JP2009221300A - Method for eliminating magnetic particle in ft synthetic oil - Google Patents

Abstract

An object of the present invention is to reduce the concentration of magnetic particles contained in a Fischer-Tropsch synthetic crude oil, thereby suppressing a decrease in washing efficiency of the magnetic separation process and increasing the separation efficiency of the magnetic particles. A manufacturing method is provided.
FT synthetic crude oil synthesized in a reactor 10 is liquid-solid separation means by a liquid-solid separator 20 provided separately as a pretreatment in a magnetic separation step, and solids such as catalyst particles and liquid The liquid component containing hydrocarbon particles is separated into liquid components containing hydrocarbons, and subsequently the liquid components containing catalyst particles that could not be separated by the liquid-solid separator 20 in the high gradient magnetic separator 30 are separated into solid components such as catalyst particles by the magnetic separation means. And magnetically separated into liquid containing liquid hydrocarbons.
[Selection] Figure 1

Description

  In the present invention, magnetic particles contained in FT synthetic crude oil obtained by a Fischer-Tropsch synthesis method (hereinafter abbreviated as “FT synthesis method”) using carbon monoxide and hydrogen as raw materials are separated by a magnetic separator. Regarding the method.

  In recent years, clean liquid fuels that are low in sulfur content and aromatic hydrocarbon content and that are friendly to the environment have been demanded from the viewpoint of reducing environmental impact. Therefore, in the petroleum industry, an FT synthesis method using carbon monoxide and hydrogen as raw materials is being studied as a method for producing clean fuel. According to the FT synthesis method, a liquid fuel base material having a high paraffin content and not containing a sulfur content, for example, a diesel fuel base material can be produced. For example, environmentally-friendly fuel oil is also proposed in Patent Document 1.

JP 2004-323626 A

On the other hand, FT synthesis catalysts using carbon monoxide and hydrogen as raw materials have hitherto been many iron-based solid catalysts, but recently, cobalt-based solid catalysts have also been developed because of their high activity.
Here, the reaction form of the FT synthesis method may be a fixed bed, a fluidized bed, a moving bed or the like, but anyway, a heterogeneous catalyst which is a solid catalyst is used.
The resulting FT synthetic crude oil contains a considerable amount of residual catalyst.
The obtained FT synthetic crude oil is subjected to a purification process such as distillation and hydrotreating to become a product such as a fuel oil. However, the residual catalyst affects subsequent processing steps, for example, the purification process. Need to be removed.

Although the residual catalyst in the FT synthetic crude oil depends on the reaction form of FT synthesis, it is often fine particles, and it is advantageous to separate this by magnetic separation.
That is, magnetic separation is used to process and remove magnetic particles from a FT synthetic crude oil with a high gradient magnetic separator. This method places a ferromagnetic packing in a uniform high magnetic field space generated by an external electromagnetic coil, and the surface of the packing is made ferromagnetic by a high magnetic field strength of typically 10,000 to 50,000 gauss that occurs around the packing. Alternatively, it is a magnetic separator designed to deposit paramagnetic particulate matter, separate them, and wash the adhered particles. Cleaning is performed by a cleaning liquid introduction line for intermittently cleaning the captured magnetic particles and a line for discharging the cleaned cleaning liquid.

However, the fine particles in the FT synthetic crude oil are fine and the amount thereof is large, so that the frequency of washing the packing is increased.
In other words, when the magnetic separator is introduced into the untreated FT synthetic crude oil after the FT synthesis reactor, the FT slurry is directly processed by the magnetic separator, and the collection efficiency immediately decreases due to the high catalyst concentration. The interval between intermittent cleanings must be shortened, which is inefficient.

  The present inventors have provided a separate liquid-solid separation step before the magnetic separation step by the high gradient magnetic separator, thus making it possible to lengthen the intermittent cleaning interval in the magnetic separation step.

  That is, according to the first aspect of the present invention, in the synthetic oil production method in which the FT synthetic crude oil obtained by the FT synthesis method is processed in a purification step including distillation, the captured magnetic particles are intermittently introduced before the purification step. A magnetic separation step for capturing and removing residual magnetic particles by a high gradient magnetic separator having a washing liquid introduction line for washing and a line for discharging the washed washing liquid is provided, and a separate pretreatment for the magnetic separation step is provided. It is related with the manufacturing method of the said synthetic oil characterized by providing a liquid-solid separation process.

  A second aspect of the present invention is the liquid-solid separation step using any one selected from a filter, a gravity sedimentation separator, a cyclone, and a centrifuge as the liquid-solid separation step as the pretreatment in the first aspect of the present invention. The present invention relates to a method for producing a synthetic oil.

When the magnetic separator is introduced into the FT synthetic crude oil after the FT synthesis reactor, the FT slurry is directly processed by the magnetic separator, and the collection efficiency decreases immediately due to the high catalyst concentration. This is inefficient because it is necessary to shorten the interval.
However, by reducing the catalyst concentration in a liquid-solid separation process such as filter and gravity sedimentation separation in advance before magnetic separation, the intermittent cleaning interval of the magnetic separator can be increased and the efficiency can be increased. .

The present invention is described in detail below.
Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, a synthesis gas containing carbon monoxide gas and hydrogen gas is supplied from a line 1, and liquid hydrocarbons are generated by an FT synthesis reaction in an FT synthesis reactor 10. The synthesis gas can be obtained by, for example, hydrocarbon reforming as appropriate. Typical hydrocarbons include methane, natural gas, LNG (liquefied natural gas), and the like. For example, a partial oxidation reforming method (POX) using oxygen, an autothermal reforming method (ATR) that is a combination of the partial oxidation reforming method and the steam reforming method, a carbon dioxide gas reforming method, or the like can be used. .

Next, the FT synthesis process will be described with reference to FIG.
FT synthesis comprises an FT synthesis reactor 10. The reactor 10 can be, for example, a bubble column reactor, which is an example of a reactor that synthesizes synthesis gas into liquid hydrocarbons, and synthesizes liquid hydrocarbons from synthesis gas by an FT synthesis reaction. Functions as a reactor for FT synthesis.

The main body of the reactor 10 is a substantially cylindrical metal container having a diameter of about 1 to 20 m, preferably about 2 to 10 m. The height of the reactor body is about 10 to 50 m, preferably about 15 to 45 m. Inside the reactor main body, a slurry in which solid catalyst particles are suspended in liquid hydrocarbon (product of FT synthesis reaction) is accommodated.
From the middle of the reactor, a part of the slurry is discharged from the line 3 to the separator 20. From the top of the column, unreacted synthesis gas or the like is discharged in line 2, and a part thereof is appropriately circulated to the reactor.

  The synthesis gas supplied from the outside through the synthesis gas supply pipe 1 is injected into the slurry inside the reactor 10 from a synthesis gas supply port (not shown). The synthesis gas undergoes a liquid hydrocarbon synthesis reaction (FT synthesis reaction) by a contact reaction that contacts catalyst particles. Specifically, as shown in the chemical reaction formula (1) below, hydrogen gas and carbon monoxide gas cause a synthesis reaction.

2nH ₂ ten _{nCO → (-CH 2 -) n} + nH 2 0. . . . (1)

Specifically, the synthesis gas flows into the bottom of the reactor 10 and raises the slurry stored in the reactor. At this time, in the reactor, carbon monoxide and hydrogen gas contained in the synthesis gas react by the above-described FT synthesis reaction to generate hydrocarbons. Furthermore, although heat is generated during this synthesis reaction, the heat is removed by an appropriate cooling means.
The metal catalyst includes a supported type and a deposited type. In any case, the metal catalyst is a solid particle containing an iron group metal. An appropriate amount of metal is contained in the solid particles, but 100% metal may be used. The iron group metal is exemplified by iron, and cobalt is preferable from the viewpoint of high activity.

The composition ratio of the synthesis gas supplied to the FT synthesis reactor 10 is adjusted to a composition ratio (for example, H ₂ : CO = 2: 1 (molar ratio)) suitable for the FT synthesis reaction. In addition, the synthesis gas supplied to the reactor 10 is pressurized to a pressure (for example, 3.6 MPaG) appropriate for the FT synthesis reaction by an appropriate compressor (not shown). However, the compressor may not be provided.

Thus, the liquid hydrocarbon synthesized in the reactor 10 is taken out from the reactor 10 as a slurry in which catalyst particles are suspended from the line 3 in the middle of the reactor 10 and introduced into the separator 20. In the separator 20, the taken slurry is separated into a solid content such as catalyst particles and a liquid content containing liquid hydrocarbons by liquid-solid separation means. This liquid-solid separation means can be performed by a conventionally known conventional method. Preferably, a filter using an appropriate filter such as a sintered metal filter, for example, a gravity sedimentation separator of a natural sedimentation system, a cyclone, a centrifuge, and the like can be exemplified.
Subsequently, in the high gradient magnetic separator 30, the liquid content containing the catalyst particles that could not be separated by the separator 20 is magnetically separated into the solid content such as catalyst particles and the liquid content containing liquid hydrocarbons by the magnetic separation means. .
The magnetic separation process will be described below.

  That is, in the high gradient magnetic separator 30, the FT synthetic crude oil is processed to separate and remove the magnetic particles from the line 34, and the separated FT synthetic crude oil is guided from the line 33 to the rectifying column 40. It has also been found that the iron group metal as the FT synthesis catalyst has a certain magnetic susceptibility and exhibits paramagnetism, whether iron or cobalt. Therefore, removal by magnetic separation is quite effective.

  The high gradient magnetic separator 30 used in the present invention has a ferromagnetic packing disposed in a uniform high magnetic field space generated by an external electromagnetic coil, and is usually 1 to 20 kGauss / cm generated around the packing. A magnetic separator designed to attach ferromagnetic or paramagnetic particulate matter to the surface of the packing by a high magnetic field gradient, separate them, and wash the attached particles. For example, as the high gradient magnetic separator, a commercially available machine known by a registered trademark “FEROSEP” or the like can be used.

  As the ferromagnetic filler, an aggregate of ferromagnetic fine wires such as steel wool or steel net having a diameter of 1 to 1000 μm, an expanded metal, and a shell-like metal strip are usually used. As the metal, stainless steel having excellent corrosion resistance, heat resistance and strength is preferable.

  In addition, as proposed in JP-A-7-70568, a ferromagnetic metal piece is a plate-like body having two surfaces, and the area of the larger surface of the two surfaces is the diameter. R = equal to the area of a circle of 0.5 to 4 mm, the ratio of R to the maximum thickness d of the plate, R / d is in the range of 5 to 20, and the plate is mainly made of Fe A ferromagnetic metal piece made of an Fe—Cr alloy containing 5 to 25 wt% of Cr, 0.5 to 2 wt% of Si, and 2 wt% or less of C as components can also be preferably used.

  The step of separating the magnetic particles in the liquid component containing the catalyst particles that could not be separated by the separator 20 with the high gradient magnetic separator 30 introduces the liquid component into the magnetic field space of the high gradient magnetic separator 30; Magnetic particles are attached to the ferromagnetic packing placed in the magnetic field space and removed from the liquid. Next, in the step of washing and removing the magnetic particles trapped in the packing, there is a limit to the amount of magnetic particles that can be trapped in the packing of a certain area. The magnetic particles are washed away from the packing. This washing and removing step is performed by cutting off the magnetic field to desorb the magnetic particles, and discharging the magnetic particles out of the magnetic separator with the washing liquid. The magnetic separation conditions for the magnetic particles contained in the liquid and the washing and removal conditions for the magnetic particles trapped and adhered to the packing will be described below.

  As a separation condition of the high gradient magnetic separator 30, the magnetic field strength is preferably 10,000 Gauss or more, and more preferably 25000 Gauss or more. The liquid temperature (treatment temperature) in the separator is preferably from 100 ° C. to 400 ° C., more preferably from 100 ° C. to 300 ° C., particularly preferably from 100 ° C. to 200 ° C. The liquid residence time (residence time) is preferably 15 seconds or longer, and more preferably 30 seconds or longer.

  Next, when the magnetic separation operation of the magnetic particles is continued, the removal rate decreases as the amount of the magnetic particles trapped in the packing increases. Therefore, in order to maintain the removal rate, a washing and removing step of discharging the captured magnetic particles to the outside of the magnetic separator after passing through oil for a certain time is required. In actual industrial operation, the magnetic particle-containing liquid may bypass the magnetic separator during the washing and removing process. However, if the washing time is long, the amount of magnetic particles flowing into the rectifying column 40 increases. Therefore, a preliminary separator for switching may be provided as necessary.

  The washing liquid used for washing and removal is not particularly limited, but the FT synthetic crude oil treated by the magnetic separator 30 obtained in the line 33, the naphtha fraction and middle fraction fractionated in the rectifying tower 40 are used. , Wax fractions, or kerosene fractions obtained by hydrotreating these fractions, gas oil fractions, diesel fuels obtained by arbitrarily mixing kerosene fractions and gas oil fractions, etc. Can be used. In the present invention, the FT synthetic crude oil after magnetic separation obtained in the line 33 can be preferably used as a cleaning liquid.

  In the washing and removing process, the magnetic field around the packing is lost (the magnetic coil for the magnetic separator is turned off), and the cleaning liquid is introduced into the separator 30 from the bottom of the separator tower via the line 35 to the packing. It is simply an operation to wash off the adhering magnetic particles. The cleaning liquid is discharged out of the system from the line 36. As cleaning conditions, the cleaning liquid linear velocity is 1 to 10 cm / sec, preferably 2 to 6 cm / sec.

The magnetic separation process will be described below with reference to FIG.
FIG. 2 is a schematic simplified view of the high gradient magnetic separator 30 used in the present invention. The separation part of the high gradient magnetic separator 30 is a vertical packed tower, which is filled with a ferromagnetic packing. The packed bed 31 filled with the packing is magnetized by the magnetic field lines generated by the electromagnetic coil 32 outside the tower to form a high-gradient magnetic separation part. This portion is a uniform high magnetic field space generated by the external electromagnetic coil. The liquid heated to a suitable temperature for operation passes from the line 21 to the line 33 from below to the line 33 at a predetermined flow rate, preferably a flow rate at which the liquid residence time is 15 seconds or more. It is removed by adhering to the surface of objects.

  While the FT synthetic crude oil passes through the magnetic separator 30 from the line 21, the washing liquid bypasses through the washing oil bypass line (not shown), and the washing liquid flows into the magnetic separator 30 from the line 35. During washing, the liquid component can be bypassed through a liquid component bypass line (not shown) and sent to the rectification column 40. In this way, it is possible to perform switching between removal operation, cleaning operation, and repeated continuous operation. The washing and removing step can be performed with reference to the method described in JP-A-6-200260.

Here, the fine particles in the FT slurry after the FT synthesis reactor are fine, and the amount thereof is large, and if this state is processed in the magnetic separation step, the washing frequency of the packing is increased. . As a result, magnetic separation must be complicated.
Therefore, in the present invention, a separate liquid-solid separation step 20 other than the magnetic separation step is provided before the magnetic separation step, and thus the intermittent cleaning interval in the magnetic separation step is lengthened.

  The separate liquid-solid separation step 20 other than the magnetic separation step as the pretreatment is selected from a filter using an appropriate filter such as a sintered metal filter, a gravity sedimentation separator, a cyclone, a centrifuge, and the like. Any of the conventional methods can be used. For example, a sedimentation tank (gravity sedimentation separator / natural sedimentation method) in which the slurry is filled and the solid particles in the slurry are allowed to settle for a certain period of time can be used. A natural sedimentation type gravity sedimentation separator is advantageous because of its simple structure. These can be used either continuously or batchwise. Although FIG. 1 illustrates the case where there is one liquid-solid separation step before the magnetic separation step, a plurality of liquid-solid separation steps may be provided. The separator 20 separates and removes solid particles at line 22 and the FT synthetic crude oil is introduced from line 21 to the high gradient magnetic separator 30 described above. The operation in the high gradient magnetic separator 30 is as described above.

The FT synthetic crude oil from which the solid particles are separated and removed by the separators 20 and 30 in the lines 22 and 34, respectively, is sent to the rectification tower 40 via the line 33, where it is rectified and hydrogenated. Various purification treatments such as chemical conversion treatment are applied to produce products.
That is, the liquid fraction obtained in the magnetic separation step 30 is inserted into the rectifying column 40 from the line 33 and fractionated. For example, a naphtha fraction (boiling point less than 150 ° C.) is fed from the line 41 to the middle fraction ( A boiling point of 150 to 350 ° C. is fractionated from the line 42 and a wax fraction (boiling point of 350 ° C. or higher) is fractionated from the line 43, respectively. Although it is fractionated into 3 fractions in the figure, it may be 2 fractions or 3 fractions or more. Moreover, it can also use for the next refinement | purification process, without being especially distilled. After fractional distillation, various purification treatments such as hydrogenation treatment are performed to obtain products.
Specific hydrotreatments include hydrorefining naphtha fraction (boiling point less than 150 ° C) with hydrorefining equipment, or middle distillate (boiling point 150-350 ° C) with hydroisomerization equipment. Hydroisomerization (reactions such as isomerizing liquid hydrocarbons or adding hydrogen to unsaturated bonds to saturate them), and hydrogenating wax fractions (boiling point 350 ° C or higher) with a hydrogenolysis unit It can be decomposed.

  INDUSTRIAL APPLICABILITY The present invention can be used for a method of separating and removing magnetic particles contained in FT synthetic crude oil obtained by FT synthesis using carbon monoxide and hydrogen as raw materials by a magnetic separator.

A synthesis gas containing carbon monoxide and hydrogen gas obtained by reforming natural gas as main components is sent from a line 1 to a bubble column type hydrocarbon synthesis reactor (FT synthesis reactor) 10 and an FT catalyst. Liquid hydrocarbons were synthesized by reacting in a slurry in which particles (average particle size of 100 μm, cobalt as an active metal was supported by 30% by weight) were suspended.
The liquid hydrocarbon synthesized in the FT synthesis reactor 10 is taken out from the line 3 as a slurry containing FT catalyst particles, and a first liquid-solid separator (gravity) arranged at the rear stage of the FT synthesis reactor 10 is taken out. The catalyst particles are removed with a sedimentation separator (natural sedimentation method) 20.

Subsequently, a liquid component (liquid A) containing catalyst particles that could not be separated by the first liquid-solid separator 20 is second liquid-solid separation step (electromagnetic high gradient magnetic separator (FEROSEP (registered trademark))) 30. Then, the catalyst particles and the liquid component (liquid B) which are solid components are further separated.
Table 1 shows the residual magnetic particle concentration (mass ppm) at the inlet and outlet of the magnetic separator 30 as the second liquid-solid separation step, and the magnetic particle removal rate by magnetic separation.

  Here, the residual magnetic particle concentration (mass ppm) at the inlet and outlet of the magnetic separator is the weight of slurry or oil based on the measurement result of a laser diffraction particle size distribution analyzer SALD-3100 manufactured by Shimadzu Corporation. This value is calculated based on the standard. The larger the inlet value, the higher the FT catalyst particle concentration contained in the liquid A. When the outlet concentration is constant, the larger the inlet value, the higher the magnetic separator. This means that the load increases.

The high gradient magnetic separator 30 used in the second liquid-solid separation step has a cleaning liquid introduction line 35 for internal cleaning and a line 36 for discharging the cleaning liquid, and is a catalyst separated by intermittent cleaning. Discharge particles out of the system. Table 1 shows the cleaning interval at this time. In addition, as a washing | cleaning liquid, a part of FT synthetic crude oil (liquid B) obtained from the line 33 was used.
The liquid fraction (liquid B) obtained in the second liquid-solid separation step 30 is guided to the rectification column 40 for fractionation, and the naphtha fraction (boiling point is less than 150 ° C.) 41 and middle fraction (boiling point is 150 ° C.). To 350 ° C.) and a wax fraction (boiling point: 350 ° C. or higher) 43.

(Example 2)
The sedimentation time of the gravity sedimentation separator 20 which is the first liquid-solid separation step is adjusted so that the residual particle concentration (mass ppm) at the inlet of the magnetic separator becomes the concentration described in Table 1, and the second The same processing as in Example 1 was performed except that the processing conditions (see Table 1) of the high gradient magnetic separator, which is the liquid-solid separation step, were changed.

(Comparative Example 1)
The same processing as in Example 1 was performed except that the first liquid-solid separation step was not provided and the processing conditions (see Table 1) of the high gradient magnetic separator that was the second liquid-solid separation step were changed. . In this case, since the residual magnetic particle concentration at the inlet of the high gradient magnetic separator is high, the magnetic particle concentration at the outlet cannot be reduced to 10 ppm by mass, and the high gradient magnetic separator cannot be operated.

(Comparative Example 2)
The first liquid-solid separation step is not provided, the processing conditions (see Table 1) of the high-gradient magnetic separator that is the second liquid-solid separation step are changed, and the residual particle concentration (mass by mass) at the inlet of the magnetic separator (ppm) was the same as that of Example 1 except that the FT synthesis reaction was performed under the condition of 1000 ppm by mass.

(result)
In any of the examples, the washing interval can be increased by lowering the load of the high gradient magnetic separator, and the magnetic particles (FT catalyst particles) can be efficiently removed from the slurry as compared with the comparative example.

A fuel production plant comprising an FT synthesis reactor 10, a liquid-solid separator 20 for separating magnetic particles in FT synthetic crude oil, and a high gradient magnetic separator 30 for magnetic separation. It is a model schematic diagram of the high gradient magnetic separator 30 used for this invention.

Explanation of symbols

10 FT synthesis reactor 20 liquid-solid separator 30 high gradient magnetic separator 40 rectifying tower for fractionating FT synthetic crude oil

Claims (2)

In a method for producing a synthetic oil, a crude Fischer-Tropsch synthetic crude oil obtained by a Fischer-Tropsch synthesis method is processed in a purification step including distillation.
A magnetic separation step for capturing and removing magnetic particles by a high-gradient magnetic separator having a cleaning liquid introduction line for intermittently cleaning the captured magnetic particles and a line for discharging the cleaned cleaning liquid before the purification step. And a separate liquid-solid separation step as a pretreatment of the magnetic separation step.   The liquid-solid separation step as the pretreatment according to claim 1 is a liquid-solid separation step using any one selected from a filter, a gravity sedimentation separator, a cyclone, and a centrifuge. Manufacturing method.

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