JP6796510B2 - Continuous operation method of fluid cracking machine - Google Patents

Description

The present invention relates to a method for stably and continuously operating a fluid cracking apparatus (FCC apparatus) for catalytic cracking of raw material oil for a long period of time.

Fluid catalytic cracking (FCC) is a reaction that decomposes heavy oil fractions with large molecules into low molecular weight gasoline or intermediate fractions, and contacts heavy oil with fluid catalytic cracking catalysts at a high temperature of 500 ° C. or higher. Proceed by letting. Liquid catalytic cracking can produce clean gasoline from inferior heavy oils that are difficult to use as is, which is a very important reaction in the petroleum refining field and at the same time makes effective use of limited resources. , Environmentally friendly refining process.

As an apparatus (FCC apparatus) used for such fluid catalytic cracking, an apparatus provided with a reaction column and a regeneration column has been conventionally known (see, for example, Patent Document 1). In the FCC device, the raw material oil is brought into contact with the catalyst to decompose the raw material oil, the decomposition product and the catalyst are separated in the reaction tower, the separated catalyst is transferred to the regeneration tower, and the coke on the catalyst is transferred in the regeneration tower. Is burned to regenerate the catalyst, and the regenerated catalyst is used again for the decomposition of the raw material oil.

As a catalyst used in the FCC apparatus, many catalysts have been proposed, and those composed of clay minerals, crystalline aluminosilicates, alumina binders and the like are used (see, for example, Patent Document 2).

Since the catalyst is regenerated at a temperature of about 650 to 800 ° C. in the regeneration tower, the exhaust gas discharged from the regeneration tower is 700 ° C. or higher. For this reason, the amount of heat of the exhaust gas has been recovered through a waste heat boiler.

Japanese Unexamined Patent Publication No. 11-10204 Japanese Unexamined Patent Publication No. 2008-173583

The exhaust gas from the regeneration tower is sent to the waste heat boiler via a cyclone. Heat exchange is performed in the waste heat boiler, for example, the exhaust gas is circulated in the inner pipe provided with a plurality of heat exchange tubes arranged in the cylindrical shell, and the exhaust gas is passed through the shell through a cooling medium such as in industrial water. The amount of heat is recovered and the exhaust gas is cooled to about 200 ° C.

However, it has been found that when the FCC apparatus is continuously operated for a long period of time, the heat recovery in the waste heat boiler becomes insufficient and the temperature exceeds the design temperature in the waste heat boiler. Then, it was found that the catalyst carried from the regeneration tower was deposited in the exhaust gas flow path of the waste heat boiler inner pipe and became scale, hindering the heat exchange in the waste heat boiler, and the heat recovery was insufficient. In addition, since the waste heat boiler cannot be cleaned online, the device had to be stopped when the heat transfer efficiency of the waste heat boiler deteriorated.

In addition, the heat that could not be recovered by such a waste heat boiler exceeds the design temperature of the electrostatic precipitator and flue gas treatment equipment that removes solids such as catalysts contained in the exhaust gas, so the equipment is stopped. It causes to cause. Further, the unrecovered heat becomes a load on the flue gas desulfurization apparatus, which causes a problem that the treatment efficiency of the exhaust gas is lowered. Therefore, it was necessary to periodically stop the FCC device and clean the exhaust gas flow path in the waste heat boiler while monitoring the exhaust gas temperature at the outlet of the waste heat boiler. However, since heat transfer members such as protrusions are provided in the exhaust gas flow path of the waste heat boiler inner pipe for the purpose of improving thermal conductivity, the cleaning work involves removing the protrusions, which takes time. It takes time and effort, and during that time, it is necessary to stop the FCC apparatus on a monthly basis at the longest, so that there is a problem that the processing efficiency of the raw material oil deteriorates.

Therefore, as a result of diligent studies to solve the above problems, the present inventors can solve all of the above problems by extracting a part of the used catalyst of the FCC apparatus and putting it into the exhaust gas flow path in the waste heat boiler. The present invention has been completed.
[1] A reaction tower that produces a decomposition product by bringing the raw material oil into contact with the catalyst and decomposing the raw material oil, a regeneration tower that regenerates the catalyst by burning the separated cork on the catalyst, and Equipped with exhaust gas recovery means discharged from the regeneration tower
In a fluidized catalytic cracking apparatus for raw material oil, the obtained regeneration catalyst is circulated in a reaction tower and continuously operated.
A waste heat boiler is included as an exhaust gas recovery means, and the amount of heat of the exhaust gas discharged from the regeneration tower is recovered, and a part of the used catalyst sent from the reaction tower to the regeneration tower is extracted into the exhaust gas flow path in the waste heat boiler. , A method for continuously operating a fluidized catalytic cracking apparatus, which comprises charging a part of a used catalyst.
[2] The method for continuously operating a fluid cracking apparatus according to [1], wherein the used catalyst to be charged has an average particle diameter of 40 μm or more.
[3] The used catalyst is charged at least once a week so that the amount of catalyst charged is 0.5 to 2.0 vol-ppm with respect to the exhaust gas flow rate of the waste heat boiler. The continuous operation method of the flow contact cracking apparatus according to [1].

According to the present invention, it is possible to clean the exhaust gas flow path of a waste heat boiler online without incurring a large cost. As a result, the raw material oil can be stably processed for a long period of time without stopping the FCC device, and the recovered heat can be reused, so that the FCC device can be operated in an energy-saving manner (utilization of waste heat).

It is a schematic block diagram which shows the FCC apparatus of one Embodiment of this invention. The change of the U value (total heat transfer coefficient) of the waste heat boiler with respect to the operation period in an Example and a comparative example is shown.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these.
[FCC device]
The FCC apparatus according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram showing an FCC apparatus according to an embodiment of the present invention. The FCC device 1 includes a reaction tower 11, a regeneration tower 12, and a waste heat boiler 13, and if necessary, includes a steam tank, an electrostatic precipitator, an FCC flue gas desulfurization device, and a chimney as shown in FIG. Each configuration is connected by piping or the like, and means for adjusting to a desired temperature or pressure is provided.

The operating conditions of the catalytic cracking reactor in the FCC apparatus are a reaction temperature of 400 to 600 ° C., preferably 450 to 550 ° C., a reaction pressure of normal pressure to 5 kg / cm ² , preferably normal pressure to 3 kg / cm ² , and a catalyst. / It is appropriate that the mass ratio of the raw material hydrocarbon oil is 2 to 20, preferably 4 to 15.

When the reaction temperature is 400 ° C. or higher, the decomposition reaction of the hydrocarbon oil proceeds favorably, and the decomposition product can be preferably obtained. Further, when the temperature is 600 ° C. or lower, the amount of light gas generated by decomposition such as dry gas and LPG can be reduced, and the yield of the gasoline fraction of the target product can be relatively increased, which is economical.

When the pressure is 5 kg / cm ² or less, the progress of the decomposition reaction of the reaction in which the number of moles increases is not easily inhibited. Further, when the mass ratio of the catalyst / raw material hydrocarbon oil is 2 or more, the catalyst concentration in the cracking reactor can be maintained at an appropriate level, and the decomposition of the raw material hydrocarbon oil proceeds suitably. Further, if it is 20 or less, the effect of increasing the catalyst concentration is saturated, and it is possible to avoid a disadvantage because the effect commensurate with increasing the catalyst concentration cannot be obtained.

Reaction tower 11
The reaction column 11 produces a decomposition product by bringing the raw material oil into contact with the catalyst and decomposing the raw material oil. The reaction tower is connected to, for example, a regeneration catalyst transport line for supplying the catalyst regenerated in the regeneration tower 12 and a feedstock oil supply line for supplying the feedstock oil. A pumping fluid is circulated in the reaction column, and the supplied catalyst flows in the reaction column 11 together with the pumping fluid. The raw material oil is preheated by a preheating device or the like, steam is added as needed, and then supplied to the reaction tower 11 from the raw material oil supply line. The raw material oil supplied into the reaction column 11 comes into contact with the catalyst and decomposes. The decomposition product produced by the decomposition of the raw material oil is extracted from the reaction column, rectified by a fractionator, and separated into necessary components.

In the catalytic cracking reaction, heavy oil is usually used as the raw material oil as described later, so that the reaction product is a gasoline base material, but this is not particularly limited.
The reaction tower is appropriately equipped with a cyclone, a decomposition product discharge line, a stripper and a used catalyst transport line in order to separate the decomposition product and the catalyst. Cyclones use centrifugal force to separate decomposition products from the catalyst.

In addition, the separated used catalyst is supplied to the stripper as needed. Steam is supplied to the stripper. In strippers, steam removes hydrocarbons on the catalyst, reducing the amount of cork on the catalyst. The used catalyst is discharged from the reaction tower from the used catalyst transport line and transferred to the regeneration tower 12.
In the present invention, a part of the used catalyst sent to the regeneration tower is extracted into a waste catalyst tank. Therefore, the used transport line may be provided with an outlet for the used catalyst.

(catalyst)
The catalyst brought into contact with the feedstock in the reaction column 11 includes the catalyst regenerated by the regeneration column 12. All of the catalysts brought into contact with the feedstock oil may be catalysts regenerated by the regeneration tower 12. Further, a part of the catalyst to be brought into contact with the raw material oil may be a new catalyst. Normally, in order to maintain the activity of the catalyst constant, a part of the catalyst circulating in the FCC device is extracted from the FCC device and a new catalyst is supplied to the FCC device. As described above, a catalyst in a state in which the activity of the catalyst is maintained constant is generally called an equilibrium catalyst.

The size of the catalyst to be brought into contact with the raw material oil is not particularly limited as long as it can flow in the FCC device and can be catalytically decomposed with the raw material oil, preferably having an average particle size of 40 μm or more, and usually 40 to 100 μm. Those in the range of are used.

The composition of the catalyst in contact with the feedstock comprises at least one zeolite selected from the group consisting of Y-zeolites, hyperstable Y-zeolites and ZSM-5 zeolites. The proportion of the zeolite in the catalyst is preferably 10% by mass or more and 40% by mass or less, preferably 15% by mass or more and 40% by mass or less, and more preferably 15% by mass or more and 35% by mass or less. Further, the catalyst to be brought into contact with the raw material oil may contain at least one selected from the group consisting of alumina, clay minerals and silica. In this case, for example, the proportion of alumina in the catalyst is preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 45% by mass or less. The proportion of clay minerals in the catalyst is preferably 80% by mass or less, more preferably 75% by mass or less, and further preferably 70% by mass or less. Further, the proportion of silica in the catalyst is preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 45% by mass or less.

(Raw material oil)
The raw material oil for the FCC apparatus can be used without particular limitation as long as it is normally used, and desulfurized heavy oil that has been hydrodesulfurized and hydrodecomposed in advance is preferable, for example, thermal decomposition desulfurized heavy oil, indirect desulfurized heavy oil, and the like. It is possible to directly use desulfurized heavy oil or the like.

(Pyrolysis desulfurization heavy oil)
The pyrolysis desulfurized heavy oil used as the raw material oil of the FCC apparatus according to the present embodiment is one or more of the atmospheric distillation residual oil and the reduced pressure distillation residual oil obtained by atmospheric distillation of crude oil. It is obtained by pyrolyzing and hydrolyzing the pyrolyzed heavy oil obtained by pyrolyzing under the above conditions with a pyrolyzing and desulfurizing apparatus.

(Conditions for thermal decomposition treatment)
The conditions of the pyrolysis treatment are not particularly limited, but usually, the pyrolysis temperature is preferably 490 to 510 ° C., particularly preferably 495 to 505 ° C., and the pressure (gauge pressure) during the pyrolysis treatment is. It is preferably 0.01 to 0.6 MPaG, and particularly preferably 0.05 to 0.4 MPaG. Also, the atmosphere of the pyrolysis treatment is steam. In addition, if excessive foaming is observed during the thermal decomposition treatment, an antifoaming agent may be added. As the defoaming agent, a silicon-based defoaming agent or the like can be generally used.

(Indirect desulfurization heavy oil)
The indirect desulfurized heavy oil used as the raw material oil of the FCC apparatus according to the present embodiment is obtained by hydrodesulfurizing heavy oil, vacuum gas oil, etc. obtained by atmospheric distillation of crude oil in the indirect desulfurization apparatus. Desulfurized heavy oil, desulfurized reduced pressure light oil, and desulfurized oil obtained by treating heavy oil with a solvent removing device can be used in combination.

(Direct desulfurization heavy oil)
The direct desulfurized heavy oil used as the raw material oil of the FCC apparatus according to the present embodiment has a high density of crude oil such as atmospheric pressure distilled residual oil, reduced pressure distilled residual oil, heavy light oil, catalytic cracking residual oil, and thermal cracking heavy oil. It is obtained by hydrodesulfurization and cracking in a heavy oil direct desulfurization apparatus using a petroleum distillate.

Hydrodesulfurization and hydrocracking to obtain direct desulfurization heavy oil are performed in the presence of a catalyst, and the desulfurization rate and weight required by optimizing the reaction conditions such as reaction temperature, reaction pressure, and liquid space velocity are required. The decomposition rate of quality oil can be achieved.

Hydrodesulfurization and hydrocracking in the desulfurization apparatus for obtaining the direct desulfurization heavy oil and the indirect desulfurization heavy oil are usually 3 to 20 MPa, preferably 5 under temperature conditions of usually 250 to 450 ° C., preferably 300 to 400 ° C. It is carried out under hydrogen pressurization of ~ 17 MPa. The liquid hourly space velocity (LHSV) is usually 0.1～3H ^-1, preferably 0.15～2.0H ^-1, a hydrogen / oil ratio is typically 1,000~3,000Nm ³ / KL, more preferably 1, It is carried out in the range of 500 to 2,500 Nm ³ / KL.

As the catalyst used for hydrogenation desulfurization and hydrocracking, any known catalyst having hydrogenation demetallization ability and hydrogenation desulfurization ability can be used, for example, alumina, silica-alumina, zeolite or a mixture thereof. As the carrier of the above, a catalyst carrying a Group 5 to 15 metal of the periodic table, or sulfides and oxides thereof can be used. As the metal of Group 5 to 15 of the periodic table, nickel, cobalt, molybdenum, tungsten or the like, or a combination thereof is preferably used from the viewpoint of using an active metal suitable for hydrodesulfurization. In the present invention, Co-Mo, Co-Mo- is used as a catalyst on a porous inorganic oxide carrier such as alumina because of its superior hydrodesulfurization, hydrocracking and hydrogenation ability with respect to heavy oil. It is preferable to use a catalyst supporting a metal such as P, Ni-Mo, Ni-Mo-P.

(Decomposition product)
The decomposition products discharged from the reaction column 11 are washed and rectified by, for example, a main distillation column (also referred to as a main distillation column). As a result, it is separated into liquefied petroleum gas (LPG), gasoline (FCCG), cracked gas oil (LCO), cracked heavy oil (HCO), and slurry oil (SLO).

Regeneration tower 12
The regeneration tower 12 regenerates the catalyst by burning the cork on the used catalyst separated in the reaction tower 11. The regeneration tower 12 may include, for example, a heating means, an air blower, an air grid, a cyclone, a regeneration catalyst transport line, and an exhaust gas line. Air is supplied from the air blower to the air grid, and air is supplied from the air grid into the regeneration tower 12. Further, the used catalyst is supplied to the regeneration tower 12 from the used catalyst transportation line. When air is supplied into the regeneration tower 12, the cork on the catalyst burns and the catalyst is regenerated. In the regeneration tower 12, for example, the used catalyst is regenerated at a temperature of about 600 to 800 ° C. The regenerated catalyst and the exhaust gas generated by the combustion of cork are separated by a cyclone. The regenerated catalyst is discharged from the regeneration tower 12 and supplied to the reaction tower 11 by the regeneration catalyst transport line. The exhaust gas is discharged from the regeneration tower 12 by the exhaust gas line. The exhaust gas contains CO ₂ gas and SOx gas as main components, and a small amount of catalyst not separated by a cyclone is also emitted.

In the present invention, the used catalyst sent to the regeneration tower is introduced into the exhaust gas flow path in the waste heat boiler. For this reason, the regeneration tower 12 or the used catalyst transport line is provided with a used catalyst outlet.

The used catalyst has an average particle size of 40 μm or more, and is usually in the range of 40 to 100 μm. When it is put into the exhaust gas flow path in the waste heat boiler, the effect is more preferably 60 to 80 μm. Usually, the used catalyst is about the same as the equilibrium catalyst, or a plurality of catalysts are aggregated to increase the particle size. Further, as the used catalyst, a catalyst having a bulk density in the range of 0.70 to 0.90 g / ml is used. By using a used catalyst in this range, it is possible to remove the scale of the catalyst accumulated in the exhaust gas flow path in the waste heat boiler, and it is possible to operate the FCC device stably for a long period of time. Become.

Waste heat boiler 13
The exhaust gas from the regeneration tower is passed through the waste heat boiler 13, and the amount of heat of the exhaust gas discharged from the regeneration tower is recovered. In the waste heat boiler 13, the amount of heat is recovered by heating the cooling medium from the heat of the exhaust gas by heat exchange, but water is usually used as the cooling medium and the heat is recovered as steam or hot water. Is the target. Typically, the waste heat boiler uses a shell-and-tube heat exchanger having a plurality of heat exchange tubes in which inner tubes (tubes) are arranged in a cylindrical shell.

The exhaust gas from the regeneration tower 12 flows through the inner pipe as a flow path, and water as a cooling medium is passed through the shell and recovered as steam. The recovered steam is reused as a heat source. Normally, the exhaust gas temperature at the waste heat boiler inlet is usually 600 to 800 ° C., but at the waste heat boiler outlet, it is cooled to about 150 to 300 ° C.

A heat transfer member such as a cooling fin is provided in the inner pipe for the purpose of increasing the heat transfer area. The cooling fin has a rectangular cross section, and the heat transfer area is increased to increase the amount of heat transfer and disturb the flow. Give to improve heat transfer coefficient. One aspect of this is a turbulence promoter and the like.

In the present invention, the used catalyst recovered in the waste catalyst tank is put into the exhaust gas flow path. The charging equipment is not particularly limited, but the used catalyst may be introduced by installing a nozzle in the flow path and using a pressure pot or the like.

The input amount of the used catalyst is preferably 0.5 to 2.0 vol-ppm, preferably 0.7 to 1.2 vol-ppm, with respect to the amount of waste heat boiler exhaust gas. The frequency of addition is not particularly limited, but it may be added continuously or intermittently, for example, at least once a week.

When the used catalyst is put into the exhaust gas flow path, only the accumulated scale is removed, and the amount of the used catalyst put into the exhaust gas amount of the waste heat boiler is small, so the inside of the inner pipe and the heat transfer member are not scraped. High heat exchange efficiency in the waste heat boiler can be maintained. In the present invention, the used catalyst is charged into the exhaust gas flow path, but it is also possible to charge a regenerated catalyst or a new catalyst, which has the same effect as the present invention, but costs, cooling means, and charging route. It is desirable to use a used catalyst in terms of design and the like.

In addition, a predetermined amount of used catalyst may be added on a regular basis, and the exhaust gas temperature at the waste heat boiler outlet and the amount of catalyst scattered from the regeneration tower are calculated from the amount collected from the electrostatic collector and monitored. It is also possible to add a used catalyst when the temperature or the amount of catalyst rises. Furthermore, during continuous operation using the heat transfer calculation program of HTRI (Heat Transfer Research, Inc.), the waste heat boiler inlet temperature, outlet temperature, and corrected U value (total heat transfer coefficient) are measured, and these data changes. From the above, it may be determined that the used catalyst is charged, and for example, when the corrected U value or the outlet temperature rises, the used catalyst may be charged into the exhaust gas flow path. This allows the waste heat boiler to be cleaned online without shutting down the FCC device.

Exhaust gas that has passed through a waste heat boiler is collected by an electrostatic precipitator to collect used catalysts and desorbed deposits, and then processed via a flue gas desulfurization device. From the chimney according to environmental standards. It is discharged into the atmosphere or reused. In addition, before passing the exhaust gas through the electrostatic precipitator, coarse particles can be removed with a gravity precipitator, an inertial precipitator, a centrifugal precipitator (cyclone), etc., a cleaning dust collector (scrubber), and filtration. A dust collector (bug filter) or the like may be used together.

By adopting the continuous operation method of the flow contact cracking apparatus of the present invention, the above-mentioned cleaning effect in the exhaust gas flow path is brought about online, and the labor of cleaning the waste heat boiler accompanied by the shutdown of the FCC apparatus is achieved. And the problem of reduced production volume is also solved.

[Example]
Hereinafter, one embodiment of the present invention will be described with reference to Examples, but the present invention is not limited to these Examples.

Contact cracking was carried out as follows.
As the raw material oil, a density of 0.85-0.95, sulfur: 0.29% by mass, residual coal: 3.0% by mass or less is used, and the following operating conditions are used using the FCC apparatus shown in FIG. The raw material oil was catalytically cracked in. Since the reaction was carried out in plant equipment, the reaction conditions were not strictly constant, and were appropriately adjusted so as to be within this range.
Reaction temperature: 508-515 ° C
Reaction pressure: 0.1 to 0.3 MPaG
Regeneration tower temperature: 732-737 ° C

A commercially available FCC catalyst was used as the catalyst. The average particle size of the equilibrium catalyst in the FCC apparatus was 68 μm. The average particle size of the used catalyst sent to the waste catalyst tank was 70 to 74 μm.
As a waste heat boiler, a heat exchanger was used in which exhaust gas was passed through a tube and industrial water was passed through a shell. The inner diameter of the tube was 38.8 mm, 540 tubes were arranged in the shell, and the tube inlet flow velocity was 35 to 38 m / sec.

Examples and Comparative Examples Exhaust gas was treated with a waste heat boiler for 3 months. In the examples, a used catalyst having a charging frequency of 1 time / week, a charging amount of 42.5 kg / time (50 L / time), and a bulk density of 0.85 g / ml is 0.8 vol-ppm in the exhaust gas. So put it in. In the comparative example, the waste heat boiler was operated under the same conditions without adding a used catalyst. Table 1 shows the average of the values measured by HTRI for 3 months.

From Table 1, in the operation of the example in which the used catalyst is passed through the tube of the waste heat boiler under the same operating conditions, the outlet temperature is low, the amount of heat exchanged in the waste heat boiler is large, and the U value is 60 kcal / m ^2.・ The temperature has been increasing by about ℃ ・ h, and the amount of steam generated has been increasing by about 3 T / h.

Further, FIG. 2 shows a change in the U value (total heat transfer coefficient) of the waste heat boiler with respect to the operation period. From FIG. 2, in the operation under the conditions of the comparative example, the heat transfer is reduced due to the contamination due to the catalyst deposition, but the initial U value can be maintained by adding the used catalyst as in the example. ..

Normally, the overall heat transfer coefficient of the waste heat boiler begins to decrease and the catalyst scattering rate begins to increase from about 2 weeks after the start of operation, but it is summarized by regularly introducing the used catalyst into the flow path. The heat transfer coefficient can be returned to the initial value, the accumulated catalyst is removed, and the accumulation of newly scattered catalyst is suppressed, so that the heat exchange efficiency of the waste heat boiler can be maintained high.

Since the inlet pressure to the electrostatic precipitator can be kept low, the electrostatic precipitator can be maintained at a high efficiency. Further, since the waste heat boiler outlet temperature changes at a low level, the pressure in the flue gas desulfurization apparatus changes at a low level, which enables continuous operation for a long period of time and saves energy in the flue gas treatment itself.

According to the present invention, since heat transfer in the waste heat boiler flow path at the initial stage of FCC operation can be maintained for a long period of time, the amount of energy saving is high, and the crude oil conversion unit is about 700 COE-KL / year, about 40 million yen / year. Can achieve energy saving.

According to the present invention, the cleaning effect in the exhaust gas flow path is brought about online, and the problem of cleaning the waste heat boiler accompanied by the shutdown of the FCC device and the resulting decrease in production amount is solved. Therefore, it is possible to provide a continuous operation method of the fluidized catalytic cracking apparatus that stably cracks the feedstock for a long period of time.

1 FCC device 11 Reaction tower 12 Regeneration tower 13 Waste heat boiler

Claims (3)

In a reaction tower that produces a decomposition product by bringing the raw material oil into contact with the catalyst and decomposing the raw material oil, a regeneration tower that regenerates the catalyst by burning the separated coke on the catalyst, and a regeneration tower. Equipped with exhaust gas recovery means
In a fluidized catalytic cracking apparatus for raw material oil, the obtained regeneration catalyst is circulated in a reaction tower and continuously operated.
A waste heat boiler is included as an exhaust gas recovery means, and the amount of heat of the exhaust gas discharged from the regeneration tower is recovered, and a part of the used catalyst sent from the reaction tower to the regeneration tower is extracted into the exhaust gas flow path in the waste heat boiler. , A method for continuously operating a fluidized catalytic cracking apparatus, which comprises charging a part of a used catalyst. The continuous operation method of the fluid cracking apparatus according to claim 1, wherein the used catalyst to be charged has an average particle diameter of 40 μm or more. The first aspect of the present invention, wherein the used catalyst is charged at least once a week so that the amount of the catalyst charged is 0.5 to 2.0 vol-ppm with respect to the amount of waste heat boiler exhaust gas. A method for continuous operation of a flow contact cracking device.