JP2534502B2 - Circulation rate control method for high temperature powder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for controlling the circulation rate of hot particles in a fluidized bed involving circulation of particles.

[Conventional technology]

As a method of controlling the particle circulation speed of the circulating fluidized bed,
A valve such as a ball valve is directly installed to control the opening of the valve well, a fluidized bed type overflow method called a pneumatic valve, and a nozzle port and a pumping outlet for pumping air (fluidizing gas) A method in which the distance Δh to the opening at the lower end of the pipe can be changed, and the circulation speed is changed by changing the distance Δh (Japanese Patent Publication No. 58-33).
450) etc.

[Problems to be solved by the invention]

Among the above-mentioned conventional techniques, the method of controlling by the valve opening degree is easy to apply in the case of particles at room temperature or relatively low temperature, but at a high temperature, for example 500 ° C It will be difficult. Further, the method of controlling by changing the distance of the pneumatic valve or the nozzle has a complicated structure or has a movable part, and is therefore not suitable for a small device in particular.

The present invention provides a method for controlling the circulation rate of hot particles in a circulating fluidized bed, which has a simple structure and has no moving parts, and can be used for both small and large equipment.

[Means for solving problems]

The present invention supplies the main fluidizing gas from the position where the fluidized bed and the inclined pipe meet, that is, the same plane as the horizontal plane including the upper end of the opening to the fluidized bed main body or a position above the horizontal plane. It is characterized by controlling the particle circulation speed by changing the amount of auxiliary gas flowing from the lower part to the inside of the fluidized bed and to the inclined tube. Compared with the conventional method, the structure is very simple, there are no moving parts, and durability is also No problem.

And since the present invention causes the main fluidized gas to flow from the same plane as the horizontal plane including the upper end of the opening to the fluidized bed main body or from a position above the horizontal plane, it is independent of changes in the gas amount of the fluidized gas. Since the particle circulation speed can be controlled and the fluidizing gas hardly flows into the inclined pipe, and hence the upright pipe that follows it, the reaction gas is made to flow as the main fluidizing gas, and the inert gas is supplied to the inclined pipe for controlling the circulation speed. If it is made to flow, there is no problem that the circulating particles are melted or sinter in the inclined pipe and the upright pipe. Then, it is possible to control the circulation speed by changing the gas amount of both or one of the gas blown to the bottom of the merging portion and the gas blown to the inclined pipe near the merging portion on the fluidized bed body side. It is preferable that the amount of gas flowing into the lowermost body side layer of the merging portion is kept constant and the amount of gas flowing into the inclined pipe near the merging portion is changed. This method can control the particle circulation rate over a wide range with a small amount of gas.

In that case, what is used to directly control the particle circulation velocity is the amount of gas flowing to the auxiliary gas outlet in the vicinity of the opening of the inclined tube. , The upward gas superficial velocity is the minimum fluidization velocity (below
It is also important to flow a fixed amount of auxiliary gas that is 3 times or less, preferably 2 times or less than Umf). If it exceeds 3 times Umf, the fluidization in this part becomes vigorous, so that the circulation amount increases, but it becomes difficult to uniquely control the circulation amount by the gas amount fed into the inclined pipe. If it is less than 1 time of Umf, pulsation is likely to occur. Therefore Uf / Umf in this part is
It is preferably 0.8 or more. This amount of gas makes it possible to smooth the movement of particles at the confluent portion and to perform stable particle circulation. Then, by changing the amount of gas fed into the vicinity of the confluence of the inclined tube and the fluidized bed body in the range of zero to three times Umf or less as the superficial linear velocity with reference to the cross-sectional area of the inclined tube, The particle circulation velocity can be linearly controlled as shown in FIG. In this case, the increase in the circulation amount will reach the ceiling even if the gas amount that exceeds three times Umf is fed. A part of this gas flows upward in the inclined pipe, and the rest flows into the opening with the fluidized bed. This gas inlet (1st
The position of FIG. 8) is relatively arbitrary, but it can be said that a position at a distance of about twice the pipe diameter in the axial direction when viewed from the inclined pipe opening is a preferable position.

On the other hand, when the amount of gas blown into the inclined pipe is specified as Up = Uf / Umf and fixed within the range of 0.3 to 3, the circulation amount can be controlled by increasing or decreasing the amount of gas blown into the lower part of the fluidized bed body. found. FIG. 4 is a diagram showing the relationship between the amount of gas blown into the lower part of the fluidized bed body and the particle circulation speed when the amount of gas blown into the inclined tube is parameterized. After all, the particle circulation amount can be controlled by changing the two auxiliary gas amounts when the blowing amount of the high temperature gas is constant, and the selection can be freely made within a certain limit.

As described above, the present invention provides a method capable of performing stable circulation of high-temperature particles in a circulating fluidized bed and easily controlling the particle circulation speed, though it has no moving parts and has a very simple structure. Is.

 The invention will be further explained with reference to the drawings.

FIG. 1 shows a method of controlling the circulation speed of high temperature particles in a high temperature circulating fluidized bed.

In FIG. 1, a high temperature reaction gas is introduced into a fluidized bed (riser) 1 through a main fluidizing gas outlet 6 to form a turbulent fluidized bed. The high-temperature particles supplied from the feed port 9 are sent from the fluidized bed to the sedimentation chamber 2 by gas, separated from the gas, and then return to the lower part of the fluidized bed 1 through the upright pipe (downcomer) 3 and the inclined pipe 5. Particles that could not be completely separated in the sedimentation chamber 2 are further separated by the cyclone 4,
It is returned to the upright pipe 3 and discharged from the reaction product outlet 10.

A certain amount of auxiliary gas is introduced from the gas outlet 7 at the bottom of the fluidized bed and a variable flow rate of auxiliary gas is introduced from the gas outlet 8 near the confluence of the inclined tube to control the particle circulation speed.

〔Example〕

Example 1 A fluidized bed of 40 A (inner diameter 38.4 mm), a height of 3 m,
The downcomer and inclined pipe are 65A (inner diameter 70.3mm), and the circulating fluidized bed as shown in Fig. 1 with the inclination angle of 60 ° is used.
p = 0.2mm, ρs = 4300Kg / m ³ : Umf = 0.022m / s, Ut = 2.04
m / s) at a temperature of 900 ° C and a superficial gas linear velocity of the fluidized bed of 6.
In the case of 9 m / s (3.4 times Ut), the amount of gas from the bottom of the fluidized bed was set to 84 Nl / H (1.2 times Umf) using the present invention, and it was placed at a position about 15 cm from the lower end of the opening. The amount of gas in the inclined tube from the gas outlet with an inner diameter of 16.7 mm is 35, 58, 85, 120 Nl / H.
(0.5, 0.83, 1.2, 1.7 times of Umf, respectively). As a result, the circulation speed of the fine ore based on the fluidized bed cross section is
It became 65, 125, 195, 295 Kg / m ² / s.

Here, Ut: terminal velocity, p: average particle size, ρs: true density of particles.

Example 2 Using the same apparatus as in Example 1, α-alumina particles (
p = 0.21 mm, ρs = 3970 Kg / m ³ ; Umf = 0.02 m / s, Ut = 2.05
m / s) at a temperature of 900 ° C and a superficial gas velocity in the fluidized bed of 6.
In the case of 9 m / s (3.4 times Ut), the present invention was used, the gas amount from the bottom of the fluidized bed was kept constant at 71 Nl / H (1 time Umf), and the gas amount to the inclined tube was 30, 52, 72, 107, 145 Nl / H (each
Umf 0.42, 0.72, 1.0, 1.5, 2.0 times). As a result, the circulation speed of α-alumina particles based on the fluidized bed cross-sectional area was 40, 62, 95, 135, 200 Kg / m ² · s.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY The present invention is a method for controlling the circulation speed of high-temperature powder or granules in a circulating fluidized bed, because there is no mechanical element, durability is not a problem, and high-temperature powder or granules are stable despite the simple structure. Since it can be circulated and the circulation speed can be surely controlled immediately, it is extremely effective in practice.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, and FIG. 2 shows an enlarged detail of a main part thereof. Figure 3 shows Uf / Umf on the main body side at the position of the lower end of the opening of the inclined tube to the main body of the fluidized bed.
Fig. 12 is a graph showing the relationship between the amount of gas fed into the inclined tube with Ur as a parameter and the circulation amount of particles (the arrow shows that Uf / Umf = Ur in the body in Fig. 2 surface is a parameter). ). FIG. 4 is a graph showing the relationship between the main body side auxiliary gas amount and the particle circulation amount with Uf / Umf = Up on the inclined pipe side as a parameter (the arrow indicates the inclined pipe axis of the gas amount blown out from FIG. 3). Uf / Umf = Up in the direction is shown as a parameter). 1 ... Fluidized bed (riser), 2 ... Settling chamber 3 ... Upright pipe (downcomer) 4 ... Cyclone, 5 ... Inclined pipe 6 ... Main fluidized gas outlet 7 ... Fluidized bed bottom auxiliary Gas outlet 8 …… Inclined tube auxiliary gas outlet 9 …… Feed port, 10 …… Reactant outlet 11 …… Upper end of inclined tube 12 …… Lower end of inclined tube

Front Page Continuation (72) Inventor Teruhiko Hirabayashi 1-17-25 Kasuya, Setagaya-ku, Tokyo (72) Kazuya Kunitomo 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Shin-Nippon Steel Research Laboratories No. 1 ( 72) Inventor Yoichi Hayashi 1-1-1 Emitsu, Hachimanto-ku, Kitakyushu City, Fukuoka Prefecture (3) Technical Research Laboratory, Nippon Steel Corporation (56) Reference JP-A-52-129683 (JP, A) -189330 (JP, U)

Claims (1)

(57) [Claims] 1. A circulating fluidized bed in which high-temperature particles return from the fluidized bed to a lower part of the fluidized bed through a sedimentation chamber, a particle separator such as a cyclone, an upright pipe, an inclined pipe, etc. The inclined pipes are merged and opened with the above inclination, and the main fluidizing gas is supplied to the fluidized-bed body from the same horizontal plane as the upper end where the inclined pipes open, or from above the same horizontal plane. Auxiliary gas is supplied from the lowermost part of the fluidized bed so that the superficial linear velocity is 3 times or less than the minimum fluidization velocity in the lower part, while the amount of calculation of the axial superficial linear velocity in the inclined tube is near the opening. Is supplied at a rate of 3 times or less than the minimum fluidization rate, and the circulation rate of hot particles is controlled by changing at least one of the amounts of these two auxiliary gases.