room temperature and pressure, and then extracted from the bottom of the tower. Hydrogen (vo%) 73.8 Hydrogen sulfide (vo%) 2.1 Ammonia (vo%) 0.01 Light saturated hydrocarbons (vo%) (c ₁ - _{c 4} ) 24.09 The treated oil thus obtained was subjected to a high gradient magnetic separator. The treatment was carried out under the following conditions. Magnetic field strength: 10 kilogauss Linear velocity: 10 cm/sec Temperature: Room temperature Filling in magnetic field space: Steel wool Comparative Example 1 The treated oil obtained in Example was filtered through No. 5C filter paper. Comparative Example 2 The treated oil obtained in Example was centrifuged to separate solids in the oil. The oils obtained in the above Examples and Comparative Examples were analyzed, and the removal rate was calculated from the iron concentration. The results are shown in Table 3.

[Table] Example 3 Petroleum-based vacuum residual oil was treated using a permanent magnet type high gradient magnetic separator under the following conditions. Magnetic field strength: 1 kilogauss Linear velocity: 0.5 cm/sec Temperature: 250°C Filler: steel beads The iron content of the treated oil and raw oil thus obtained was determined. The results are shown in Table-4.

[Table] Even when a permanent magnet type high gradient magnetic separator is used, the iron removal effect is almost the same as that of an electromagnetic type high gradient magnetic separator. [Effect of the invention] As described in Example 1, if the feedstock oil is reacted without being treated, a large amount of iron will precipitate on the top of the catalyst bed of the reactor, causing blockage, etc., and increasing the pressure. bring. This sometimes causes the equipment to stop, resulting in a major disadvantage. According to the present invention, the above-mentioned troubles can be prevented and the equipment can continue to operate until the catalyst loses its activity or as originally planned. As shown in Table 3, it can be seen that the method of the present invention improves the iron removal rate compared to the comparative example. In addition, the method of the present invention allows extremely rapid separation and removal, and the processing speed was several thousand times faster than that of the comparative example.

[Brief explanation of the drawing]

The attached drawings 1 to 3 are flow sheets of the method of the present invention. 1...High gradient magnetic separator, 2-6...Valve,
7...Raw material line, 8...Bypass line, 9~
10...Cleaning line, 11...Processing oil line, 1
2...Hydrotreater, 13...Gas and oil contactor, 14...Gas introduction line.

Claims (1)

[Claims] 1. Normal pressure or reduced pressure distillation residual oil containing 5 ppm or more of iron is subjected to a magnetic field strength of 500 to 25,000 Gauss, 100 to
The oil is treated with a high gradient magnetic separator at a temperature of 350°C and a linear velocity of 0.1 to 50 cm/sec to separate and remove iron, and the magnetically treated oil is fed to a fixed bed hydrotreater for hydrogenation. A method for removing iron from residual oil from normal pressure or vacuum distillation, characterized by reducing pressure loss in the fixed bed hydrotreating apparatus. 2. Contact the residual oil from normal pressure or vacuum distillation with hydrogen sulfide or a gas containing hydrogen sulfide and ammonia to convert the soluble iron contained in the residual oil into an insoluble iron compound, and then perform high gradient magnetic separation. The method according to claim 1, characterized in that the treatment is carried out by a machine. 3. The method according to claim 1 or 2, wherein the high gradient magnetic separator is of an electromagnet type or a permanent magnet type.