JP2020164683A - Method of cleaning crude oil heat exchanger of fluid catalytic cracking apparatus - Google Patents

Abstract

To provide a cleaning method capable of reducing dirt adhesion, during operation, to a crude oil heat exchanger of a fluid catalytic cracking apparatus and sufficiently and simply curbing the dirt adhesion to the crude oil heat exchanger of the fluid catalytic cracking apparatus.SOLUTION: A method of cleaning a crude oil heat exchanger of a fluid catalytic cracking apparatus of this invention causes a stock oil for cleaning to circulate the crude oil heat exchanger of the fluid catalytic crack apparatus, the stock oil for cleaning: containing at least one type of hydrocarbon oil selected from desulfurized vacuum gas oil and direct desulfurized heavy oil; having density of 0.85-1.0 kg/cm3 at 15°C; containing 90-99 vol.% of stock oil for fluid catalytic cracking apparatus that contains 1.0 mass% or less of asphaltene; containing at least one type of hydrocarbon oil selected from an extract obtained from a furfural extracting step when producing catalytic cracking gas oil and lubricant and a toluene fraction obtained from an apparatus for distillation separation of mixed xylene; and containing 1-10 vol.% of fuel oil base that contains 40-80 vol.% of aromatic group.SELECTED DRAWING: None

Description

The present invention relates to a method of cleaning a raw material oil heat exchanger of a fluid catalytic cracking (FCC).

A fluid catalytic cracking device (FCC) is a device that cracks heavy oil fractions with a large molecular weight into low molecular weight gasoline fractions and intermediate fractions in a petroleum refining process, and cracks into heavy oil at a high temperature of 500 ° C or higher. It is an apparatus for cracking a heavy oil fraction by contacting it with a fluidized catalytic cracking catalyst (see, for example, Patent Document 1 (Japanese Unexamined Patent Publication No. 11-10204)).
According to the fluid catalytic cracking device, it is possible to produce gasoline fractions from heavy oil, which is difficult to use as it is due to environmental load, etc., so it is a very important device in the petroleum refining field and at the same time, a limited resource. It is an environment-friendly processing device that can make effective use of.

As the raw material oil to be processed by the fluidized catalytic cracking apparatus, desulfurized heavy oil, thermal cracking desulfurized heavy oil, indirect desulfurized heavy oil, direct desulfurized heavy oil and the like are used, and these raw material oils are heat exchangers (in some cases, heat exchangers). After being preheated to around 300 ° C. in a heating furnace), it is put into a fluidized cracking apparatus.

JP-A-11-10204 No.

However, as examined by the present inventor, as described above, since the raw material oil to be treated in the fluid catalytic cracking apparatus is composed of heavy oil, it is deposited on the heat exchange site when preheated using a heat exchanger. It has been found that an object (dirt) adheres and the heat exchange efficiency tends to decrease. When the heat exchange efficiency is lowered, the raw material oil charged into the fluidized catalytic cracker is not sufficiently heated, and therefore a larger amount of energy is required for processing with the hydraulic cracker, so that the temperature rises sharply. It tends to shorten the life of catalysts and reactors and increase production costs.

Under such circumstances, the present invention can sufficiently reduce the adhesion of dirt to the raw material oil heat exchanger of the fluidized catalytic cracking apparatus during operation, and can sufficiently reduce the adhesion of dirt to the raw material oil heat exchanger of the fluidized catalytic cracking apparatus. It is an object of the present invention to provide a cleaning method that can be easily suppressed.

As a result of diligent studies by the present inventors in order to solve the above technical problems, the composition may contain a certain amount of raw material oil base material which is soluble in the causative component of the dirt adhering to the preheating heat exchanger. For example, the idea was to suppress the adhesion of dirt to the wall surface of the heat exchanger, or to dissolve the dirt once it had adhered.

As a result of further studies by the present inventors based on the above findings, at least one or more hydrocarbon oils selected from desulfurization reduced pressure gas oil and direct desulfurization heavy oil, which are methods for cleaning the raw material oil heat exchanger of the fluidized catalytic cracking apparatus. Contains 90 to 99% by volume of raw material oil for a fluid cracking apparatus having a density of 0.85 to 1.0 kg / cm ^{3 at} 15 ° C. and an asphaltene content of 1.0% by mass or less, and catalytic cracking. It contains at least one hydrocarbon oil selected from the toluene distillates obtained from the extract obtained by the cracking process in the production of light oil and lubricating oil and the apparatus for distilling and separating mixed xylene, and has an aromatic content of 40. We have found that the above object can be achieved by a method of distributing a raw material oil for cleaning containing 1 to 10% by volume of a fuel oil base material of about 80% by volume to a raw material oil heat exchanger of a fluid cracking apparatus. The present invention has been completed based on this finding.

That is, the present invention
(1) A method for cleaning a raw material oil heat exchanger of a fluidized catalytic cracker.
Desulfurization A flow containing at least one hydrocarbon oil selected from vacuum gas oil and direct desulfurization heavy oil, having a density of 0.85 to 1.0 kg / cm ^{3 at} 15 ° C. and an asphaltene content of 1.0% by mass or less. Contains 90-99% by volume of raw material oil for catalytic crackers and
Contains at least one hydrocarbon oil selected from the toluene distillate obtained from the equipment that distills and separates the extract and mixed xylene obtained by the furfural extraction step in the production of catalytically cracked gas oil and lubricating oil, and has an aromatic content. A raw material oil for cracking containing 1 to 10% by volume of a fuel oil base material having a content of 40 to 80% by volume.
A method for cleaning a raw material oil heat exchanger of a fluidized catalytic cracker, which is characterized in that it is distributed to the raw material oil heat exchanger of the fluidized catalytic cracker.
(2) The above (1), wherein only the oil to be treated for the fluid catalytic cracking apparatus is circulated to the raw material oil heat exchanger of the fluid catalytic cracking apparatus, and then the process of distributing the raw material oil for cleaning is repeated. Cleaning method,
(3) The cleaning method is the following formula (I).
{(V2 × C) / V1} ≧ 0.20 (I)
(However, V1 is the distribution amount (L) of the oil to be processed for the fluidized contact decomposition device that was distributed before the cleaning raw material oil was distributed, and V2 is the cleaning raw material oil when the cleaning raw material oil was distributed. The distribution amount (L) and C of the fuel base material contained therein are the content ratio (volume%) of the fuel base material in the cleaning raw material oil.)
The cleaning method according to (1) or (2) above, which comprises distributing the raw material oil for cleaning so as to satisfy the above conditions.

According to the present invention, the adhesion of dirt to the raw material oil heat exchanger of the fluidized catalytic cracking apparatus can be reduced during operation, and the adhesion of dirt to the raw material oil heat exchanger of the fluidized catalytic cracking apparatus can be sufficiently and easily performed. A cleaning method that can be suppressed can be provided.

It is a conceptual diagram of the dirt evaluation apparatus of the heat exchanger used in the Example and the comparative example of this invention.

The method for cleaning the raw material oil heat exchanger of the fluidized catalytic cracking apparatus according to the present invention is a method for cleaning the raw material oil heat exchanger of the fluidized catalytic cracking apparatus.
Desulfurization A flow containing at least one hydrocarbon oil selected from vacuum gas oil and direct desulfurization heavy oil, having a density of 0.85 to 1.0 kg / cm ^{3 at} 15 ° C. and an asphaltene content of 1.0% by mass or less. Contains 90-99% by volume of raw material oil for catalytic crackers and
Contains at least one hydrocarbon oil selected from the toluene distillate obtained from the equipment that distills and separates the extract and mixed xylene obtained by the furfural extraction step in the production of catalytically cracked gas oil and lubricating oil, and has an aromatic content. A raw material oil for cracking containing 1 to 10% by volume of a fuel oil base material having a content of 40 to 80% by volume.
It is characterized in that it is distributed to a raw material oil heat exchanger of a fluidized catalytic cracker.

The raw material oil for cleaning used in the present invention contains at least one hydrocarbon oil selected from desulfurized vacuum light oil and direct desulfurized heavy oil, has a density of 0.85 to 1.0 kg / cm ^{3 at} 15 ° C., and contains asphaltene. It contains 90 to 99% by volume of raw material oil for a fluidized catalytic cracking apparatus having an amount of 1.0% by mass or less.

In the present invention, the density of the raw material oil for a fluid catalytic cracker at 15 ° C. is 0.85 to 1.0 kg / cm ³ , preferably 0.85 to 0.95 kg / cm ³ , and 0.86. more preferably ~0.95kg / cm ^3, further preferably 0.86~0.94kg / cm ^3.

Since the density of the raw material oil for a fluid catalytic cracker at 15 ° C. is within the above range, a sufficient calorific value per volume can be easily exhibited, and when used in an industrial furnace or a boiler, combustion is non-uniform. Sex and misfire can be easily suppressed.
In this application document, the density at 15 ° C. means the value measured by JIS K2247-1: 2011.

In the present invention, the boiling point range of the feedstock oil for a fluid catalytic cracker is preferably 170 to 750 ° C., more preferably 175 to 750 ° C., and even more preferably 175 to 745 ° C.
In this application document, the boiling point range means a value measured by JIS K2254: 1998.

In the present invention, the aromatic content of the feedstock oil for a fluid catalytic cracker is preferably 5 to 30% by mass, more preferably 8 to 30% by mass, and preferably 10 to 30% by mass. More preferred.
In addition, in this application document, the aromatic content means the value measured by JPI-5S-49-97.

In the present invention, the asphaltene content of the feedstock oil for a fluid catalytic cracker is 1.0% by mass or less, preferably 0.9% by mass or less, and more preferably 0.8% by mass or less.
When the asphaltene content of the raw material oil for the fluid catalytic cracker is within the above range, the dirt adhering to the raw material oil heat exchanger can be easily reduced or suppressed, and it is used in an industrial furnace, a boiler, etc. At that time, the amount of sludge accumulated can be easily suppressed.
In this application document, the asphaltene content means a value measured according to JPI-5S-22-83.

In the present invention, the 90% by volume distillation temperature of the feedstock oil for a fluid catalytic cracker is preferably 450 to 650 ° C, more preferably 450 to 640 ° C, and further preferably 450 to 630 ° C. preferable.
When the 90% by volume distillation temperature of the raw material oil for the fluid catalytic cracker is within the above range, the content of the heavy wax distillate, which is considered to be the cause of stains on the heat exchanger, is suppressed, and the stains are effectively removed. It can be reduced.
In addition, in this application document, 90% by volume distillation temperature means the value measured by JIS K2254: 1998.

In the present invention, the density at 15 ℃ desulfurization vacuum gas oil, is preferably 0.85~0.92kg / cm ^3, more preferably 0.86~0.92kg / cm ^3, 0.86 It is more preferably ~ 0.91 kg / cm ³ .
When the density of desulfurized vacuum gas oil is within the above range, a sufficient calorific value per volume can be easily exhibited, and when used in an industrial furnace or a boiler, combustion non-uniformity or misfire can be caused. It can be easily suppressed.

In the present invention, the aromatic content of the desulfurized reduced pressure gas oil is preferably 5 to 18% by mass, more preferably 8 to 18% by mass, and further preferably 10 to 18% by mass.

In the present invention, the amount of asphaltene in the desulfurized reduced pressure gas oil is preferably 2.0% by mass or less, more preferably 1.9% by mass or less, and further preferably 1.8% by mass or less.
When the amount of asphaltene in the desulfurized reduced pressure gas oil is within the above range, dirt adhering to the raw material oil heat exchanger can be reduced or suppressed. In addition, the amount of sludge accumulated can be suppressed when used in an industrial furnace or a boiler.

In the present invention, the 90% by volume distillation temperature of the desulfurized reduced pressure gas oil is preferably 450 to 650 ° C, more preferably 450 to 640 ° C, and even more preferably 450 to 630 ° C.
When the 90% by volume distilling temperature of the desulfurized reduced pressure gas oil is within the above range, the content of heavy wax distillate, which is considered to be the cause of stains on the heat exchanger, can be suppressed, and the stains can be effectively reduced. it can.

In the present invention, the density at 15 ℃ direct desulfurized gas oil is preferably 0.85~0.92kg / cm ^3, more preferably 0.86~0.92kg / cm ^3, 0.86 It is more preferably ~ 0.91 kg / cm ³ .
When the density of desulfurized vacuum gas oil is within the above range, it is possible to easily exert a sufficient calorific value per volume, and when used in an industrial furnace or boiler, combustion non-uniformity or misfire can be caused. It can be suppressed.

In the present invention, the aromatic content of the direct desulfurized gas oil is preferably 10 to 30% by mass, more preferably 15 to 30% by mass, and even more preferably 18 to 30% by mass.

In the present invention, the amount of asphaltene in the direct desulfurized gas oil is preferably 2.0% by mass or less, more preferably 1.9% by mass or less, and further preferably 1.8% by mass or less.
When the amount of asphaltene in the direct desulfurized gas oil is within the above range, it is possible to reduce or suppress the dirt adhering to the raw material oil heat exchanger. In addition, the amount of sludge accumulated can be easily suppressed when used in an industrial furnace, a boiler, or the like.

In the present invention, the 90% by volume distillation temperature of the direct desulfurized gas oil is preferably 450 to 650 ° C, more preferably 450 to 640 ° C, and even more preferably 450 to 630 ° C.
When the 90% by volume distillation temperature of the direct desulfurized gas oil is within the above range, the content of the heavy wax distillate, which is considered to be the cause of stains on the heat exchanger, can be suppressed, and the stains can be effectively reduced. it can.

The raw material oil for cleaning used in the present invention is at least one selected from a toluene distillate obtained from an apparatus for distilling and separating an extract and a mixed xylene obtained by a furfural extraction step in producing catalytically cracked gas oil and lubricating oil. Contains 1 to 10% by volume of a fuel oil base material containing 40 to 80% by volume of aromatic content.

In the present invention, the aromatic content of the fuel oil base material is 40 to 80% by mass, preferably 42 to 80% by mass, and more preferably 45 to 80% by mass.
When the aromatic content of the fuel oil base material is within the above range, the raw material oil for cleaning exhibits excellent dissolving power, and the dirt on the heat exchanger can be reduced more effectively.

In the present invention, the 90% by volume distillation temperature of the fuel oil base material is preferably 70 to 600 ° C., more preferably 72 to 600 ° C., and even more preferably 75 to 600 ° C.
When the 90% by volume distillate temperature of the fuel oil base material is within the above range, the content of heavy wax distillate, which is considered to be the cause of stains on the heat exchanger, is suppressed, and the stains are effectively reduced. Can be done.

In the present invention, the asphaltene content of the fuel oil base material is preferably 1.0% by mass or less, more preferably 0.8% by mass or less, and further preferably 0.5% by mass or less. preferable.
When the asphaltene content of the fuel oil base material is within the above range, dirt adhering to the raw material oil heat exchanger can be easily reduced or suppressed. In addition, the amount of sludge accumulated can be easily suppressed when used in an industrial furnace, a boiler, or the like.

In the present invention, the fuel oil base material is a distillate of at least one selected from toluene obtained from an apparatus for distilling and separating an extract or mixed xylene obtained by a furfural extraction step in producing catalytically cracked gas oil and lubricating oil. Including minutes.
Since the fuel oil base material contains the above distillate, the raw material oil heat without stopping the continuous operation of the fluidized catalytic cracking apparatus without significantly reducing the amount of raw material oil processed while suppressing the influence on the fluidized catalytic cracking reaction. Dirt adhering to the exchanger can be reduced.

In the present invention, the catalytic cracking gas oil means a catalytic cracking gas oil, that is, a light cycle oil, which is obtained as an intermediate fraction when a heavy oil is subjected to a catalytic cracking treatment.

In the present invention, the aromatic content of the catalytically cracked gas oil is preferably 40 to 80% by volume, more preferably 42 to 80% by volume, and even more preferably 45 to 80% by volume.
When the aromatic content of the catalytic cracking gas oil is within the above range, the dissolving power of the mixed raw material oil for the fluid cracking apparatus is improved, and the dirt adhering to the raw material oil heat exchanger is effectively reduced. Can be done.

In the present invention, the 90% by volume distillation temperature of the catalytically cracked gas oil is preferably 280 to 390 ° C, more preferably 290 to 390 ° C, and even more preferably 300 to 390 ° C.
When the 90% by volume distillate temperature of the catalytic cracking gas oil is within the above range, (when mixed with the raw material oil, the content of heavy wax is easily suppressed, and stains can be effectively reduced.

In the present invention, the asphaltene content of the catalytically cracked gas oil is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, and further preferably 0.01% by mass or less. ..
When the asphaltene content of the catalytically cracked gas oil is within the above range, dirt adhering to the raw material oil heat exchanger can be easily reduced or suppressed. In addition, the amount of sludge accumulated can be easily suppressed when used in an industrial furnace, a boiler, or the like.

In the present invention, the extract is a medium or heavy vacuum distillation distillate obtained by vacuum distillation of a crude oil at atmospheric pressure or a deflated oil (bright stock oil) of a vacuum distillation residue oil. It means oil extracted and separated by.
Since the residue extracted with furfural or the like is used as a lubricating oil base oil called raffinate, the extract is industrially obtained in the lubricating oil manufacturing process.

In the present invention, the aromatic content of the extract is preferably 40 to 70% by mass, more preferably 45 to 70% by mass, and even more preferably 50 to 70% by mass.
When the aromatic content of the extract is within the above range, the dissolving power of the mixed raw material oil for the fluid catalytic cracker is improved, and the dirt adhering to the raw material oil heat exchanger can be effectively reduced. it can.

In the present invention, the 90% by volume distillation temperature of the extract is preferably 500 to 600 ° C., more preferably 510 to 600 ° C., and even more preferably 520 to 600 ° C.
When the 90% by volume distillate temperature of the extract is within the above range, the content of heavy wax is easily suppressed when mixed with the raw material oil, and stains can be effectively reduced.

In the present invention, the asphaltene content of the extract is preferably 1.0% by mass or less, more preferably 0.8% by mass or less, and further preferably 0.5% by mass or less.
When the asphaltene content of the extract is within the above range, dirt adhering to the raw material oil heat exchanger can be reduced or suppressed. In addition, the amount of sludge accumulated can be suppressed when used in an industrial furnace or a boiler.

In the present invention, the toluene fraction means a toluene-based fraction obtained from an apparatus that distills and separates mixed xylene, and has a boiling point range of 70 to 130 ° C., preferably 72 to 130 ° C. Some are more preferred, and those at 75-130 ° C are even more preferred.
The device for distilling and separating mixed xylene is a device for distilling heavy-modified naphtha to obtain mixed xylene containing o-xylene and p-xylene as main components, and distilling and separating toluene as a by-product. be able to.

In the present invention, the aromatic content of the toluene fraction is preferably 60 to 80% by mass, more preferably 62 to 80% by mass, and even more preferably 65 to 80% by mass.
When the aromatic content of the toluene fraction is within the above range, the dissolving power of the mixed raw material oil for the fluid catalytic cracker is easily improved, and the dirt adhering to the raw material oil heat exchanger is effectively reduced. can do.

In the present invention, the content ratio of the raw material oil for fluid catalytic cracking constituting the raw material oil for cleaning is 90 to 99% by volume, preferably 90 to 98.5% by volume, and 90 to 98% by volume. Is more preferable.
Further, in the present invention, the content ratio of the fuel oil base material constituting the raw material oil for cleaning is 1 to 10% by volume, preferably 1.5 to 10% by volume, and 2 to 10% by volume. Is more preferable.
Since the oil content of the fuel oil base material constituting the raw material oil for cleaning is within the above range, it is possible to reduce the dirt adhering to the raw material oil heat exchanger without stopping the continuous operation of the fluidized catalytic cracking apparatus. It is possible to extend the period until the continuous operation of the fluid catalytic cracking apparatus is stopped and the heat exchanger is released and cleaned. In addition, it is possible to economically process the raw material oil without significantly reducing the amount of the raw material oil processed, while further reducing the amount of the high value-added fuel oil base material used for cleaning.

In the cleaning method according to the present invention, after only the oil to be treated for the fluid catalytic cracking apparatus is circulated to the raw material oil heat exchanger of the fluid catalytic cracking apparatus, the process of distributing the raw material oil for cleaning is repeated. Is preferable.
Examples of the oil to be treated for the fluid catalytic cracking apparatus include the same oils as the raw material oil for the fluid catalytic cracking apparatus described above.
The raw material oil for cleaning after the distribution of the oil to be treated for the fluid catalytic cracking apparatus may be distributed regularly or irregularly, but it is preferable to perform it regularly.
By alternately distributing the oil to be treated for the fluidized catalytic cracking apparatus and the raw material oil for cleaning in this way, the oil heat exchanger is sufficiently adhered to the raw oil heat exchanger without stopping the continuous operation of the fluidized catalytic cracking apparatus. Moreover, it can be easily reduced.

In the cleaning method according to the present invention, the following formula (I)
{(V2 × C) / V1} ≧ 0.20 (I)
(However, V1 is the distribution amount (L) of the oil to be processed for the fluidized contact decomposition device that was distributed before the cleaning raw material oil was distributed, and V2 is the cleaning raw material oil when the cleaning raw material oil was distributed. The distribution amount (L) and C of the fuel base material contained therein are the content ratio (volume%) of the fuel base material in the cleaning raw material oil.)
It is preferable to distribute the raw material oil for cleaning so as to satisfy the above conditions.

In the formula (I), when the oil to be treated for the fluid catalytic cracker and the raw material oil for cleaning are distributed once each, V1 and V2 are the respective distribution amounts (L).
In the formula (I), when the process of circulating the raw material oil for cleaning is repeated after distributing only the oil to be processed for the fluidized contact decomposition device, only the oil to be processed for the fluidized contact decomposition device is distributed and immediately after that. The distribution amount of the raw material oil for cleaning is one process, the flow amount of the oil to be processed for the fluidized contact decomposition device at each process is V1 (L), and the flow amount of the raw material oil for cleaning is V2 (L). Calculate the ratio.

The value represented by the above formula {(V2 × C) / V1} is 0.20 or more, preferably 0.22 or more, and more preferably 0.25 or more.

By circulating the raw material oil for cleaning periodically or irregularly so as to satisfy the formula (I) in the cleaning method according to the present invention, it adheres to the raw material oil heat exchanger without stopping the continuous operation of the fluidized catalytic cracking apparatus. It is possible to reduce the amount of dirt generated, and it is possible to extend the period until the continuous operation of the fluidized contact cracking apparatus is stopped and the heat exchanger is released and cleaned. Further, it is possible to reduce the amount of the high value-added fuel oil base material used for cleaning without significantly reducing the amount of the raw material oil to be processed, and the economical processing becomes possible.

According to the present invention, the adhesion of dirt to the raw material oil heat exchanger of the fluidized catalytic cracking apparatus can be reduced during operation, and the adhesion of dirt to the raw material oil heat exchanger of the fluidized catalytic cracking apparatus can be sufficiently and easily performed. A cracking method that can be suppressed can be provided.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to these examples.

(Example 1)
(1) Adjustment of base material Base material A (desulfurization vacuum light oil (VGO)) and base material B (direct desulfurization heavy oil (DDSP)) having the physical properties shown in Table 1 as the base material constituting the raw material oil for the fluid cracking apparatus. )), And as the fuel oil base material C, catalytically cracked gas oil (LCO) having the physical properties shown in Table 1 was prepared.
Further, the raw material oil in which the base material A is mixed at a ratio of 70% by volume and the base material B is mixed at a ratio of 30% by volume, the base material A is 63% by volume, the base material B is 27% by volume, and the base material C is 10% by volume. A raw material oil for cleaning mixed in proportion was prepared.
The physical properties of each base material and raw material oil are shown below.

(2) Cleaning Method As shown in a schematic cross-sectional view in FIG. 1, 1.2 L of the above raw material oil stored in the raw material oil tank T1 and heated to 70 ° C. by the hot plate HP is also (not shown) a ribbon heater. Heater rods R (made of stainless steel, length) were sent into the flow pipe c (straight 6.5 mm) at 10 mL / min while the entire flow path was maintained at 70 ° C. After continuing the operation of sequentially heating the heating heater HT1 and the heating heater HT2 (200 mm, diameter 6 mm) at the set temperatures T1 (170 ° C.) and T2 (300 ° C.) and returning them to the raw material oil tank T1 for 370 minutes. , Valve V1 was switched, and the raw material oil for cleaning stored in the cleaning tank T2 was passed through the oil at 10 mL / min for 10 minutes. At this time, the valve V2 was opened to prevent the raw material oil for cleaning from being mixed into the raw material tank. After 10 minutes, the valve V1 was returned to the raw material tank side, the cleaning oil in the flow path was completely discharged, the valve V2 was closed, the raw material oil was restarted, and continued for 260 minutes. Table 2 shows the results when the heater outlet temperature T3 of the raw material oil was measured by the raw material oil temperature measuring means Tm2out arranged at the raw material oil outlet of the heater HT2.

(Example 2)
After the raw material oil was continued for 500 minutes from the start of operation, the heater outlet temperature T3 was measured under the same conditions as in Example 1 except that the raw material oil for cleaning was passed through the oil at 10 mL / min for 10 minutes. The results are shown in Table 2.

(Example 3)
After the raw material oil was continued for 300 minutes from the start of operation, the raw material oil for cleaning was passed through at 10 mL / min for 10 minutes, and then the raw material oil was passed through for 60 minutes. Then, the cleaning oil raw material oil was passed through at 10 mL / min for 10 minutes, and the raw material oil was passed through for 60 minutes. After that, the raw material oil for cleaning was passed through at 10 mL / min for 10 minutes, and the raw material oil was passed through for 60 minutes. After that, the raw material oil for cleaning was passed through at 10 mL / min for 10 minutes, and the heater outlet temperature T3 was measured under the same conditions as in Example 1 except that the raw material oil was passed through for 120 minutes. The results are shown in Table 2.

(Comparative Example 1)
The heater outlet temperature T3 was measured under the same conditions as in Example 1 except that the raw material oil for cleaning was not passed through. The results are shown in Table 2.

Table 3 shows the calculation results of the formula {(V2 × C) / V1} in each Example and Comparative Example.

From Table 2, Example 1 is between 370 and 380 minutes after the start of measurement, Example 2 is between 500 and 510 minutes after the start of measurement, and Example 3 is 300 to 310 minutes and 370 to 380 minutes after the start of measurement. It can be seen that the heater outlet temperature T3 has changed from a downward trend to an upward trend before and after the passage of the cleaning raw material oil between 440 to 450 minutes and 510 to 520 minutes.

On the other hand, from Table 2, it can be seen that in Comparative Example 1, since the raw material oil for cleaning was not mixed, the heater outlet temperature tended to decrease almost during the measurement period, and decreased by about 50 ° C. from the start of measurement. In Examples 1 to 3 in which the raw material oil for cleaning was mixed, the heater outlet temperature was higher than that in Comparative Example 1 at the end of the measurement, so that the dirt adhering to the heater rod R due to the oil flow of the raw material oil was washed. It shows that it has been reduced. Further, by repeatedly passing the raw material oil for cleaning as in Example 3, dirt adhesion due to the heat exchanger is reduced, and the period of continuous operation of the fluidized catalytic cracking apparatus and the raw material oil heat exchanger can be extended. I understand.

Further, from Tables 2 and 3, in Examples 1 to 3 in which the cleaning raw material oil was distributed so as to satisfy the formula {(V2 × C) / V1} ≧ 2.0, the heater outlet temperature was the cleaning raw material oil. Since it rises immediately after distribution, it can be seen that the dirt adhering to the cleaning raw material oil before distribution can be effectively reduced. Further, the value calculated by the formula {(V2 × C) / V1} of Example 2 to which the dirt is most adhered is 0.20, the desired effect is obtained, and the raw material oil causing the dirt. Since the desired effect was obtained in Examples 1 and 3 in which the amount of the oil distributed was smaller and the value calculated by the formula {(V2 × C) / V1} was larger than that in Example 2, the raw material oil for cleaning was obtained. It can be seen that the desired effect can be obtained if the value calculated by the formula {(V2 × C) / V1}, which is the ratio of the distribution amount of the feedstock to the feedstock oil, is 0.2 or more.
On the other hand, in Comparative Example 1, since the cleaning oil raw material oil was not added, the distribution amount of the raw material oil was increased and the adhered dirt was not reduced, and as a result, the heater outlet temperature was lowered. Recognize.

According to the present invention, the adhesion of dirt to the raw material oil heat exchanger of the fluidized catalytic cracking apparatus can be reduced during operation, and the adhesion of dirt to the raw material oil heat exchanger of the fluidized catalytic cracking apparatus can be sufficiently and easily performed. A cleaning method that can be suppressed can be provided.

T1, T2: Tank V1, V2: Switching valve HP: Hot plate c: Distribution pipe HT1, HT2: Heater R: Heater rod P: Pump

Claims (3)

This is a cleaning method for the raw material oil heat exchanger of a fluid catalytic cracker.
Desulfurization A flow containing at least one hydrocarbon oil selected from vacuum gas oil and direct desulfurization heavy oil, having a density of 0.85 to 1.0 kg / cm ^{3 at} 15 ° C. and an asphaltene content of 1.0% by mass or less. Contains 90-99% by volume of raw material oil for catalytic crackers and
Contains at least one hydrocarbon oil selected from the toluene distillate obtained from the equipment that distills and separates the extract and mixed xylene obtained by the furfural extraction step in the production of catalytically cracked gas oil and lubricating oil, and has an aromatic content. A raw material oil for cracking containing 1 to 10% by volume of a fuel oil base material having a content of 40 to 80% by volume.
A method for cleaning a raw material oil heat exchanger of a fluidized contact cracking apparatus, which comprises distributing to the raw material oil heat exchanger of the fluidized catalytic cracking apparatus. The cleaning method according to claim 1, wherein the process of distributing only the oil to be treated for the fluid catalytic cracking apparatus to the raw material oil heat exchanger of the fluid catalytic cracking apparatus and then circulating the raw material oil for cleaning is repeated. The cleaning method is the following formula (I)
{(V2 × C) / V1} ≧ 0.20 (I)
(However, V1 is the distribution amount (L) of the oil to be processed for the fluidized contact decomposition device that was distributed before the cleaning raw material oil was distributed, and V2 is the cleaning raw material oil when the cleaning raw material oil was distributed. The distribution amount (L) and C of the fuel base material contained therein are the content ratio (volume%) of the fuel base material in the cleaning raw material oil.)
The cleaning method according to claim 1 or 2, wherein the raw material oil for cleaning is distributed so as to satisfy the above conditions.