JPS6022969B2 - Powder circulation equipment - Google Patents

Description

[Detailed description of the invention] The present invention relates to a granular material circulation device.

In petrochemical and other industries, it is sometimes necessary to circulate powder and granules to reaction towers and the like as catalysts and heat carriers.

Conventionally, methods for transporting high-temperature powder and granular materials include methods such as utilizing a level difference between powder and granular layers, utilizing a pressure difference between powder and granular layers, pneumatic transport, or a combination thereof.

Also, in these cases, the means to control the flow rate of powder and granular material include using special valves such as slide valves to control the flow rate by controlling the valve, and installing a large number of nozzles in the middle of the transport pipe to blow aeration gas. Control, etc., is performed using changes in the density of powder or granular materials due to this.

When valve control is adopted, a valve that can withstand the high temperature is required in the high temperature section, but it is expensive, and in addition, there are various problems such as gas sealing, abrasion due to the entrapped powder and granules, and so on.

Control using aeration gas requires the installation of a large number of nozzles for aeration, and there is a problem in that considerable skill is required in operating operations such as balancing air supply to the nozzles. The present invention aims to improve these drawbacks and propose a device that is easy to control.

FIG. 1 shows a fluid catalytic cracking apparatus according to an embodiment of the present invention, which is used in the petroleum refining industry for catalytic cracking of vacuum gas oil and the like.

1 is a reactor using a fluidized bed for catalytic reaction, and 2 is a regenerator having a fluidized bed for regeneration.

The catalyst powder (hereinafter referred to as powder) in the reactor 1 is brought into a fluidized state by the fluidizing gas that enters from the gas inlet 4 and is supplied through the dispersion plate 5, while the catalyst powder and granules in the reactor 1 are brought into a fluidized state by the fluidizing gas that is supplied from the feed oil inlet 6. A catalytic cracking reaction is carried out by mixing with vacuum gas oil. on the other hand,
A part of the powder in the reactor falls into the stripper 7 through the gap between the dispersion plate 5 and the reactor main body 1, where it is passed through a stripping steam inlet 8 for removing oil adhering to the hot powder. It enters the connecting pipe 9 while being stripped by the stripping steam supplied from the source. Aeration gas supplied from an aeration gas inlet 10 for flowing powder and granules attached to the lower part of the communication pipe 9 controls the flow rate of the powder and granules flowing down the communication pipe 9. The powder and granular material whose flow rate is controlled by the aeration gas is airflow-transported within the lift pipe 12 by the lift gas supplied from the lift gas inlet 11 to the regenerator 2 having the high-level fluidized bed section 3a.

In this case, it is possible to control the flow rate of the powder by the amount of lift gas, but if the amount of lift gas is smaller than the amount of powder transported, there is a risk of clogging of the IJ foot pipe. The operation becomes unstable and the amount of lift gas needs to be varied greatly. On the other hand, when the aeration gas is used for control in the position of the present invention, the amount of the aeration gas is small and the amount of variation is also extremely small. The powder and granules that have entered the regenerator 2 are sent to the combustion air inlet 1.
3 and through the dispersion plate 14, the carbon adhering to the surface of the powder is combusted in the regenerator.
A part of the powder in the high-level fluidized bed section 3a in the regenerator 2 is transferred to the transport pipe 1.
5 and passes through a cross-section reduced section 16 for controlling the flow rate of powder and granular material, where a flow rate control gas nozzle 17a and a deceleration gas nozzle 17 are connected.
The flow rate is controlled by the flow rate control gas supplied from b and is returned to the reactor 1 having the lower fluidized bed section 3b.

As described above, the catalyst powder 3 is used by being circulated between the reactor 1 and the regenerator 2.

When the flow rate control of the two circulation lines is not performed, if the amount of powder and granules transported through the transport pipe 12 is greater than the amount transported through the transport pipe 15, the amount of powder and granules in the reactor 1 gradually decreases and reacts. The height of the fluidized bed in vessel 1 decreases.

Therefore, the oil that has been crushed through the feedstock oil inlet 6 has a short after-contact time and exits the reactor 1 through the outlet 18 unreacted. In the opposite case, the amount of powder and granules transported into the regenerator 2 is insufficient, and therefore the amount of carbon to be combusted decreases, and the temperature inside the regenerator 2 decreases.

By implementing the present invention, it is possible to easily control the flow rates of powder and granular material in the two transport pipes, so that the apparatus can be operated safely and efficiently.

The detailed structure of the flow rate control sections of these two transport pipes will be explained below.

2 and 3 also show the cross section of the reduced section section 16 that controls the flow rate of the transport pipe 15, and the granular material flowing down the transport pipe 15 enters the reduced section section 16.

Here, the flow rate is controlled by the flow rate control gas supplied from the flow rate control gas inlets 17a and 17b. The control characteristics of this flow rate control section are shown in FIG. Code WN in the figure
^x indicates a large powder flow rate, and Wo indicates a powder flow rate setting value. If you want to reduce the transport amount by setting the reduction section so that it is not necessary to supply the control gas at the currently set powder flow rate, you can reduce the downstream gas pressure by supplying the control gas from the downstream nozzle. To increase the amount of transportation, control gas is supplied from the upstream side, thereby increasing the gas pressure on the upstream side and increasing the amount of transportation.
4 and 5 show the detailed structure of the flow rate control section of the transport pipe 12.

The particles flowing down the communication pipe 9 have their apparent cage density reduced by the aeration gas from the aeration gas inlet 10, and the particles with reduced friction between the particles enter the transport pipe 12. At this time, the apparent density and the friction between the powder particles change depending on the amount of aeration gas blown in, and the flow rate is controlled. FIG. 7 shows the flow rate control characteristic curve of this part. When the connecting pipe 9 is installed straight to the transport pipe 12 as shown in FIG. 4, the control characteristic becomes curve a in FIG. 7. When the connecting pipe 9 is bent and attached to the transport pipe 12 as shown in Fig. 5, the control characteristic becomes as shown in Fig. 7b, and the flow rate becomes zero even without a valve. In the figure, the symbol WN^x indicates the maximum flow rate of the powder and granular material, and Xo indicates the set value of the flow rate of the powder and granular material. In short, in a device that connects two fluidized bed containers and circulates powder and granules, an aeration nozzle is installed at the connection with the lower end communication pipe of the lower fluidized bed container and the lift pipe to supply gas to the aeration nozzle. A granular material circulation device characterized in that a speed increasing gas/zzle and a decelerating gas nozzle are provided in a reduced cross-section section at the center of an inclined transport pipe connecting a higher fluidized bed section and a lower fluidized bed section. By proposing this, it is possible to smoothly circulate the powder between the reactor and the regenerator and easily control the flow rate.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the device according to the present invention, FIG.
4 and 5 are cross-sectional views of the flow rate control section of the present invention, and FIGS. 6 and 7 are diagrams showing the effects of flow rate control. 1...Reactor, 2...Regenerator, 3a...High-level fluidized bed section, 3
b...low fluidized bed section, 4...gas inlet, 5...dispersion plate, 6...raw oil inlet, 7...stripper, 8...
・Stripping steam inlet, 9...Connecting pipe, 10...
・Aeration gas inlet, 11... Lift gas inlet, 12... Air lift pipe, 13... Combustion air inlet,
DESCRIPTION OF SYMBOLS 14... Dispersion plate, 15... Transport pipe, 16... Cross section reduction part, 17a... Enhancing gas nozzle, 17b... Deceleration gas nozzle, 18... Reactor outlet, 19... Regenerator outlet. Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1 In a device that connects two fluidized bed containers and circulates powder and granular materials, an aeration nozzle is provided at the connection between the lower end communication pipe of the lower fluidized bed container and the lift pipe, and the gas supplied to this aeration nozzle is controlled. A granular material circulation device characterized in that a speed-increasing gas nozzle and a decelerating gas nozzle are provided in a reduced cross-section section at the center of an inclined transport pipe connecting a high-level fluidized bed section and a low-level fluidized bed section.