Patent Application
20160067658
The present invention relates to devices for wastewater treatment, specifically to a blade device and its application in the mixing propeller that is used for treating the low-speed liquid mixture.
Currently, in the field of wastewater treatment, submersible mixers are widely utilized in both China and most of other countries for industrialized-scale treatment of liquid mixture. The blades designed for these submersible mixers are all made of rigid material. As drive motors of these submersible mixers were installed below the liquid surface, the designing and manufacturing processes of these mixers require sophisticated techniques. Besides, once being manufactured out, these mixers are usually considerably huge. As to those experimental-use small mixers, like those designed out of the same principles for industrialized production, they also present a variety of shortcomings such as inconvenience for being placed in the channel of a biopool, inducing undesirable flow states, high manufacturing cost, vulnerability to damage and difficulty for maintenance. Therefore, they are not suitable for being used in the wastewater treatment that requires long operational duration and high stability.
With increasing demand in municipal sewage treatment and increasingly strict standards on effluent discharge, more and more efforts, financially and scientifically, have been taken to realize up-standard discharge of municipal sewage. Therefore, the research and development of small-sized, high-efficient devices for wastewater treatment are of great market potential.
Chinese Patent CN 203155141U (date of authorization: 2013 Aug. 28) disclosed a blade device used on a precipitated-silica pulping machine. The blade device comprises two mutually symmetric components that are bolted on the main shaft via a connecting plate. Each component bears two identical blade units that are 90-degree connected to each other through a base plate, and four blade units of the two components constitute the whole blade-containing mixing system. Each blade unit consists of a horizontal blade and a vertical blade, and both the horizontal and vertical blades are in serrated form. When being adopted for pulping precipitated silica, this blade device presents some advantages such as good shearing effect, short pulping time and low energy consumption. However, it has some disadvantages as well. For example, both horizontal and vertical blades of the blade device are installed at fixed places and are made of rigid material, which make the whole blade device, apart from desirable shearing force and mixing effect, generates no forward-going and uplifting force. Therefore, the blade device disclosed in this cited invention shows poor effect in propelling the liquid mixture upward.
The present invention discloses a blade device for the mixing propeller and its application so that the shortcomings, such as high technical demand in manufacturing process, big body volume and undesirable quick flow rate presented in the prior art can be effectively overcome. This blade device can circuitously propel and uplifting the liquid mixture at the same time, which consequently extends the retention time of the sewage in the biopool and prevents precipitation of activated sludge flocs. It also enjoys such advantages as being simple in structure, stable during operation and easy for maintenance.
The following technical solutions are adopted to materialize the objective of the present invention.
A blade device for the mixing propeller, comprising a rocking shaft and a plurality of blade units, the said blade units are made of flexible material and are installed on the rocking shaft by means of the fixing groove;
the said flexible blade unite consists of a horizontal propelling flexible blade and a vertical uplifting flexible blade, and the said fixing groove consists of a horizontal section and a vertical section; one end of the said 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 said 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.
Preferably, the said horizontal propelling flexible blade is in the form of an isosceles trapezoid, with a longer free end and a short fixed end; the said vertical uplifting flexible blade is also in the form of a trapezoid whereof the angle between the free end and the fixed end is an acute one.
Preferably, the said horizontal propelling flexible blade and the vertical uplifting flexible blade constitute a blade unit; there are a plurality of blade units evenly secured along the long axis of the rocking shaft; the deeper down from the liquid surface, the bigger the size of blade units is.
The application of a blade device for the mixing propeller, wherein the said blade device for the mixing propeller is applied to propel and mix the liquid mixture at the flow rate lower than 0.25 m/s.
In contrast with the prior art, the beneficial effects of the technical solutions disclosed in the present invention include:
(1) Unlike the screw propeller adopted in the prior art, which relies on the relative movement between the shaft and the drive motor, a design consequently leads to such problems as mechanical abrasion, liquid leakage and corrosion, the blade device disclosed in the present invention, due to the fact that all the components below the liquid surface are completely fixed, demonstrates many advantages such as being convenient for anticorrosive processing, simple in structure, stable during operation, easy for maintenance and low in manufacture cost;
(2) the horizontal propelling flexible blade exerts forward-going propelling effect to the liquid mixture due to the fact that one end of the said horizontal propelling flexible blade is inserted in the vertical section of the fixing groove and the other end of which is kept free so that it can swing back and forth; meanwhile the vertical uplifting flexible blade exerts uplifting effect to the liquid mixture due to the fact that one end of the said vertical uplifting flexible blade is inserted in the horizontal section of the fixing groove and the other end of which is kept free so that it can swing back and forth; such a design enables the blade device to present both propelling and uplifting functions to the liquid mixture; working under the low flow rate, the blade device disclosed in the present invention can effectively prevent precipitation of activated sludge flocs in the biopool; it is particularly suitable for realizing desirable flow state of the liquid mixture within small-sized channels.
(3) the horizontal propelling flexible blade disclosed in the present invention is in the form of an isosceles trapezoid, with a longer free end and a short fixed end; as the linear speed at the fixed end is slow whereas that at the free end is quick, the best propelling effect can be realized with the limited size of the flexible blade;
the vertical uplifting flexible blade is also in the form of a trapezoid whereof the angle between the free end and the fixed end is an acute one; as the linear speed increases proportionally with the increase of the distance away from the rocking shaft, the decrease of the impact size of the flexible blade can effectively keep the flexible blade in a desirable bending state, which consequently presents a desirable uplifting effect;
(4) the activated sludge flocs tend to precipitate, however, the plurality of blade units of the device disclosed in the present invention can provide not only continuous uplifting force for the flocs, but also forward-going propelling force at the cross section of the channel; meanwhile, the comparatively larger size of the flexible blade that is deeper down from the liquid surface can effectively prevent precipitation of flocs at the bottom of the biopool;
(5) in order to prevent precipitation of activated sludge flocs, the flow rate of the liquid mixture shall be kept at 0.25 m/s or above; however, a lower flow rate can increase the hydraulic retention time of the sewage in the channel, which consequently improves the removal efficiency of pollutants; the blade device for the mixing propeller disclosed in the present invention provides a desirable solution for realizing effective propelling and mixing functions (therefore preventing precipitation of flocs) at the flow rate lower than 0.25 m/s (“Specification for Design of Oxidation Ditch” compiled by the China Association for Engineering Construction Standardization stipulates that the flow rate of the liquid in the oxidation ditch shall not lower than 0.25 m/s.)
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.
The present invention is further described in more detail in the following specific embodiments with reference to “Attached Drawings of the Description”.
As is shown in
As is shown in
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Place the blade device into the activated sludge channel of a biopool. As is shown in
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%.
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 said 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.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201310620918.1 | Nov 2013 | CN | national |
