JPH0311203A - Solid particle supply device for fluidized bed - Google Patents

Abstract

PURPOSE:To sharply reduce the number of supply nozzles by providing a specific flow control element in an ambient space apart by a given distance from a supply nozzle mounting position in the fluidized bed of solid particles pneumatically conveyed by the carrying air. CONSTITUTION:A flow control element 2 which has a void smaller than that of the whole fluidized bed 1 and introduces a fluid and the air from a bottom opening 6 to blow out them from an upper opening 7 is arranged in the neighborhood of a supply nozzle 4 for supplying such a solid particle as a coal particle into the fluidized bed 1. The flow control element 2 has the void larger than that of the whole fluidized bed 1 and an inequality AN/AC<=1 holds where AN is the area of the upper opening 7 and AC the area of the bottom opening 6. The upper opening 7 is opened only in a direction wherein the solid particles supplied into the fluidized bed 1 are desired to be diffused. This construction accelerates the fluid and the air introduced in the flow control element 2 and the fluid and the air blown out in a direction wherein a solid fuel is desired to be diffused as a powder jet stream with a higher speed by far than that in the bed whereby the solid fuel blown out from the supply nozzle is diffused.

Description

Detailed Description of the Invention (Industrial Application Field) This invention involves introducing a fluid from below a bed filled with solid particles called a fluidizing medium, and suspending the fluidic medium in a state in which the fluidic medium is suspended by the flow of the fluid. The present invention relates to a solid particle supply device for a fluidized bed that uniformly disperses and supplies solid particles to a fluidized bed.

(Prior Art) When a fluid is supplied from the bottom of a container filled with powder consisting of a large number of particles, the powder layer changes from a fixed bed to a fluidized state at a certain fluid velocity or higher.

This phenomenon is widely known as a fluidized bed, and is used in many industrial devices such as coal-fired fluidized bed boilers and waste incinerators as an extremely efficient method of contacting particles and fluids.

As shown in Fig. 8, a fluidized bed boiler has a combustion chamber 101 called a fluidized bed, and a fluidized bed 101 has a bed structure.
A fluidized bed is constructed of sand and limestone (CaCO3) called 02, and air is sent through air holes called a dispersion plate 103 to fluidize the fluidized medium 102 and coal particles with a diameter of 10,111 m or less (4 to 6 cities) are formed. The coal was made to burn naturally by adding

The steam pipe 104 that generates steam is connected to the fluidized medium 102.
It is designed to be installed inside the tank to directly absorb combustion energy. In this fluidized bed boiler, coal particles are supplied into the fluidized bed 101 by conveying air through a large number of coal feed pipes 105. The coal feed pipe 105 has a coal feed nozzle 106 as shown in FIGS. 7(A) or B) that ejects coal particles in a horizontal direction; We are trying to provide a diffused supply. In order to uniformly disperse solid particles and coal particles in the fluidized bed 101, currently the furnace bed area is approximately 1
One coal feeding nozzle 106 is arranged per d.

Therefore, if the furnace Mm volume is approximately 100, approximately 100
A coal feed nozzle is located here.

(Problems to be Solved by the Invention) However, in recent years, consideration has been given to improving efficiency by increasing the size of furnaces. For example, if a fluidized bed combustion furnace is designed with a furnace bed area of 500 bays, which is five times that of a conventional one, According to the conventional solid combustion feeding device, approximately 500 coal feeding nozzles are required. However, this coal feed pipe especially the elbow portion 107
There is a problem in that maintenance and management becomes difficult when there are as many as 500 pipes because they are rapidly eroded by solid particles (coal and limestone) being transported. This also applies when solid particles other than coal, such as solid particles with a low combustible content such as dry heat sludge, are diffused and supplied to the fluidized bed. Therefore, it is desired to reduce the number of coal feeding pipes as much as possible without deteriorating the diffusibility of solid fuel into the fluidized bed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a solid particle supply device for a fluidized bed that can significantly reduce the number of supply nozzles that diffuse and supply solid particles into a fluidized bed compared to conventional devices.

(Means for Solving the Problems) In order to achieve the above object, the present inventor conducted various studies on the flow conditions in the fluidized bed, and found that by forming a non-flowing part surrounded by solid walls in the fluidized bed, It has been found that it is possible to generate a powder jet at an arbitrary position and in an arbitrary direction at a much higher speed than the intrabed superficial velocity.

That is, in the fluidized bed, a non-flowing part is surrounded by a solid wall, and its cross-sectional area is Ac at the bottom z1, and the cross-sectional area A is smaller than or equal to Ac at the top Z2. , the internal pressure is isolated from the surrounding fluid part pressure by the solid surface, so the pressure balance follows Bernoulli's theorem. In Figure 0, which shows the definition diagram for the symbols, P1 is the outside pressure near the inlet of the non-flowing part surrounded by a solid wall, P2 is the outside pressure near the exit of the non-flowing part, and εP is the outside pressure near the exit of the non-flowing part. That is, the void ratio of the entire fluidized bed (fluidized bed) formed by the fluid 4a body in a fluidized state, ε. is the porosity of the non-flowing part, U is the velocity of fluid flow in the flowing part, Uc is the fluid velocity in the non-flowing part, Uo
is the ejection velocity of the fluid near the exit of the non-flowing part, and AT is the cross-sectional area of the entire fluidized bed.

The conservation of the total pressure of the fluid passing through the non-flowing section at the heights Zl and Zt is expressed as follows.

P1mo (ρF/2>UP = pc + (ρ, /2) UC2+ΔPc (Uc)■
pc+(ρ,/2)UC2 =p2+(ρF/2) UN 2+ΔPs(UN)■
Here, ρr is the fluidized fluid density.

However, when passing through a fixed layer (non-flowing area surrounded by solid walls),
and the pressure loss at the throttle part are Δpc(uc)=ζc(ρp/2) UC/
Ps(Us)=ζN(ρF/2)U.

ζc = 3.5 (1-e.) Lc / φe
dp (εC)′ζN ;ζN(Ac/AN) Here, ζN is the pressure loss coefficient.

The continuity formula and the area size relationship are respectively (JcAc=UN An A　＞　A　c＞　A　s becomes.

From the above, the ejection velocity U from the outlet of the constriction part of the non-flowing part whose surroundings are isolated from the pressure in the fluidized bed by a solid wall etc.
N is expressed by the following formula.

...■ Regarding the relationship between U and Lc, A N/A c and ε. The calculation results are shown in FIG. 5 using the following parameters.

g = 9.8re/S' ε, = 0.1
ρp =1540Kg/ra'ζ, =0.64
g/n'd for ε,,=0.4 ρ,=1.29
, =0.0010411φ, =1.0
UP =0.7rt/s From this relationship, A M/
When the value of Ac is large, Ul is high. It can be seen that the influence of LC increases as the value of A and /Ac decreases, although it does not change much. Mana ε. The larger the value, the higher the speed.

Therefore, in the solid particle supply device for a fluidized bed of the present invention, the solid particles, which are pneumatically transported by conveying air, are placed in a surrounding space a certain distance away from the supply nozzle installation position in the fluidized bed. also has a large porosity, and the ratio of the bottom opening area Ac to the top opening area AN is A M /
A flow control element is installed that satisfies the relationship A c≦1 and has an upper opening facing in the direction in which the conveyed solid particles are desired to be diffused.

(Function) Therefore, by means of a flow control element that forms a non-flowing part surrounded by solid walls in a fluidized bed, the superficial velocity within the bed is adjusted to the surrounding space a certain distance away from the installation position of the supply nozzle that ejects solid particles. A jet of powder with a much higher speed is generated in the direction of the desired diffusion, attracting the solid particles supplied into the layer from the supply nozzle, and quickly dispersing them in the direction of the desired diffusion.

(Embodiment S) Hereinafter, the configuration of the present invention will be described in detail based on an embodiment shown in the drawings.

FIG. 1 schematically shows an embodiment in which the solid particle supply device for a fluidized bed according to the present invention is applied to a coal feed device for a fluidized bed boiler. The coal device contains solid particles such as coal particles in the fluidized bed 1.
A space ratio ε smaller than the space ratio ε2 of the entire fluidized bed 1 is located near the supply nozzle 4, which is called a coal supply nozzle that supplies coal 1. A flow control element 2 is arranged to introduce fluid and air from a bottom opening 6 and eject it from a lower part between the upper parts.

In the figure, reference numeral 3 is a dispersion plate, 5 is a coal feed pipe, and 10 is a wind box that also serves as a flow generator and supplies combustion air.

The flow control element 2 has a void ratio ε larger than the void ratio ε of the entire fluidized bed 1. and the ratio of the bottom opening area Ac to the top opening area AN is in the relationship AN/Ac≦16 For example, as shown in FIG. 2 (A>), the overall shape is cylindrical, and the side wall A lower inter-upper part having a smaller diameter than the bottom opening 6 is provided at the upper part.

Furthermore, although not shown, the bottom opening 6 and the upper lower part may be formed equally, and the upper part lower part is opened in the direction in which it is desired to diffuse the solid particles supplied into the fluidized bed 1. For example, as shown in Figure 2 (A) and its cross-sectional view, Figure 2 (C), horizontally and radially, or horizontally as shown in Figure 2 (B). The opening is slightly upward or slightly downward from the horizontal (not shown). Of course, the upper inter-upper lowers are not limited to the case where they are arranged in two or three spread out in the radial direction, but one or more upper inter-upper lowers may be arranged, and all the upper inter-upper lowers are arranged at the same angle with respect to the horizontal plane. There is no need to do anything.

This flow control element 2 is arranged in a surrounding space a certain distance away from the installation position of the coal feed nozzle 4, preferably on or near the injection axis of the coal feed nozzle 4, and most preferably induced by the jet flow of the flow control element 2. The effect is the diffusion phenomenon of solid particles supplied (
1) is installed at a position as far away from the coal feeding nozzle 4 as possible within the range where it can occur effectively.
For example, Fig. 6 (C) shows an example of the arrangement combination when supplying from four directions.
As shown in FIG. do. In addition, the injection direction of the coal feed nozzle 4 and the direction of the lower part of the flow control element 2 are not necessarily made to coincide with each other, and the coal particles 11 ejected from the coal feed nozzle 4 are arranged in a direction that further spreads the particles more widely. In addition, the installation height of the flow control element 2 is the same as that of the coal feed nozzle 4, or is installed at a height that takes into account the influence of flow, for example, within about twice the height H of the coal feed nozzle. The number of flow control elements 2 to be installed is not limited, and the number of flow control elements 2 is preferably arranged as necessary. Fluidized bed 1
The attachment is carried out by fixing using a stay 12, for example. The ratio between the cross-sectional area of the fluidized bed 1 and the bottom cross-sectional area of the flow control element 2 is not particularly limited, but it is preferably sufficiently small compared to the fluidized bed area. For example, in this example, the cross-sectional area is 60 d. In a fluidized bed of about 1, the diameter is 30 to 40 cm and the height is 50 to 1
A large number of flow control elements 2 with a diameter of 0.00 mm are arranged. The flow ON control element 2 is made of a material that does not react with or have no adverse effect on the fluid medium or the fluid blown into the flow I-, and is preferably made of ceramics, for example.

Furthermore, in this embodiment, a net 8 is provided in the bottom opening 6 of the flow control element 2 in order to increase the void ratio εC. this#! 8 prevents particles from entering the element, and the void ratio ε. It is designed to maintain a large amount of Here, the porosity is the volume of the container minus the volume of particles divided by the volume of the container.The closer it gets to 1, the empty the container becomes, and the closer it gets to 0°, the more the container fills with particles. It will be exhausted.

The bottom opening 6 of the flow control element 2 is appropriately determined in relation to the fluid medium (particles). For example, when the particle diameter is 1 φ, the bottom opening 6 is set to be larger than Loanφ. As shown in FIG. 5, the relationship between the height of the flow M control element 2, that is, the non-flow section shielding height Lc, and the throttle section jet flow velocity As is A s / A.
When setting the c ratio to 0.1, it is not very meaningful to make it more than 1001II1, but if the A N / A c ratio becomes very small, for example, about 0°01, the shielding height L
As c increases, the jet flow velocity A1- also increases. That is, the smaller the filling rate of the flow control element 2, the higher the flow velocity ejected from it. Although not shown, the bottom opening 6 of the flow control element 2 is not only covered with a net 8, but also particles with large diameters are filled into the flow control element 2 to increase the void ratio ε.

may be made larger than that of the flowing section, ε.

It is preferable that the particles entering the flow control element 2 be as fine as possible in order to maintain a large void ratio fI.
Instead of 1f18, it is also possible to use a porous plate or a plate with many slits, which allows fluid to enter but prevents particles from entering.

With the above configuration, the driftwood/air introduced into the flow control element 2 is accelerated within the flow control element 2, and the solid fuel is diffused as a powder jet at a much higher speed than the superficial velocity in the layer. The solid fuel is ejected in the desired direction and spreads the solid fuel ejected from the adjacent supply nozzle.

Although the above-mentioned embodiment is an example of a preferred embodiment of the present invention, it is not limited thereto, and various modifications can be made without departing from the gist of the present invention.For example, in this embodiment, a fluidized bed I mentioned the boiler, but it is a waste that is difficult to burn by itself (combustible material is 10 to 10%)
It can be implemented in any type of fluidized bed incinerator in which solid particles are diffused and fed into a fluidized bed, such as in a fluidized bed incinerator in which solid particles containing 20% of the total amount of solid particles are combusted. In this case, dry sludge containing 10 to 20% of combustibles is injected from the supply nozzle 4 of the supply device and diffused and supplied by the shelf surface with the flow control element 2.

(Effects of the Invention) As is clear from the above explanation, the present invention arranges a flow control element that forms a non-flowing part surrounded by hardwood walls in a fluidized bed, and the superficial velocity in the bed is much higher than the superficial velocity in the bed. Since a high-speed @ flow is generated in a direction that prevents the solid particles air-carried in from the supply device from diffusing, the solid particles can be attracted by the high-speed jet flow and uniformly dispersed.

Therefore, the number of installed supply nozzles for supplying solid particles into the fluidized bed can be significantly reduced, and the device structure can be simplified and operation and maintenance management can be facilitated.

For example, according to the arrangement combination example shown in FIG. 6 (A>) during four-way supply, conventionally the space between the coal feeding nozzles 4 is narrowed, and coal particles are ejected between them for diffused supply [see FIG. 6 (A)]. However, in the case of the present invention, the flow control element 2 is disposed near the coal feeding nozzle 4, and the flow control element 2 induces the diffusion of the supplied solid particles with a high-speed jet, so that the feeding The arrangement interval of the charcoal nozzles 4 can be made wider than in the conventional case, and the number of charcoal feeding nozzles per unit area can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram showing an example in which the solid particle supply device for a fluidized bed according to the present invention is implemented as a coal feeding device for a fluidized bed boiler, and FIGS. 2 (A) and (B) each show an example of a flow control element. The central longitudinal cross-sectional view shown in FIG. 2 (C) is the ■-
■ Line cross-sectional view, Figures 3 and 4 are schematic diagrams showing the symbol definitions of the flow control element and its surroundings in the flow analysis model, Figure 5 is a jet flow acceleration characteristic diagram of the flow control element, and Figure 6 is the flow control element. 6(A) is an explanatory diagram showing an example of the arrangement combination of the coal feeding nozzles during four-way feeding, and FIG. 6(B) is a diagram showing the relationship between the coal feeding nozzles arranged in the bed and the flow control element. A conventional coal feeding nozzle, FIG. 6(C) shows an example of the arrangement of the coal feeding nozzle and flow control element of the present invention in the portions surrounded by the primitive lines in FIG. 6(A). 7(A) and 7(B) are perspective views of a coal feeding nozzle, and FIG. 8 is a principle diagram of a fluidized bed boiler having a conventional coal feeding device. 6... Bottom opening, 7... Top opening, A... Opening area of the top opening, Ac... Opening area of the bottom opening.

Claims (1)

[Claims] In the surrounding space a certain distance away from the supply nozzle installation position in the fluidized bed of solid particles that are pneumatically transported by the conveying air, the space ratio is larger than that of the entire fluidized bed, and the bottom opening area A_C and the top opening area are The ratio to the opening area A_N is A
1. A solid particle supply device for a fluidized bed, characterized in that a flow control element is installed that has a relationship of _N/A_C≦1 and has an upper opening facing in a direction in which conveyed solid particles are desired to be diffused.