JPS594745Y2 - Spouted layer particle fall prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for preventing solid particles circulating in a spouted bed from falling into a gas artificial nozzle during shutdown.

Generally, when a spouted bed is used for drying, granulation, pyrolysis reactions, heat exchange, etc., when the operation is stopped, that is, when gas injection stops, the particles circulating in the bed are removed from the inlet gas pipe. The problem was that the battery could fall into the tank, causing a blockage and making it difficult to restart.

There is no suitable method for preventing particles from falling, and the only method that has been adopted is to create a pipe shape that will not cause blockage even if particles fall.

That is, as shown in FIG. 1, the gas inlet nozzle is T-shaped, and the solid particle storage tank is installed below it.

In FIG. 1, gas 1 enters a T-shaped nozzle 2, changes its direction upward in the T-shaped nozzle 2, rises through the center of the spouted bed 3, and the particles and gas are separated by the collision plate 4. 6 is discharged to the outside.

During operation, the solid particles circulate in the spouted bed 3, but when the operation is stopped, the solid particles fall from the T-shaped nozzle 2 and are temporarily stored in the storage tank 7.

At the start of operation, gas is first passed through the spouted bed, and then the solid particles in the storage tank 7 are transported to the upper separation storage tank 11 by the rotary feeder 8, ejector 9, and transport pipe 10, and the solid particles are transported to the upper separation storage tank 11 by the rotary feeder 8. 12 to the spouted bed 3.

Note that FIG. 1 shows a system using air as the transport medium 13.

However, in the case of this method, (1) a solid particle storage tank (with a capacity that can accommodate all of the amount stored in the spouted bed), (2) a particle transport facility (a solid particle storage tank with a capacity that can accommodate the entire amount stored in the spouted bed) It is necessary to newly install equipment (equipment) outside the spouted bed, which not only increases the cost of the equipment but also is complicated and cannot be called an economical method.

On the other hand, gas is used as a cooling heat exchanger to effectively recover the sensible heat possessed by dirty gases such as coal, heavy oil, and other high-temperature pyrolysis gases that contain large amounts of coking substances such as tar, pitch, and carbon. The use of a fluidized bed having a dispersion plate causes clogging due to coking of the dispersion plate, making continuous operation over a long period of time extremely difficult, and is therefore unsuitable for practical use.

Therefore, it is necessary to change to a fluidized bed without a dispersion plate, that is, a spouted bed, and the spouted bed can sufficiently exhibit basic performance such as suppression of coking on heat exchanger tubes and self-regeneration of solid particles.

Normally, this spouted bed heat exchanger should be inspected by stopping its operation.
Although it is not necessary to perform operations such as decoking, the gas generation side (e.g., cracking furnace, etc.) may be shut down for regular repairs or overhaul inspections, and in this case, the subsequent heat exchanger will also be shut down. It is necessary to maintain the condition.

In addition, when applying this spouted bed type to a quenching heat exchanger for ethylene production, it is essential to install the quenching heat exchanger directly above the cracking furnace to ensure process performance. It is difficult to employ a conventional T-shaped nozzle as shown in FIG. 1 because of the occurrence of coking due to sudden bends in the gas and the extension of cooling time.

As mentioned above, in spouted bed heat exchangers, etc., gas generation is intermittent, making it necessary to stop and start the heat exchanger at short intervals, and it is difficult to use a T-shaped nozzle due to the layout. First, if the operation is stopped, solid particles may fall into the cracking furnace, making restarting difficult.

This invention provides a device that prevents particles from falling with simple operation, and not only contributes to labor saving and equipment cost reduction, but also provides a nozzle that matches both plant layout and process performance. The present invention provides the above-mentioned device which also has the effect that the shape can be selected.

That is, the present invention includes a slit that is fixed in communication with the gas inlet nozzle in the spouted bed and has a plurality of openings on the circumferential surface of the tube at intervals in the circumferential direction of the tube, and a slit that opens or closes the openings by rotation. and a rotatable draft tube installed concentrically on the outer periphery of the slit tube and having openings spaced apart from each other on the lower circumferential surface so as to prevent particles from falling in a spouted bed. It is something.

FIG. 2 is an explanatory diagram showing an embodiment of the device of the present invention (here, the state in operation is shown), and FIG. 3 is a detailed view of the slit pipe 38 in FIG. 2, where A is a plan view and B is a plan view. The side view and FIG. 4 are detailed views of the draft tube 24 in FIG. 2, where A is a plan view and B is a side view.

2 to 4, the hot gas 21 enters the spouted bed heat exchanger 23 through the gas inlet nozzle 22 and passes through the slit tube 38 having an opening 38' and the draft tube 24 having an opening 24' at the bottom. The gas gradually rises in a solid-air mixed phase state, changes direction at the collision plate 26, passes between the hangers 25, and is guided to the outside as a cooling gas 32 through the gas outlet nozzle 31.

The heat lost by the gas is first transferred to the solid particles 36, and then transferred to the water 34 flowing through the heat transfer tube 33 while the solid particles 36 are descending, and is recovered in the form of steam 35.

During this operation, the opening 38' of the slit tube 38 and the opening 24' at the lower part of the draft tube 24 are in a completely overlapping state, and the solid particles 36 that have descended are transported through both openings 24'.
, 38' into the draft tube 24 to form a circulating flow.

In the device of the present invention, the operation is stopped and started by the following operations.

First, when the operation is stopped, while cooling the high-temperature gas as described above, the rotary shaft 27, collision plate 26, hanging tool 25, and draft tube 24 are integrated, and the integrated structure is driven into the slit pipe 38 by the drive motor 30. The gas blowing is stopped when the opening 38' and the opening 24' of the draft tube 24 are rotated to a completely closed position and the solid particles 36 no longer circulate.

Note that a pedestal 29 for fixing the rotating shaft 27 and an airtight device 28 for maintaining a seal between the inside of the spouted bed 23 and the outside are provided.

Next, when starting the operation, after blowing in a predetermined amount of high-temperature gas, the integrated structure of the rotating shaft 27, collision plate 26, hanging tool 25, and draft tube 24 is inserted into the opening 3 of the slit pipe 38.
8' and the opening 24' of the draft tube 24 are rotated to an open position where they overlap, forming a circulating flow of solid particles 36.

According to the device of the present invention described above, the following effects can be achieved.

(1) The shape of the gas feed line leading to the gas inlet nozzle can be selected to be the most desirable shape in terms of process performance and layout.

(2) Since no solid particles are discharged to the outside, particle storage tanks and transportation and supply equipment are completely unnecessary.

(3) Particles can be prevented from falling with a very simple operation.

(4) At the start of operation, the increase in supply gas pressure is also eliminated.

The relationship between the pressure change ΔP and the air volume when the charge amount is constant is as shown in FIG.

In FIG. 5, the dotted curve 1 is the case when the device of the present invention is used, and the solid line curve 2 is the case when the conventional device shown in FIG. 1 is used.

(5) By rotating the draft tube integrally with the collision plate, the clearance between the draft tube and the collision plate is always kept constant, so that the jet stream is always maintained in a stable and good condition.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a conventional spouted bed heat exchanger, Figure 2 is an explanatory diagram of the device of the present invention, Figures 3A and B are detailed diagrams of the slit pipe 38 in Figure 2, Figure 4A, B is a detailed view of the draft tube 24 in Fig. 2, and Fig. 5 shows the relationship between pressure change and air volume.
This is a chart comparing the cases in Figure 2 and Figure 2.

Claims (1)

[Scope of utility model registration request] a slit fixed in communication directly above the gas inlet nozzle in the spouted bed and having a plurality of openings on the circumferential surface of the tube at intervals in the circumferential direction of the tube; and a slit configured to open or close the openings by rotation. A spouted bed particle fall prevention device comprising: a rotatable draft tube having openings at intervals on a lower circumferential surface and installed concentrically on the outer periphery of the slit tube.