JPH01307441A - Method for fluidizing stationary powder-packed bed - Google Patents

Abstract

PURPOSE:To smoothly carry out fluidization and to prevent the flying out and damage of powder by providing separate gas inlets in the stationary powder- packed bed in a vessel, and gradually transferring the gas inlet from the upper part toward the lower part when fluidization is started. CONSTITUTION:In the device for fluidizing the stationary powder-packed bed in the vessel of a fluidized-bed reactor, etc., the powder 2 is packed into the vessel 1, and a gas diffusion plate 3 for supporting the packed bed and uniformly diffusing the gas is provided. Three gas inlets 5-7 are separately provided. When fluidization is started, the valve of a passage 4 is firstly opened to exert an appropriate pressure on the diffusion plate 3, the uppermost passage 7 is then opened little by little to produce a pressure in the upper space of the powder, and the caked powder in the space is disintegrated and fluidized. The passages 6 and 5 are then successively opened. By this method, fluidization is smoothly carried out, and the flying out and damage of the powder are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for fluidizing static powder filled in a container.

The method of the present invention is applicable to fluidized bed reactors and various devices that handle powder.

(Prior art and its problems) In a fluidized bed reactor or a device that fluidizes and transfers powder, a gas dispersion plate is usually provided at the bottom of a stationary powder packed bed.
The powder is fluidized by introducing gas from the bottom.

When the reaction is carried out at a temperature higher than room temperature, such as in a fluidized bed reactor, and the temperature drops when stopping, or when the packed bed of stationary powder is high, by keeping the body in a stationary state for a long time. Consolidation progresses due to a decrease in temperature, compaction due to the powder's own weight, or the adhesive force of the powder.

When performing an operation to start fluidizing the powder from such a solidified state, the following phenomenon occurs in the conventional method of introducing gas from the bottom of the packed bed.

(1) For the gas introduced from the bottom of the packed bed, most of the force that initially pushes up the powder is absorbed by the wall surface of the container and the surface of the interior components, so the force for disintegrating the solidified powder is small. For this reason, the gas introduced from the bottom of the packed bed requires a considerably high pressure.

(2) Collapse of the solidified powder occurs suddenly, and at that moment a large amount of powder flies out from inside the container and is discharged to the outside of the system. This contaminates the filters and heat exchangers used in the next process, causing them to lose their functionality.

(3) At the moment when the solidified powder collapses, a sudden pressure change occurs in the container, and the impact flow damages internal components such as heat exchanger tubes and separators, as well as the filter.

(Means for Solving the Problems) The inventors were engaged in the development of a fluidized bed methanol synthesis reactor, and as a result of intensive study on the above-mentioned problems at the start of fluidization of a powder catalyst, the inventors developed a powder packed bed methanol synthesis reactor. These problems can be solved by separately providing one or more gas inlets inside the powder bed and moving the gas inlets gradually from the top to the bottom when fluidization starts, rather than from the bottom of the powder packed bed. This discovery led to the present invention.

That is, the present invention separately installs one or more gas inlets in a stationary powder packed bed filled in a container, and sequentially introduces gas from the gas inlet in the uppermost layer to the gas inlets below. This is a unique method for fluidizing a static packed bed of powder.

The method of the invention is particularly effective when the packed bed of stationary powder is high. The height of the packed bed of stationary powder employed in the method of the present invention varies depending on the physical properties of the powder, such as particle size, density, and stickiness, but is generally 2 m or more. Filling height is 2
If it is less than m, the above-mentioned problems are unlikely to occur, except in the case of highly adhesive powder.

The number of gas inlets to be installed depends on the physical properties of the powder and the filling height as described above, but in general, 1 to 3 gas inlets are installed for a stationary powder packed bed.
It is desirable to provide a gas inlet every m, and especially for powders that tend to solidify due to their own weight, it is preferable to reduce the interval between the gas inlets at the bottom of the packed bed.

The amount of gas introduced at each gas inlet is determined by the gas superficial velocity (Do (m/s)) in the packed bed section, the powder fluidization velocity (O
ar (m/s)). This gas superficial velocity (Do (m/s)) is generally less than 0.01 m8. The gas introduction method is to first introduce the required amount of gas into the gas inlet at the top, fluidize the area above this gas inlet, then open the gas inlet at the next height, and then Fluidize the layer. In this way, the gas inlets are sequentially moved to the lower part, and finally the entire powder packed bed is fluidized. Depending on the amount of gas to be introduced into the packed bed, the fluidization characteristics of the powder, etc., the valve above the gas inlet to be introduced at each stage is closed at any time as necessary. Particularly in a fluidized bed catalytic reactor, in order to increase the efficiency of the fluidized catalyst bed, valves other than the gas inlet at the bottom of the packed bed are closed after fluidization is completed.

Next, the present invention will be explained using the drawings. FIG. 1 is an explanatory diagram when a powder packed bed is fluidized by the method of the present invention. In FIG. 1, a cylindrical container 1 is filled with powder 2 and is provided with a gas dispersion plate 3 for supporting this powder-filled layer and uniformly dispersing gas. During normal operation, gas is supplied through channel 4, but three gas introduction channels 5, 6, and 7 are provided in the stationary powder packed bed.

This figure shows the powder in a static state, and next, the procedure for starting fluidization according to the present invention will be explained.

After all the valves provided in the flow paths 4 to 7 are closed, the valve of the flow path 4 is opened to apply an appropriate pressure to the gas distribution plate 3. Next, open the channel provided in the uppermost channel 7 little by little,
Pressure is generated between the valve and the space above the powder to break up the solidified powder in this section and form a gently fluidized state. Subsequently, by opening the valve of the flow path 6, the section between the flow path 7 and the flow path 6 is fluidized. In this case, the valve of the flow path 7 is closed as necessary. Furthermore, by opening the valve of the flow path 5, the solidified powder is destroyed and fluidized in order from the upper layer in the section between the flow path 6 and the flow path 5, and finally the section of the flow path 5 is fluidized.
Fluidize the entire stationary powder packed bed.

(Example) Next, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to this example.

In a fluidized bed type methanol synthesis reaction vessel with an inner diameter of 1.0 m and a height of 18 m, a stationary powder packed bed was fluidized according to the flow shown in Fig. 1. Powder catalyst has a particle size of 10 to 15
A copper-based catalyst having a particle size distribution of 0 μm and a bulk specific gravity of 1.2 kg/l was used and packed as a stationary packed bed at a height of 8 m on a gas distribution plate. The gas introduced into this reactor is a synthesis raw material gas whose main components are hydrogen and carbon monoxide.
Methanol was synthesized under a pressure of ~150 kg/cm2G.

The height of each gas introduction channel from the gas distribution plate was determined as follows. In addition, as a result of measuring the powder pressure in the stationary packed bed, it was almost the same within 4 m from the top, so the sections from the dispersion plate to the flow path 5 and from the flow path 5 to the flow path 6 were made equal.

The above-mentioned reactor, which had been in a stationary state for 10 days after being charged with the catalyst, was closed to start fluidization, and the valve of flow path 4 was opened, and the pressure in the reactor space was lowered to 1.0 k.
The pressure in the flow path 7 was then opened and the synthesis raw material gas was introduced, and the pressure in this flow path became 0.5 kg/cm2 higher than the pressure in the reactor space. The pressure difference is 0.36 kg/cm.
It became constant at 2, and it was confirmed that the solidified catalyst above this flow path collapsed and fluidization started. Similarly, the channels 6, 5, and 4 were sequentially operated to disintegrate and fluidize the solidified catalyst. The peak pressure difference and steady pressure difference due to the response operation were as follows.

As a result, the entire powder catalyst packed bed was smoothly fluidized, and during this operation, no catalyst particles were ejected from the reactor at all, and there was no effect on the next step of Nifilon and catalyst filter.

In Example 1, flow path 7. Channel 6. When the feedstock synthesis gas was introduced only from flow path 4 and the powder catalyst packed bed was fluidized with the flow path 5 closed, the pressure difference with the reactor space exceeded 71 tg/cm. reached, and the solidified catalyst suddenly collapsed.As a result, the heat exchanger tubes in the reactor were damaged, the cyclone was overloaded, and the catalyst filter was severely contaminated.

(Effects of the Invention) When a stationary powder packed bed is fluidized by the method of the present invention, the fluidization is performed very smoothly, and powder flying out of the container and damage to the contents inside the container are prevented. This makes it possible to start up a fluidized bed reactor etc. easily and safely, and the present invention has great industrial significance.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram when a powder packed bed is fluidized by the method of the present invention. ■=Container, 2: Stationary powder packed bed, 3: Gas dispersion plate Patent applicant Mitsubishi Gas Chemical Co., Ltd. Agent Patent attorney Makoto Kobori Text 1 recessed procedure master's letter (self-motivated) 1985-28 Day

Claims (1)

[Claims] A stationary powder characterized in that one or more gas inlets are installed separately in a stationary powder packed bed filled in a container, and gas is introduced sequentially from the gas inlet in the uppermost layer to the gas inlets below. Fluidization method for body packed bed