JPH07151308A - Fluidizing air injector - Google Patents

Abstract

PURPOSE:To prevent the blockading from occurrings in a fluidizing air injector, employed for a fluidized bed boiler and the like, due to the reverse flow of fluidizing material. CONSTITUTION:The flow direction of combustion air 21a is designed so as to be vertically upward in an initial introducing pipeline 22, then, the direction is converted into downward direction and resistance bodies such as perforated plates 26, 27, 28 and the like are provided in a downward flow passage 25 while an injection port 25a is opened at the side of an injection port 25a at the lower end of the downward flow passage 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in fluidizing air injectors used in fluidized bed heating furnaces, fluidized bed boilers, fluidized bed reactors and the like.

[0002]

2. Description of the Related Art For example, when performing combustion using a fluidized bed, a predetermined amount of particles (referred to as a fluid material) is charged into a fluidized bed combustion device (in a vertical tower) and stored, and from below When the gas is aerated and the flow rate is increased, the particles are blown up, the space between the particles is enlarged, and the particles fall again. When the air flow rate is further increased, the vertical movement of the particles becomes more intense,
Around the numerous bubbles, particles flow down to fill the traces of the bubbles to form a fluidized bed.

Since this fluidized bed has a uniform internal temperature and a large heat transfer coefficient, it is effective as a uniform heating method without local heat loss by inserting and mounting a heating body such as various reaction tubes in the bed. .

FIG. 7 is a conceptual diagram showing an example of a conventional combustion furnace using a fluidized bed. In this figure, the combustion furnace (91)
A fluid material (92) is previously charged in the inside of the fluid material (92), and a heating medium (9) in which a heating medium is flowing is provided.
3) etc. are inserted and mounted. Combustion air is sent from the blower (94) to the air pipe (95) and the plenum chamber (9).
6) and the perforated plate (97) to be fed into the combustion furnace (91) to form a fluidized bed.

On the other hand, by burning oil fuel or the like in the high temperature gas generation furnace (98) and introducing the generated high temperature gas into the fluidized bed through the plenum chamber (96) or directly, the fluid material (92) is coal or the like. After heating above the ignition temperature of the fuel, the solid fuel such as coal in the fuel storage hopper (99a) is supplied into the fluid material (92) through the supply device (99b) and the supply pipe (99c). Then, spontaneous combustion starts and the fluid material (92) is further heated by the combustion heat, so that the supply of the high temperature gas from the high temperature gas generating furnace (98) is stopped.

In this state, the calorific value of the fuel and the heat transfer tube (93)
By adjusting the heat absorption amount of the fluidized bed, the fluidized bed proper temperature at which combustion ash remaining in the fluidized bed and melting of the fluid material do not occur is maintained. The combustion exhaust gas is discharged to the outside of the system through the freeboard (91a), the exhaust gas duct (100) and the dust collector (101).

The perforated plate (97) for feeding the combustion air from the plenum chamber (96) to the fluidized bed has a high strength, a low manufacturing cost, and a high cost when the diameter of the combustion furnace (91) is large.
Alternatively, since there is a limit in terms of maintenance, in that case, a plenum chamber ceiling plate is provided at a position where the perforated plate (97) is arranged, and a plurality of air injectors are appropriately arranged on the ceiling plate to prevent the perforated plate (97). ) Has the same function as.
FIG. 8 is a vertical cross-sectional side view showing an example of such an air injector, in which combustion air (21
The a) is jetted into the fluid material (92) through the air introduction pipe (22) and the jet hole (24) to form a fluidized bed. (2
3) is a plenum chamber ceiling plate.

[0008]

As described above, due to the combustion air sent from the perforated plate or the air injector into the fluidized material, the fluidized material is fluidized while performing complicated movement including vertical movement. . Here, as a simple model, if air bubbles are generated in the fluid material having an average height of H and the fluidized bed is raised by ΔH, the weight of the fluid material and the pressure applied to the perforated plate or the air injector are increased. . When the bubble breaks from this state at the upper part, the gas in the bubble is released to the freeboard, and the pressure of the freeboard rises slightly. On the other hand, if the ceiling of the bubbles in the fluid material breaks and the pressure inside the bubbles escapes,
The pressure (force) applied downward from the position where the bubbles were present decreases. Further, the fluid material in the surroundings flows into and fills the traces from which the bubbles have escaped, and the pressure in the fluid material begins to rise again. At this time, the height of the fluidized bed is reduced and the pressure is slightly lowered.

As described above, when the pressure fluctuation occurs in the fluidized bed due to the increase and decrease of the pressure and the pressure fluctuation width is larger than the pressure (dynamic pressure) of the air sent from the perforated plate or the air injector, The fluid material repeatedly flows backward through the perforated plate or the injection hole of the air injector, though within a short time, and flows into and deposits in the plenum chamber, eventually leading to blockage. Therefore, the amount of combustion air to be fed is reduced and eventually stops. Along with this, fluidization of the fluid material deteriorates and stops, and the fluidized bed combustion device becomes inoperable.

[0010]

In order to solve the above-mentioned conventional problems, the present invention is directed to a fluidizing air injector used in a fluidized bed apparatus formed of solid particles and a gas, in a vertically upward direction. An inlet pipe through which air flows, a downward flow passage that is inverted at the upper end of the inlet pipe and vertically flows downward, an ejection hole that opens laterally at the lower end of the downward passage, and the downward flow passage The present invention proposes a fluidizing air injector characterized by including a resistor provided therein.

[0011]

In the fluidizing air injector of the present invention, an introduction pipe line in which air flows vertically upward, and a downward flow passage in which the air flows vertically downward by reversing at the upper end of the introduction pipe line,
Since it has a jet hole that opens to the side at the lower end of the downward flow path, even if the fluid material flows into the air flow path due to pressure fluctuations in the fluidized bed, the downward flow path is reversed. Since it flows in the (upward) direction and the resistor is provided in the flow path, the fluctuating pressure is consumed by the pressure loss when passing through the fluid material. Therefore, the fluid material does not reach the inversion position at the upper end of the downward flow path and enter the introduction conduit.

[0012]

1 is a vertical sectional side view showing a first embodiment of the present invention, and FIG. 2 is a horizontal sectional view taken along the line II--II of FIG. In these figures, the same parts as those of the conventional one described with reference to FIG. 8 are designated by the same reference numerals to avoid redundancy and the description thereof is omitted.

The combustion air (21a) flows vertically upward in the introduction pipe (22), passes through a plurality of small holes (22a) provided around the upper end of the introduction pipe (22), and an outer cylinder (25). Into the annular cross-section flow path between the inlet and the inlet pipe (22). On the other hand, a plurality of stages of perforated plates (26), (27), (2
8) are arranged, and the small holes (26a), (27
A) and (28a) are staggered with respect to each other. Combustion air flows downward in the annular cross-section flow path through the small holes (26a), (26b), (27a), and is provided around the outer cylinder (25) at the lower end of the annular cross-section flow path. Further, it is jetted into the lateral fluid material (92) through a plurality of jet holes (25a) to form a fluidized bed.

In this embodiment, as long as the combustion air (21a) is ejected from the ejection hole (25a), the surrounding fluid material does not flow in through the ejection hole (25a), and even if it flows in. Also, it is only deposited on the portion indicated by reference numeral (29) in the figure in a shape corresponding to the repose angle of the fluid material.

On the other hand, when the pressure fluctuation occurs in the fluidized bed and the negative pressure due to the fluctuation width is large, the fluid material flows backward through the ejection hole (25a) though it is for a short time. In this case, since the volume and the passage area are large at the place where the fluid material particles enter, the flow velocity at the time of the reverse flow becomes rapid. Further, the fluid material particles that have flowed in become an upward flow, and the perforated plates (28), (27),
Although it will pass through the small holes (28a), (27b), (26a) of (26), the number of steps of the perforated plate, the shape of the small holes, and the number of the small holes are such that the fluctuating pressure is small holes (26a), (27a). ), (28a) is selected so as to be consumed by the resistance, that is, the pressure loss when the fluid material passes through, and the fluid material itself has a plurality of small holes (22
It moves to the height of a) and passes through its small hole (22a) and the introduction pipe (2
2) It will not flow into the inside, so the introduction pipe (2
2) It is possible to prevent the lower part from being blocked by the fluid material.

The fluid flowing upward from the small holes (28a), (27a) and (26a) is perforated plates (28), (27) and (2).
6) A stable and constant shape corresponding to the angle of repose is deposited on the upper surface, and a fixed amount is deposited without closing the small holes. If the amount exceeds a certain amount, it will flow down from the small holes (28a), (27a), (26a) to close the small holes, so a powder sealing effect that prevents the flow of fluid material from below will be created. It is desired to cause the fluid material to reach the small hole (22a) portion by promoting the synergistic effect that occurs and increases the pressure loss in that portion.

Further, when the pressurization due to the pressure fluctuation is eliminated, the air originally sent to the injector flows, so the invading particles are discharged outside the injector together with this air flow. Therefore, the time when the fluid material particles flow back into the nozzle is instantaneous, and the particles accumulated in the injector are limited to a small amount, so that clogging of the outer cylinder (25) by the fluid material particles is also avoided. As a result, a steady fluidized bed situation is established.

Next, FIG. 3 is a vertical sectional side view showing a second embodiment of the present invention, and FIG. 4 is a horizontal sectional view taken along the line IV-IV of FIG. 5 is a vertical sectional side view showing a third embodiment of the present invention, and FIG.
6 is a horizontal sectional view taken along line VI-VI of FIG. Also in these drawings, the same parts as those described above are designated by the same reference numerals, and detailed description thereof will be omitted.

[0019]

According to the present invention, the flow direction of the combustion air is vertically upward in the introducing pipe and then inverted to downward, and a resistor is provided in the flow passage, so that the pressure fluctuation in the fluidized bed is caused. The amount of the flowing material and the arrival position of the flowing material are restricted by the negative pressure caused by, and the flowing back of the flowing material is suppressed. Therefore, complete obstruction of the injector can be prevented and stable fluidized bed combustion can be continued.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a first embodiment of the present invention.

FIG. 2 is a horizontal sectional view taken along the line II-II of FIG.

FIG. 3 is a vertical sectional side view showing a second embodiment of the present invention.

FIG. 4 is a horizontal sectional view taken along the line IV-IV in FIG.

FIG. 5 is a vertical sectional side view showing a third embodiment of the present invention.

6 is a horizontal sectional view taken along the line VI-VI of FIG.

FIG. 7 is a conceptual diagram showing an example of a conventional fluidized bed combustion method.

FIG. 8 is a vertical sectional side view showing an example of a conventional fluidizing air injector.

[Explanation of symbols]

 (21a) Combustion air (22) Inlet pipe (22a) Small hole (23) Plenum chamber ceiling plate (24) Jet hole (25) Outer cylinder (25a) Jet hole (26), (27), (28) Porous Plates (26a), (27b), (28a) Small holes (29) Accumulation part (91) Combustion furnace (91a) Free boat (92) Fluid material (93) Heat transfer tube (94) Blower (95) Air tube (96) ) Plenum chamber (97) Perforated plate (98) High temperature gas generator (99a) Fuel storage hopper (99b) Feeder (99c) Supply pipe (100) Exhaust gas duct (101) Dust collector

Claims (1)

[Claims] 1. A fluidizing air injector used in a fluidized bed apparatus formed of solid particles and gas, wherein an inlet pipe line in which air flows vertically upward and an upper end of the inlet pipe line are reversed. Fluidization characterized by comprising a downward flow passage in which the air flows vertically downward, an ejection hole that opens laterally at the lower end of the downward flow passage, and a resistor provided in the downward flow passage. Air injector.