JPH073316A - Particle discharging method and apparatus for fluidized bed reactor - Google Patents

Abstract

PURPOSE:To provide the method and device in which a grain from a fluidized- bed reactor is stably discharged. CONSTITUTION:A moving packed bed 8 of grains is bent in the shape of a U in the grain discharge device of a fluidized-bed reactor. The packed bed 8 on the reactor side of the bent part 13 has a length sufficient to seal the reactor pressure by the pressure drop of the packed bed, and the discharge of the grain is controlled by adjusting the supply of a carrier gas from the bottom of the bent part 13 of the packed bed 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for discharging particles in a fluidized bed reactor and an apparatus for carrying out the method.

[0002]

2. Description of the Related Art As an alternative to the conventional hot metal production technology using a blast furnace, attention has been paid to a smelting reduction method for producing hot metal inexpensively by using powdered ore, steam coal, omitting a coke process, and the like. Exhaust gas generated by this smelting reduction method,
The reducing power and the retained heat are effectively used by supplying it as a fluidizing gas in a fluidized bed reduction furnace for the preliminary reduction of the raw ore.

As such a fluidized bed reduction furnace, a powdered ore charging section is provided on the side, a carrier gas introducing section for forming a fluidized bed is provided near the bottom, and a fluidizing gas introducing section in which a nozzle is provided on the entire bottom plate of the fluidized bed. A riser forming a fluidized bed provided with
A downcomer having a powder flow part for circulating powder through a cyclone on the outside thereof.
There are a type disclosed in No. 11807 and a non-circulation type fluidized bed that does not return powdery iron ore (reduced ore) collected by a cyclone to the riser.

In any of the types, as a device for discharging a reduction ore as a product, since the gas pressure in the fluidized bed in the riser is high, a rotary feeder, which prevents harmful gas containing CO from leaking in the furnace, Mechanical ones such as screw feeders and those with high sealing properties such as gas-conveying pneumatic feeders are used.

However, among the conventional reduced ore discharging devices of the fluidized bed reduction furnace, the discharging device by mechanical means such as a rotary feeder and a screw feeder has a high internal temperature of the fluidized bed reduction furnace of 900 to 1000 ° C. In addition, since the ore is cut out in a reducing gas atmosphere in which a corrosive gas such as H ₂ O or SO ₂ is rich, rotating parts due to high temperature corrosion of the constituent materials, deterioration due to stress corrosion and mechanical wear. Many troubles occur. The reducing gas is CO,
It contains tens of percent of H ₂ harmful gas, and if it leaks to the outside of the system, there is a great risk of causing a serious human or physical disaster due to explosion or poisoning. Therefore, a structure is adopted in which the gap between the blade tip of the rotary blade and the casing is reduced to prevent gas leakage. However, when the high temperature powdered ore is cut out, the seal portion of the blade edge is immediately worn to cause a gas leak, or the gap between the blade edges is small, so that the powder particles are caught and the rotation is stopped. For this reason,
The operability was very poor and the maintenance cost was very high.

On the other hand, in the case of a gas-conveying type discharging device using a carrier gas such as a pneumatic feeder, since there is no rotating member for cutting out, it is excellent without the above problems. Can be said.

However, in the case of this pneumatic feeder, when the pressure difference between the pressure in the fluidized bed and the outside air pressure is large, the pressure in the fluidized bed is totally affected by the pressure fluctuation in the fluidized bed. When the temperature rises, the iron ore in the powder seal portion of the pneumatic feeder is discharged to the outside air at once, so that the gas in the bed protrudes from the discharge port, making it impossible to control cutting. Once the powder seal part of the pneumatic feeder is broken, particles are carried by the gas stream in that part, so it is difficult for the particles to collect, and the powder seal mechanism does not easily recover, which makes stable operation impossible. There is.

[0008]

The problems to be solved in the present invention include wear troubles of a mechanical discharge device in a reactor of a powdery granular material by a fluidized bed, and powder seal when a pressure in a furnace of a gas transfer type discharge device rises. The object is to find a means that enables stable discharge of particles by eliminating defects of the particle discharge device such as collapse trouble.

[0009]

According to the method for discharging particles of a fluidized bed reactor of the present invention, a U-shaped packed moving bed is formed below the main body of the fluidized bed reactor, and the U-shaped packed moving bed is formed. The length of the portion located on the furnace body side is set to a length at which the pressure inside the furnace can be sealed by the pressure loss of the packed bed, and a carrier gas is introduced from the bottom of the U-shaped packed moving bed, and the introduced gas amount It is characterized in that the particle emission amount is controlled by adjusting.

As a device for carrying out the method for discharging particles in the above fluidized bed reactor, a vertical downcomer connected to the bottom of the furnace body and an inclined descent provided at an appropriate angle with respect to the subsequent horizontal plane. A pipe and an ascending pipe having a particle discharge port at one end are connected continuously to form a substantially U-shaped continuous pipe, and a plurality of carrier gas inlets and a control device for the gas are provided in the continuous pipe. In addition to being provided, a device can be used in which the sum (L) of the lengths of the vertical downcomer and the inclined downcomer is set by the following equation.

L = a × ΔP × dp ² / (Ug × μg) In the above equation, a: coefficient ΔP: pressure difference between furnace and outside air (mm / Aq) dp: average particle diameter of reduced ore (m) Ug; leak gas flow rate (m / s) μg from inside the furnace flowing between the reduced ore particles in the packed moving bed; viscous coefficient of leak gas.

[0012]

Since the gas inside the furnace is sealed by an appropriate pressure loss of the curved packed moving bed formed in a U shape, and the particles forming the packed moving bed on the fluidized bed reactor side are operated within a range that does not fluctuate,
Even if the internal pressure of the furnace fluctuates a little, the powder seal does not collapse due to the filling movement.

Further, since the fluidized bed reactor side of the U-shaped curved packed moving bed is formed by an inclined downcomer, the mobility of particles is improved, particles are discharged smoothly, and a large amount of particles are cut off. The output is improved.

[0014]

EXAMPLE FIG. 1 shows an outline of a fluidized bed reduction furnace to which the present invention is applied.

In the figure, the raw material supplied from the raw material ore supply port 1 into the riser 2 forms a fluidized bed 4 by the reducing gas introduced from the gas introduction port 3 at the bottom, and a reduction reaction is carried out. Reference numeral 5 denotes a granular circulation system, which is composed of a cyclone 6 for collecting the powdery matter discharged from the top of the riser 2 and a downcomer 7 following the cyclone 6, and a packed moving bed 8 formed below the downcomer 7 is It is continuously circulated downward in the riser 2.

Reference numeral 9 denotes a device for discharging particles (reduced ore) formed at the bottom of the riser 2. The discharge device 9 has a vertical downcomer pipe 10 continuous to the bottom of the riser 2, a slanting downcomer pipe 11 following the riser pipe 12, and a riser pipe 12 having a discharge port 17 at one end, which are connected in a substantially U-shape. A curved moving filling layer 13 is formed. At that time, the inclined downcomer 11
In order to improve the mobility of the particles, is provided at an angle θ with respect to the horizontal plane, for example, an angle of repose or more (about 60 ° in this embodiment). Carrier gas introducing portions 14, 15 and 16 are provided on the bottom surface, the side surface of the vertical downcomer pipe 10 and the lower surface of the inclined downcomer pipe 11, respectively. By adjusting the amount of carrier gas blown from each introducing portion, The particle moving speed of the packed moving bed 13 is controlled, and the reduced ore is discharged from the rising pipe 12. In this reduction ore discharging device, U
The sealing pressure of the packed moving bed formed in a letter shape is determined by the leak gas flow rate from the furnace flowing between the reduced ore particles forming the packed moving bed and the packed moving bed length (packed bed pressure loss). Pressure difference ΔP (mmAg) between the inside of the furnace and the outside air, average particle diameter dp (m) of the reduced ore, leak gas flow rate Ug (m / m) flowing between the reduced ore particles in the filling transfer furnace
s), the leak gas viscosity coefficient μg (kgs / m ² ), and the particle shape correction coefficient a (−), the length L (m) of the packed moving layer required for the pressure seal is L = a × ΔP
× dp ² / (ug × μg) can be expressed as (1). Here, L is the length of the packed moving bed formed in the vertical downcomer and the inclined downcomer, and a is a coefficient obtained experimentally. Pressure difference between furnace and outside air 1500-max 200
0 mmAq, temperature 900 ° C., average particle size 155 μm (a
= 0.00013) applied to a reduction ore discharge device of a fluidized bed reduction furnace for reducing powdered ore, and the allowable leakage amount of gas in the furnace is 0.01 / mm ³ or less, the pressure seal of the moving packed bed The length was 2 m (vertical downcomer: 1.5 m, inclined downcomer: 0.5 m, pipe vertical: 0.1 m). As a result, it is possible to form a powder seal mechanism that is sufficient with respect to fluctuations in the furnace pressure. During operation, downcomer 1
Filling moving bed formed in the downcomers 10 and 11 by injecting carrier gas into the side walls of 0 and 11 and adjusting the amount of carrier gas to be less than or equal to the fluidization start speed (amount) of the reduced ore. The reduced ore is discharged to the outside of the furnace by using the particle's own weight and the pushing force by the pressure in the furnace. The blown carrier gas relaxes the particle pressing force of the reduced ore against the side wall surface, and the wall frictional force that restrains the reduced ore from descending is reduced. ，
11 is descended and pushed out of the ascending pipe 12. The rate of discharge of the reduced ore is proportional to the amount of carrier gas blown from the carrier gas introduction parts 14, 15, 16. Further, since the rising speed of the carrier gas blown from the carrier gas introduction parts 14 and 15 in the downcomers 10 and 11 is adjusted to be equal to or lower than the fluidization start speed of the reduced ores, the fluidization of the reduced ores in the downcomers 10 and 11 is performed. There is no reduction ore outflow and powder seal collapse due to.

[0017]

According to the present invention, the following effects can be obtained.

(1) Since there is no rotating member in the discharging device itself, troubles due to wear and corrosion do not occur in the discharging device itself.

(2) The amount of gas in the fluidized bed reaction furnace leaking out of the furnace is small, and the safety of the entire apparatus is high.

(3) Since particle emission control becomes smooth,
Stable operation of the entire equipment becomes possible.

[Brief description of drawings]

FIG. 1 shows an outline of a fluidized bed reduction furnace to which the present invention is applied.

[Explanation of symbols]

 1 Raw material ore supply port 2 Riser 3 Gas inlet port 4 Fluidized bed 5 Granule circulation system 6 Cyclone 7 Downcomer 8 Packing moving bed 9 Reduced ore discharge device 10 Vertical downcomer pipe 11 Inclined downcomer pipe 12 Ascending pipe 13 Curved in U shape Packed moving bed 14, 15, 16 Carrier gas inlet 17 Outlet

Claims (2)

[Claims] 1. A U-shaped packed moving bed is formed below a fluidized bed reactor main body, and the length of a portion of the U-shaped packed moving bed located on the furnace body side is adjusted by a packed bed pressure loss in the furnace. A method for discharging particles in a fluidized bed reactor, which has a length capable of sealing pressure, introduces a carrier gas from the bottom of the U-shaped packed moving bed, and controls the quantity of introduced gas to control the quantity of discharged particles. 2. A vertical downcomer connected to the bottom of the furnace body, an inclined downcomer following the vertical downcomer at an appropriate angle with respect to the horizontal plane, and an upcomer having a particle discharge port at one end, which are continuous with each other. To form a substantially U-shaped continuous pipe, which is provided with a plurality of carrier gas inlets and a control device for the gas, and which is the sum of the lengths of the vertical downcomer and the inclined downcomer. A particle discharging device for a fluidized bed reactor, wherein (L) is set by the following equation. L = a × ΔP × dp ² / (Ug × μg) In the equation, a; coefficient ΔP; pressure difference between the furnace and the outside air (mm / Aq) dp; average particle diameter of reduced ore (m) Ug; filling Leak gas flow velocity (m / s) μg from inside the furnace flowing between reduced ore particles in the moving bed; viscosity coefficient of leak gas is shown.