Blade device for a mixing propeller and the application thereof

Abstract

A blade device for a mixing propeller has a rocking shaft and a plurality of blade units. The blade unit is made of a flexible material and is installed on the rocking shaft via a fixing groove. The blade unit includes a horizontal propelling flexible blade and a vertical uplifting flexible blade. The fixing groove has a horizontal section and a vertical section. One end of the horizontal propelling flexible blade is inserted in the vertical section of the fixing groove while the other end of which is kept free so that it can swing back and forth. One end of the vertical uplifting flexible blade is inserted in the horizontal section of the fixing groove while the other end of which is kept free so that it can swing back and forth.

Claims

1. A blade assembly, comprising: a rocking shaft (1) installed in a vertical direction and a plurality of blade units, each of the plurality of blade units is affixed to the rocking shaft (1) through a fixing groove (2), and each of the plurality of blade units comprises a first flexible blade (3) and a second flexible blade (4), wherein the fixing groove (2) comprises a first vertical section (22), a second vertical section, and a horizontal section (21) connecting the first vertical section (22) and the second vertical section, the second vertical section is affixed to the rocking shaft (1), and wherein one end of the first flexible blade (3) is affixed to the first vertical section (22) and an opposite end of the first flexible blade (3) is not affixed and points away from the rocking shaft (1), and wherein one end of the second flexible blade (4) is affixed to the horizontal section (21) and an opposite end of the second flexible blade (4) is not affixed and points to the vertical direction.

2. The blade assembly of claim 1, wherein the first flexible blade (3) is substantially in a form of an isosceles trapezoid having a long edge and a short edge parallel to each other, wherein the short edge is affixed to the first vertical section (22), and wherein the second flexible blade (4) is substantially in a form of a right trapezoid, whereby an edge connecting two right angles in the right trapezoid is affixed to the horizontal section (21).

3. The blade assembly of claim 2, wherein sizes of two second flexible blades (4) in two adjacent blade units are different by about 10%.

4. The blade assembly of defined in claim 1, where first flexible blades (3) in the plurality of blade units are each identical in size, and second flexible blades (4) in the plurality of blade units each have a different size.

5. The blade assembly of claim 4, wherein the size of each of the second flexible blades (4) in the plurality of blade units arranged in the vertical direction continuously increases.

6. A method for propelling a liquid mixture, comprising: placing the blade assembly of claim 1 in the liquid mixture; oscillating the rocking shaft to cause the plurality of the blade units in the blade assembly to oscillate correspondingly in an angular direction, whereby causing the liquid mixture to flow at a rate lower than 0.25 m/s.

Description

BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS

(1) FIG. 1 structure diagram of the blade device disclosed in the present invention;

(2) FIG. 2 sectional view of the blade device along the A-A axis indicated in FIG. 1;

(3) FIG. 3 structure diagram of the fixing groove disclosed in the present invention;

(4) FIG. 4 principle diagram of the flow state of the liquid mixture generated by the horizontal propelling flexible blade;

(5) FIG. 5 principle diagram of the flow state of the liquid mixture generated by the vertical uplifting flexible blade.

(6) In the drawings: 1. rocking shaft; 2. fixing groove; 21. horizontal section of the fixing groove; 22. vertical section of the fixing groove; 3. horizontal propelling flexible blade; 4. vertical lifting flexible blade.

SPECIFIC EMBODIMENTS

(7) The present invention is further described in more detail in the following specific embodiments with reference to “Attached Drawings of the Description”.

Embodiment 1

(8) As is shown in FIG. 1 and FIG. 2, the blade device for the low-speed mixing propeller comprises a rocking shaft 1 and three fixing grooves 2 secured on the rocking shaft 1. As is shown in FIG. 3, each fixing groove 2 consists of a horizontal section 21 and a vertical section 22. One end of the horizontal propelling flexible blade 3 is inserted in the vertical section 22 of the fixing groove 2, and the other end of the horizontal propelling flexible blade 3 can swing back and forth; one end of the vertical uplifting flexible blade 4 is inserted in the horizontal section 21 of the fixing groove 2, and the other end of the vertical uplifting flexible blade 4 can swing back and forth. During the operation, the horizontal propelling flexible blade 3 can propel the liquid mixture to the pre-set flow rate while the vertical uplifting flexible blade 4 can uplift the liquid mixture so that the activated sludge flocs contained in the liquid mixture are brought upward, which consequently prevents undesirable precipitation of activated sludge flocs in the biopool.

(9) As is shown in FIG. 1, both the horizontal propelling flexible blade 3 and the vertical uplifting flexible blade 4 are designed in a certain form. In accordance with a variety of flow states, the horizontal propelling flexible blade 3 and the vertical uplifting flexible blade 4 can be designed into different forms. In the present embodiment, the horizontal propelling flexible blade 3 is in the form of an isosceles trapezoid, with a longer free end and a shorter fixed end; the vertical uplifting flexible blade 4 is in the form of a right trapezoid whereof the angle between the free end and the fixed end is adjusted to 45°.

(10) As is shown in FIG. 1, the blade device for the low-speed mixing propeller comprises three blade units evenly secured along the long axis of the rocking shaft 1; the size of the three blade units turns increasingly large as they go deeper down from the liquid surface. As the precipitation rate of the activated sludge flocs near the bottom is generally quicker than that near the surface, the size of the vertical uplifting part flexible blade 4 at the lower level is 10% bigger than that at its adjacent place; however, the size of the three horizontal propelling flexible blades 3 is the same. The blade device designed in this way can reach the best mixing effect as the sludge is effectively dispersed and almost no precipitation of flocs can be found.

(11) Place the blade device into the activated sludge channel of a biopool. As is shown in FIG. 4, during the operation, the movement of the blade device leads to bending deformation of the horizontal propelling flexible blade 3 due to the existence of water resistance; the bending deformation of the horizontal propelling flexible blade can then propel the liquid mixture forward diagonally; as a result, the liquid mixture moves forward circuitously as it is repeatedly bounced back by channel walls; this pattern of movement increases the moving distance of the liquid mixture within the channel and consequently extends the retention time of the sewage therein; as is shown in FIG. 5, during the operation, the movement of the blade device also leads to bending deformation of the vertical uplifting flexible blade 4 due to the existence of water resistance; the bending deformation of the vertical uplifting flexible blade can then uplift the liquid mixture; as a result, the activated sludge flocs contained in the liquid mixture are brought upward as well, which effectively prevents precipitation of the sludge and ensures its sufficient mixing with the sewage.

(12) Control the flow rate of the liquid mixture in the biopool around 0.2 m/s; the right-left oscillation of the rocking shaft driven by a motor makes the horizontal propelling flexible blade swing back and forth, which consequently propels the liquid mixture forward diagonally and realizes circuitous movement of the liquid mixture within the channel due to the liquid mixture repeatedly being bounced back by channel walls; the oscillation of the rocking shaft also enables the vertical uplifting flexible blade to lift the liquid mixture upward, which prevents undesirable precipitation of activated sludge flocs. When being adopted in the anaerobic and anoxic zones of the activated sludge process, the rocking shaft is usually driven in the pattern of screw propelling. In a small wastewater treatment system used for pilot-scale test, floating pieces of dead sludge often appear in the liquid mixture due to its low flow rate, a compromise embodied in the design of most systems; however, the adoption of the blade device disclosed in the present invention can significantly decrease the floating pieces of dead sludge, and the denitrification efficiency of the whole process will increase at least 5%.

Embodiment 2

(13) The swinging frequency of the blade device is slowed down so that the impact of lowering down the flow rate on the efficiency of denitrification can be verified. The experiment was conducted using the blade device disclosed in Embodiment 1 and the blade device was also placed in the activated sludge channel of a biopool as was done in Embodiment 1. Control the flow rate of the liquid mixture in the channel around 0.1 m/s, and increase the number of blade devices distributed in the channel accordingly; during the 2 months' experiment, no floating piece of dead sludge was found, besides, the experiment showed even better efficiency in denitrification (the efficiency of denitrification increased at least 10%). However, though the efficiency of pollutant removal will increase when the flow rate of the liquid mixture turns lower, the number of the blade devices distributed in the channel must be increased accordingly, which consequently increases the operational cost. Therefore, the flow rate of the liquid mixture shall not be controlled too low.

(14) It should be understood that the above embodiments are merely to illustrate rather than to limit the present invention. By the same token, what is shown in the attached drawings is only one exemplary embodiment of the present invention, and the structure of the present invention in practical application is not limited to it. Accordingly, any modification or alteration made by the person skilled in the field without departing from the spirit and scope of this disclosure shall fall within the scope of the present invention.