JP2572632Y2 - Axial fan - Google Patents

Description

[Detailed description of the invention]

[0001]

[Industrial application field] The present invention relates to exhaust gas from a coal-fired boiler.
The present invention relates to an axial flow fan installed therein , and more particularly to a variable pitch axial flow fan capable of adjusting the angle of a moving blade attached to an impeller, and more particularly, to preventing a stick between the moving blade and the impeller. Regarding the structure to prevent.

[0002]

2. Description of the Related Art As an axial flow fan, there is a variable pitch axial flow fan capable of changing the angle of a moving blade attached to an impeller in accordance with an air flow rate. For example, such a variable-pitch axial fan is installed for exhaust gas from a coal-fired boiler, and can change the pitch of the moving blades according to the output of the boiler.

[0003]

The conventional variable-pitch axial flow fan, however, was operated in an air flow containing powder and adherent substances because the gap between the rotor blade and the impeller was very small. In the case, for example, as described above, when installed and operated in an exhaust gas containing a large amount of ash, such as a coal-fired boiler, the pitch does not change because the rotor blades and the impeller stick due to the ash attached to the impeller surface, In some cases, it was not possible to adjust the angle of the bucket.

That is, in the conventional variable-pitch axial flow fan, the gap between the rotor blade and the impeller is usually 1 to 1.5 mm.
As a result, the ash adhering to the gap between the moving blade and the impeller is strongly pressed against the surface of the impeller when the moving blade moves and solidifies, and the solidified ash becomes strong and moves the moving blade. As a result, the angle adjustment of the moving blade becomes impossible. And
As a result, it becomes impossible to adjust the exhaust gas amount according to the output of the boiler, and in the worst case, the boiler may have to be stopped.

Further , Japanese Patent Application Laid-Open No. 61-118599 discloses
The described invention relates to dust or dust accumulated on the outer peripheral surface of the impeller.
As the amount of ash increases, the blades become difficult to rotate, and finally the blades
Rotor blades and impellers to prevent this
It suggests increasing the gap between them. But this
According to the invention, when the gap is increased, the blowing of the axial fan
Or the aerodynamic performance deteriorates.
The upper limit of the above clearance is set so that the force performance does not substantially decrease.
The setting is not considered .

The present invention has been made to solve such problems of the prior art, and substantially reduces aerodynamic performance.
To increase the clearance between the rotor blades and the impeller
Installed in the exhaust gas of a coal-fired boiler, which prevents the stick of the rotor blades and the impeller, and allows the rotor blade angle to be adjusted reliably.
It is an object of the present invention to provide an axial flow fan.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a shaft according to the present invention is installed in the exhaust gas of a coal-fired boiler.
The flow fan is mounted on the impeller and adjusts the angle
Have a possible moving blade, with a 3~6mm the gap between the blades and the impeller, as it has a structure in which a-out round notch in the pan near the blades of the blade root is there.

[0008]

According to the experiments performed by the present inventors, the thickness of the ash adhering to the surface of the impeller differs depending on the type of ash, particularly in an axial fan installed in the exhaust gas of a coal-fired boiler. Since the impeller rotates at high speed, when a certain thickness is attached, the thickness does not increase any more, and it is known that the thickness is usually about 3 to 6 mm.

Therefore, as in the above configuration , the gap between the rotor blade and the impeller is set to 3 to 6 mm, which is about the maximum thickness of the deposit (ash) and has a size that does not affect the blowing performance.
And, by providing a round notch near the dish portion of the blade root portion of the rotor blade, the pressing force between the rotor blade and the deposit is reduced, and the deposit on the contact portion escapes from the round notch,
There is no stick between the bucket and the impeller.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. This embodiment is an example in which the present invention is applied to an axial fan provided upstream of an exhaust gas desulfurization device in a coal-fired boiler.

As shown in FIG. 3, a plurality of rotor blades 1 of the axial flow fan are connected to the surface of an impeller 2. Then, the impeller 2 rotates through a shaft 3 connected to a motor (not shown) , and the exhaust gas 4 is discharged from the boiler side by rotating the rotor blade 1 between a casing (outer cylinder) 5 and an inner cylinder 6. It is sent to the chimney side. 7 is a stationary blade,
8 is a shaft sealing part.

Then, as shown in FIG.
To adjust the flow rate of exhaust gas according to the output of the boiler,
By a variable mechanism (not shown) provided on the inner surface of the impeller 2,
The attachment angle can be changed, and the dashed line 1 'indicates the moving blade 1 when the angle is closed to reduce the amount of exhaust air.
The two-dot chain line 1 "shows the state of the moving blade 1 when the exhaust air amount is increased by opening the angle, during which the angle of the moving blade 1 can be changed.

The axial fan provided on the upstream side of the flue gas desulfurization device of the coal-fired boiler has a temperature of 80 to 100.
At 0 ° C., it has some water, and the ash in the exhaust gas 4 adheres to each part of the axial flow fan.

[0014] Then, as described above, although the surface of the impeller 2 is attached ash a thickness of about 3 to 6 mm, the moving blade 1 and the impeller 2
Of conventional gap between it was about 1~1.5mm with
The ash deposited in the gap between the moving blade 1 and the impeller 2 is moving blade 2
When the blade moves, it is strongly pressed against the surface of the impeller 2 and solidifies. When the solidified ash becomes strong, the rotor blade 1 stops moving, and it becomes impossible to adjust the amount of exhaust gas according to the output of the boiler. Had to stop the boiler.

Therefore, according to the present invention, as shown in FIGS. 1 and 2, the gap 9 between the moving blade 1 and the impeller 2 is about the maximum thickness of the deposit (ash) and affects the air blowing performance. A rotor blade 1 having a width of 3 to 6 mm, which is not large enough, and fitted to the impeller 2
By providing a round notch 10 in the blade root near the dish 1A, the pressing force between the moving blade 1 and the deposit is reduced,
As the attached matter of the contact part escapes from the notch 10,
A stick is not formed between the rotor blade 1 and the impeller 2.

[0016]

[Effects of the Invention] As described above, according to the present invention , a coal-fired boiler capable of adjusting the angle of a moving blade attached to an impeller.
In the axial flow fan installed in the exhaust gas, the gap between the moving blade and the impeller is set to 3 to 6 mm, and a round notch is provided in the vicinity of a plate portion of the blade root of the moving blade, so that Since the stick between the wing and the impeller can be prevented, the angle of the moving blade can be surely adjusted, and the effect that the moving blade angle can be safely adjusted according to the amount of exhaust air is exhibited.

[Brief description of the drawings]

FIG. 1 shows an embodiment of an axial fan according to the present invention.
It is sectional drawing of the connection part of a rotor blade and an impeller.

FIG. 2 is a view showing a moving blade in FIG. 1;

FIG. 3 is a cross-sectional view showing a main part of an axial fan provided upstream of a flue gas desulfurization device of a coal-fired boiler.

FIG. 4 is a view for explaining angle adjustment of a moving blade in FIG. 3;

[Description of Signs] 1 ... rotor blade, 1A ... dish portion, 2 ... impeller, 9
… Gap between rotor blade and impeller, 10… notch.

Claims (1)

(57) [Scope of request for utility model registration] An axial fan installed in exhaust gas of a coal-fired boiler , comprising: an impeller;
Has an adjustable blades of axial fan with a 3~6mm the gap between the blades and the impeller, in which a-out round notch in the pan near the blades of the blade root .