JPS62183849A - Peripheral wall jet stream type fluidized bed apparatus - Google Patents

Abstract

PURPOSE:To make it possible to regulate the stagnation amount and flow condition of a particulate material by changing the flow speed of a rising gas stream without changing the amount of gas, by providing an opening part having an area variable structure for blowing up the rising gas stream between the inner peripheral wall and fluidized bed bottom plate of a vertical cylindrical container. CONSTITUTION:The particulate material supplied in a fluidized bed apparatus from a supply port 2 forms a fluidized bed and a jet stream layer by the rising gas stream blow up from an opening part 8 to receive drying, reaction and cooling treatments. Herein, by regulating the opening area of the opening part 8 by area regulating plates 7a-8b mounted in a freely slidable manner so as to be made operable from the outside or a fluidized bed bottom plate 6'' formed in an up-and-down movable manner, the flow speed of the rising gas stream can be increased and decreased even if the amount of gas is constant and, therefore, the stagnation amount of the particulate material can be arbitrarily regulated within a certain range. If the particulate material is supplied continuously, said material continuously falls by the amount corresponding to the increase in the stagnation amount to be discharged.

Description

Detailed Description of the Invention: Industrial Field of Application This invention is a method for drying and roasting powder by forming a fluidized bed or spouted bed of rising air and powder in a vertical cylindrical container. ,reaction,
The present invention relates to a fluidized bed apparatus used for catalytic reactions of gas components in ascending air or fluidized bed treated with sintering, cooling, etc.

BACKGROUND OF THE INVENTION 2. Description of the Related Art Fluidized bed apparatuses are used to treat various types of powder and granular materials to take advantage of their excellent properties. However, since it has many mechanical shortcomings, various improvements have been proposed. A typical example is the device shown in FIG. In this device, granular material is supplied from a raw material supply port 12 of a fluidized bed device main body 11, and the treated granular material is overflowed and discharged from a discharge port 13. On the other hand, the rising air current is supplied from the inlet 14, is dispersed by the porous plate 15, rises, forms a fluidized bed 16 with the powder, and is then discharged from the outlet 17.

In the type shown in Fig. 6, the feeding, treatment, and subsequent discharge of raw materials are carried out almost in the same way as shown in Fig. 5, but the updraft is introduced through two inlets 18 and 19. . The airflow from one inlet 18 is distributed and supplied by the perforated plate 20 to form a fluidized bed, and the airflow from the other inlet 19 is directly supplied into the apparatus body to form a spouted bed. The method in which powder and granular materials are processed using a mixed fluidized bed and spouted bed is called an improved spouted bed method.

The one shown in FIG. 7 is a multi-stage fluidized bed apparatus, in which powder and granular material supplied to the upper stage as indicated by arrow A is gradually treated at each stage.
Further, it moves to the lower stage through the overflow pipes 21, 21', 21''!l-, and is then discharged from the discharge port 22.

The rising air is supplied from the inlet 23 to the perforated plate 24 at each stage.
, 24', 24'', 24'',
After that, the structure is such that it is discharged from the discharge port 25.

In addition to the typical examples described above, fluidized bed devices with various structures have been proposed or put into practical use. Although these various fluidized bed devices have excellent heat transfer characteristics, they have low thermal efficiency and low reaction rate because they are complete mixing types, which are structural disadvantages. Therefore, in order to improve this problem, it is considered that the ideal form of a fluidized bed apparatus is to make the upward air flow and the flow of the powder particles countercurrent and to form a multi-stage fluidized bed.

Therefore, the present inventor conducted various research on devices that have been put into practical use and have only been proposed as the next device but have not been implemented, and found that in order to realize the above-mentioned ideal form, the air volume (amount of upward airflow) should not be changed. We focused on the fact that it is necessary to be able to easily increase or decrease the amount of granular material retained in the fluidized bed.

The results of that study will be explained below. In general, the biggest difficulty in multi-stage fluidized bed equipment is the mechanism that brings the powder and granules into countercurrent contact with an ascending air current, forming a fluidized bed at each stage and sending a fixed amount of the powder to the lower stage. . Furthermore, in a multi-stage fluidized bed apparatus using a perforated plate as the bottom plate of each stage of the fluidized bed as shown in FIG. 7, it is difficult to put it into practical use because a stable fluidized bed state is not exhibited except in a certain limited operating area. hand,
In reality, we are forced to abandon countercurrent flow and develop horizontal multi-nitriding.

On the other hand, the present inventor previously published Japanese Patent Publication No. 59-11334, 60
No. 22273 and No. 60-22274 proposed and put into practical use an empty tower type multistage jet (flow) device. This device does not use the above-mentioned perforated plate and has multiple stages of countercurrent flow, but it is also difficult to have more than two stages, so the temperature of the exhaust gas in the ascending air is still high, so the thermal efficiency is low. Unfortunately, efficient heat recovery is required.

Conventionally proposed methods for creating multiple stages of countercurrent flow include (a) using overflow pipes, and (b) using the bottom plate of the fluidized bed as a perforated plate and allowing particles to fall through the openings (holes) of the perforated plate.

In method (a), an overflow pipe (21 in Fig. 7) is installed between stages.
~21”), the falling amount of powder and granules is not constant,
There are methods such as inserting an orifice plate at the bottom of the overflow pipe, and installing a valve in the overflow pipe proportionally. However, even with this method, there are certain limitations in controlling the amount of powder and granules retained in each fluidized bed and preventing clogging of the overflow pipe by adjusting the supply rate of the powder and granules. Not easy to control. Generally, the amount of granular material retained in a fluidized bed is expressed by the following equation (1).

W = Δp-AT (1) W: Retention amount 0C9) Δp: Pressure loss (K
q/rr? ) AT: Cross-sectional area of a cylindrical vessel of a fluidized bed device (-) In the (-) or (mouth) method, in a steady state, the amount of granular material falling through the opening of the perforated plate is equal to the feeding rate of the granular material. However, it is known that the falling amount of each stage is proportional to the amount of powder particles retained and inversely proportional to the flow velocity of the upward air current.

FηW/u”・・・(2) F: Falling amount (Kg/5ee) W: Retention amount (Kp) U: Flow velocity (m/5ee) Therefore, the powder forming the fluidized bed is porous. The amount discharged from the plate openings varies depending on the flow velocity of the airflow blown up at the holes, so there is a drawback that the flow velocity range of the rising airflow to obtain a stable flow state corresponding to the amount of retention in each stage is narrow. .

For this reason, as a means to control the amount of stagnation in each stage, a separate outlet for circulating airflow is installed in the porous part of each bottom plate, and by controlling the amount of airflow, the flowing powder and granules are forced. A method has been proposed to drop the
-43644) 0 In the current technology, with countercurrent or multi-stage systems, the height of the overflow pipe and the amount of rising air must be adjusted to adjust the amount of retention in each stage. There are drawbacks. In particular, increasing or decreasing the amount of ascending air current may cause changes in temperature, atmosphere, and concentration during roasting or reaction, making operation control at each stage difficult.

Therefore, in order to realize the above-mentioned ideal form, it is necessary to control the retention amount and flow conditions of each stage by a method that does not involve an increase or decrease in the amount of rising air.

Elaborate Means to Solve the Problems This invention improves these drawbacks by providing a countercurrent multi-stage structure that allows the amount of granular material retained in each stage and the flow conditions to be adjusted even during operation without changing the amount of upward air flow. The object of the present invention is to provide a fluidized bed apparatus that is not seen in the prior art in that it is a fluidized bed apparatus, and even if the fluidized bed is in a single stage, it is extremely easy to adjust the retention amount and fluidization conditions.

In other words, in the above-mentioned method that does not use an overflow pipe, adjusting the amount of powder that falls from the porous portions of each stage is mainly related to the flow velocity of the updraft that blows up. (hereinafter referred to as gas amount) must be increased or decreased. This is because the area of the opening in the perforated plate is fixed. Therefore, we focused on the fact that the above problems should be solved if the fluidized bed apparatus had a structure in which the above-mentioned area could be changed during operation.

It is determined by An amount corresponding to the pressure loss (Δp) of the rising air flows floatingly, but if the raw material of powder or granules is continuously supplied, the balance of equation (1) above is lost, and the next amount is proportional to the supply amount, and the next amount is It will fall to be automatically pushed out.

According to such an opening drop method, there is no need to forcibly drop the discharge amount (change the gas amount) for each stage. In other words, if you can change the area of the opening (falling part) under a constant gas amount, the blow-up flow rate will change and the falling amount will change accordingly, so a new retention amount will be created under a constant raw material supply rate. It is formed. In other words, the following relationship holds true: change in opening area → change in blow-up flow rate → change in Δp → change in retention amount.

Even if we say that the opening area is changed here, in the fluidized bed apparatus using the above-mentioned perforated plate, the pores are uniformly distributed over the entire cross section, so the pores are changed during operation of the fluidized bed apparatus. The area cannot be changed.

Therefore, in the other invention, a structure was adopted in which openings for upward airflow were provided evenly along the line.

The structure and operation of the present invention will be explained below based on examples.

Embodiment FIGS. 1 and 2 are sectional views of a single-stage fluidized bed apparatus and a multi-stage fluidized bed apparatus in which the present invention is practiced.

In Figures 1 and 2, 1 is a vertical cylindrical vessel forming the main body of the fluidized bed apparatus, 2 is a supply port for raw material powder, 3 is a discharge port for powder and granules, and 4 and 4' are rising air flows. 5 is an airflow inlet, and 5 is an airflow outlet. Next 6, 6'.

6" is the bottom plate of the fluidized bed, 7.γ is the area adjustment device of the openings 8 and 8' for blowing up the upward airflow, and the opening 8
-8' are formed along the circumferential surface between the fluidized bed bottom plate 6-6'' and the inner circumferential wall of the cylindrical vessel 1.

The powder and granules supplied into the fluidized bed apparatus as indicated by arrow A form a fluidized bed and a spouted bed by upward air currents blown up at openings 8 to g'.

A fluidized bed generally refers to a layer in which particles are suspended in a relatively slow updraft, whereas a spouted bed is a layer in which particles are suspended in a fountain-like manner in a high-speed updraft. This refers to the case where a

In these embodiments, the upward velocity of the rising air at the openings 8 to 8# is more likely to be the condition for forming a spouted layer than the upward blowing from the openings (porous sections) of the conventional porous plate. Therefore, the suspended flow of particles easily becomes agitated and is effective in the above-mentioned treatments such as reaction, roasting, drying, and calcination. Further, at a position slightly above the openings 8 to 8#, the flow velocity becomes slow, providing conditions for forming a fluidized bed.

Next, in this example, the adjustment of the amount of particles retained in the fluidized bed and the spouted bed and the mechanism by which particles fall through the openings 8 to 8# will be explained.

FIG. 3 is a partially enlarged view of the fluidized bed bottom plate 6, area adjustment device 7, and opening 80 in FIGS. 1 and 2.

FIG. 4 is a sectional view taken along the line AA'. In this example,
The area adjusting device 7 (Figs. 1 to 3) is 6 as shown in Fig. 4.
It has area adjusting plates 7a to 7fi divided into two area adjusting plates 7a to 7fi, each of which is slidably attached to the wall of the cylindrical vessel 1 so as to be narrowed by the brim 1a so that it can be operated from the outside. ing. Note that the brim is kept airtight around the entire circumference by a gasket.

Even during operation of the fluidized bed device, the area adjusting devices 7a to 7f
If it is pushed into the cylindrical vessel 1, the cross-sectional area of the opening 8 will be narrowed accordingly, and if it is pulled out, it will be widened accordingly. Also the third
Reference numeral 9 in the figures and FIG. 4 is a member that fixes and supports the fluidized bed bottom plate 6.

The opening area of the uppermost opening r in Fig. 2 can be freely adjusted by installing the fluidized bed bottom plate 6# in the inverted conical cylindrical part and making the elevator lO'''C vertically movable as shown in the same figure. adjusted to.

Next, the amount of powder particles supported by the rising air flow in the opening 8 (including 8' and 8'' in Fig. 2) is stagnant according to the relationship explained in the above equation (1). The amount by which the powder or granular material falls has the relationship as explained in equation (2).

Therefore, if the area of the listening ports 8 to 8# is kept constant and the flow velocity of the airflow is kept constant (constant gas amount), the amount of powder particles retained will be the amount balanced by equation (1), and Continuation 1 I Hato n1 mackerel A4-I Rinha 1. Toshi 1-shii 匍凰yu慟 I shi, 1--48Δ continues to fall (balanced by equation (2)). Therefore, opening 8~ If the area of 8" is constant, the retention amount cannot be adjusted unless the gas amount is increased or decreased. However, according to this embodiment, even if the gas amount is kept constant, the area adjustment of the area adjustment device 7 is not possible. Plate 7a etc. or elevator 1
0 can adjust the area of the openings 8 to 8',
The flow velocity of the updraft in the openings 8 to 8' can be increased or decreased by the adjustment. According to the relationship between equations (1) and (2), if the flow velocity increases, the amount of falling water will decrease and the amount of retention will increase, while if the flow velocity will decrease, the amount of falling water will increase and the amount of retention will decrease. In either case, it corresponds to the flow velocity and is balanced by the subsequent retention amount and falling amount.

As described above, according to this embodiment, even if the gas amount is constant, the retention amount can be arbitrarily adjusted within a certain range, so it is easy to change the reaction temperature, time, and atmosphere conditions in the apparatus.

In addition, particles are blown up from the openings in the peripheral wall instead of being blown up over the entire cross section by the openings in the perforated plate as in the past, so particles are blown up into the jet layer; As a result, the particles as a whole are subjected to intense agitation due to the falling jet.

In Naoto's invention, the opening ratio of the opening along the peripheral wall (opening area per cross-sectional area of the cylindrical vessel at the opening) is set so that very good flow and jet conditions can be obtained with the desired retention amount. This varies depending on the particle size and gas amount, but experiments have shown that a range of 15 to 30 inches is preferred.

Next, in this invention, as shown in FIG. 2, the fluidized bed bottom plate is provided in multiple stages such as 6 to 6', and by providing openings corresponding to the number of stages and an area adjustment device for the openings, the powder and granule material can be A multi-stage fluidized bed device with countercurrent airflow can be used. With this, it is also possible to adjust the retention amount (time) of the powder or granular material at each stage to be different. With such a multi-stage structure, different purposes such as preheating (heat recovery), calcination, calcination, and cooling can be carried out in a single device at each stage, thereby increasing thermal efficiency and reaction rate. Furthermore, if the cylindrical vessel 1 of the fluidized bed apparatus is shaped so that its cross-sectional area differs in the vertical direction as shown in Fig. 2, the flow velocity of the airflow in each cross section can be varied, so that, for example, fine powder particles can be It is possible to reduce the proportion carried by the airflow from the outlet 5.

Next, in the multi-stage fluidized bed apparatus of the present invention, the supply ports for powder and granules are provided in multiple stages as necessary, so that powder and granules such as powder raw materials, oxidizers, reducing agents, solid fuel, etc. are supplied to each stage. It is also possible to supply them separately and perform various reaction treatments. Similarly, the air flow inlets can be provided in multiple stages, and air, gaseous fuel, redox gas, burner, etc. can be introduced separately at each stage. Naturally, the minimum requirement is that the powder supply port be provided above any of the openings, and that the airflow inlet be provided below any of the openings.

Furthermore, although the shape of the cylindrical vessel of the fluidized bed apparatus in this invention has mainly been described as a cylindrical shape, a rectangular cylindrical shape can also be used. If the bottom plate of the fluidized bed is formed into a conical or pyramidal shape in accordance with the shape of the above-mentioned cylindrical vessel, it can be made to conform to the formation of the above-mentioned doughnut-shaped surrounding wall spouted bed.

Effects of the Invention From the above, the following effects of the invention can be obtained.

(1) When the apparatus according to the present invention is used for firing powder and granules, heat is transferred from the rising air to the powder and granules as the stages are stacked, and heat can be recovered up to the desired temperature, so thermal efficiency is greatly improved. will be improved.

(2) When used as a reactor, the amount of retention in each stage can be arbitrarily selected, making it easy to control the reaction temperature and reaction time even during operation of the device. Also, if necessary, reducing agent,
The gas atmosphere can also be controlled by using an oxidizing agent.

(3) Since the reaction rate can be increased by realizing multi-stage countercurrent flow, the device can be made smaller.

(4) When used as a cooler, heat exchange from the powder to the air stream is efficiently performed by the reverse effect of (1).

(5) Compared to conventional fluidized bed devices, the aperture ratio is larger and the rear openings can be gathered together on the peripheral wall, so the pressure loss at the rear openings is also reduced.

(6) Since the opening area can be changed from the outside during operation,
Even if the particle size of the supplied particles changes or the particle size decreases due to reaction, it is possible to create appropriate flow conditions (gas amount, flow rate) corresponding to the change in particle size.

(7) By dividing the fluidized bed into multiple stages in the height direction, a good jet flow condition can be created at all times, so the problems of slagging and bubble generation, which are concerns with a single stage, can be greatly improved. .

(8) Since a spouted bed can be formed at each stage, intense flow occurs, and all the particles at each stage come into contact with high-speed upward air currents when falling, so that the heat transfer rate and reaction rate are further increased.

(9) Adjustment of the retention amount has a wide range of applications for increasing and decreasing processing capacity.

(10) It can be applied to a wide range of temperatures by using a fluidized bed bottom sheet metal material for low-temperature processing and a refractory material for high-temperature firing.

(U) Since the burner is not installed on any stage, each stage (1
2) If the area of the opening is adjusted appropriately, it can also be used as a catalytic reaction device using a fluidized catalyst.

[Brief explanation of drawings]

FIG. 1 is a side cross-sectional view of a single-stage fluidized bed apparatus which is an embodiment of the present invention, FIG. 2 is a side cross-sectional view of a multi-stage fluidized bed apparatus which is another embodiment of the present invention, and FIG. FIGS. 1 and 2 are partially enlarged views of the fluidized bed bottom plate 6, opening 8, and area adjustment device 70, FIG. 4 is a sectional view taken along the line A-N in FIG. 3, and FIGS. FIG. 3 is a diagram showing a typical example of a layer device. 1... Cylindrical vessel 2... Powder supply port 3...
・Powder discharge port 4,4... Air flow inlet 6~6"・
...Fluidized bed bottom plate γ...Opening area adjustment device 8~8"
...Opening procedure amendment document March 26, 1986

Claims (9)

[Claims] (1) In a fluidized bed device that is used by forming a fluidized bed and a spouted bed of updraft and powder in a vertical cylindrical container, the peripheral wall and the fluidized bed bottom plate are formed along the inner peripheral wall of the cylindrical container. An opening with a variable area structure is provided to blow up the rising air between the
A powder supply port is provided above the opening, a powder discharge port is provided below, an air flow inlet is provided below the opening, and an air flow discharge port is provided above. A peripheral wall spouted fluidized bed device characterized by: (2) Claim 1, characterized in that a plurality of openings with a variable area structure are provided in the vertical direction within the cylindrical container.
The peripheral wall spouted fluidized bed apparatus described in . (3) The peripheral wall spouted fluidized bed apparatus according to claim 1 or 2, characterized in that the cylindrical vessel has a shape whose cross-sectional area differs in the vertical direction of the cylindrical vessel. (4) A variable area structure in which the area of the opening is changed by inserting and removing an area adjusting member from the outside of the cylindrical vessel into the opening formed between the fluidized bed bottom plate and the inner peripheral wall of the cylindrical vessel. A peripheral wall spouted fluidized bed device according to claim 1 or 2, characterized in that it has: (5) It has a variable area structure in which the area of the opening formed between the fluidized bed bottom plate and the inner circumferential wall of the inverted cone-shaped cylindrical vessel is changed by moving the fluidized bed bottom plate up and down. A peripheral spouted fluidized bed apparatus according to claim 1 or 2, characterized in that: (6) The peripheral wall spouted fluidized bed device according to any one of claims 1 to 3, characterized in that a plurality of powder supply ports are provided in the vertical direction of the cylindrical container. (7) The peripheral wall spouted fluidized bed device according to any one of claims 1 to 3, characterized in that a plurality of air flow inlets are provided in the vertical direction of the cylindrical vessel. (8) The peripheral wall spouted fluidized bed device according to any one of claims 1, 2, 3, 6, or 7, characterized in that the shape of the cylindrical container is cylindrical or prismatic. (9) The peripheral wall jet type fluidized bed apparatus according to claim 1, wherein the fluidized bed bottom plate has a conical shape.