JPS5852686B2 - Mandarin Congouriyu Haneguruma - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improved low speed impeller for a mechanical aeration system.

Impellers are often designed to produce axial or radial liquid flow, an example of the latter being a centrifugal impeller.

When the discharge flow is a mixed flow of axial and radial directions, it is called a mixed flow impeller.

The impeller has a number of vanes extending from a boss attached to a supporting and rotating shaft.

In the case of large impellers, the efficiency of the vanes is generally improved by providing a shroud in the central space that guides the liquid flow around or through the boss.

Of course, the boss and the shroud may be of an integral structure.

Each blade of the impeller is attached to a boss or constructed with an edge including the point where it contacts the shroud.

The other edges of the vanes are in three parts, commonly referred to as the leading edge, the suction side edge and the discharge side edge, in relation to the rotation of the impeller and the direction of liquid flow.

Other design factors for the impeller include impeller balance,
There are issues such as what is the best shape for manufacturing, and what to do when strings or pieces of cloth get wrapped around the blades.

Providing impellers on the water surface is a widely used method for aerating and biologically treating wastewater and industrial waste.

The impeller is typically fixed to the lower end of the vertical output shaft of a motor with a reduction gear set supported on a float or fixed structure.

High-speed aeration systems often include an axial impeller mounted on a vertical suction tube having an upper member that deflects wastewater according to a generally circular pattern with near-vertical sections.

Regarding the amount of wastewater sucked and discharged per horsepower, that is, per unit current consumption, high-speed aeration equipment is low in efficiency despite its high equipment cost.

Low speed aerators are driven by electric motors or engines of less than 175 HP and are generally classified into two types.

One type aerates a large amount of wastewater by stirring it close to the water surface, and the second type aerates the wastewater near the bottom of the tank, starting well from the bottom of the tank. It sucks in a large amount of wastewater and discharges it horizontally, creating a strong stream of water that passes through the water surface and toward the walls of the aquarium.

When a suction type aeration device is used in a fixed structure tank, a large suction pipe with an inlet near the bottom of the treatment tank is required.

Such aerators typically use axial impellers, and the discharge stream has a vertical component similar to that of high-speed aerators.

Open-type impellers without suction pipes have a simple structure and are suitable for use, but many open-type impellers are currently considered to be suction types, but these are 10ft (approx. .03
7? At depths greater than Z), efficiency decreases slightly.

The efficiency of this type of impeller changes significantly when its position relative to the water surface changes slightly.

This specification deals with two factors: suction/drainage capacity and immersion range, and these two factors are important when designing a sewage or wastewater treatment tank, when the aeration unit is mounted on a float and when it is mounted on a bridge-like support. It has a slightly different meaning compared to when it is installed.

(In the case of sewage or wastewater treatment tanks, the flow rate of water flowing through the tank and the water level represent the water level above the surface of the following equation).

The above equation shows that when the length of the weir is constant, the water level rises and falls as the flow rate Q increases and decreases.

This relationship means that for a standard sewage treatment tank with a fixed surface aeration system, the impeller is deeply immersed and operates at maximum capacity during the day when the flow rate is high, and at night when the flow rate is significantly reduced, the water level It is used to operate at a lower capacity by lowering the immersion depth of the impeller.

This natural regulation method is extremely advantageous for biological purification processes of organic matter that utilize supplied oxygen.

Furthermore, it is obvious that in the case of a small flow rate, the amount of power required is reduced due to the reduction in suction/discharge efficiency and capacity, so that the power cost is saved.

However, conventional impellers have the drawback of large fluctuations in suction and discharge capacity for small immersion ranges.

This means that in order to maintain the water level within the narrow range that the impeller can manage, the outlet weir must be of such a length that it is almost impossible to do so from the perspective of the overall design of the treatment tank. .

Mechanically operated outlet weirs were sometimes used to maintain a constant water level.

Such a structure complicates the wastewater treatment equipment, negates the use of maintenance-free low-speed aeration equipment, and also eliminates some of the advantages of the natural regulation method described above for maintaining a constant water level.

In addition, conventional wastewater treatment equipment is designed to operate for long periods of time in a more or less constant state, and for this purpose, a low-speed aeration device is installed on a float that is supported at a constant height relative to the water level. There are also examples.

Such floats need to be designed to properly support each aeration device and to hold the aeration device stably against the downward reaction force of suction and discharge.

The sucking and pumping action is always accompanied by some pulsation, and the aeration unit as a result rocks up and down in the water.

Some unit aerators of the aeration unit are displaced up and down due to unpredictable slight interactions.

If several aeration devices are displaced downwards all at once, the current consumption will increase sharply, and the power supply may be overloaded and the circuit breaker may trip.

Such a situation is particularly likely to occur when starting or stopping some aeration units.

Regarding the characteristics of the impeller, an impeller that applies an excessive torque load to the motor when the impeller is slightly displaced downward in water inevitably has such instability.

It is therefore an object of the present invention to provide a highly stable impeller having the desired suction and removal capacity and immersion range required in standard biological treatment tanks utilizing surface aeration.

The impeller according to the invention has an inverted conical shroud having a base angle of 45° and extending downwardly from the shroud such that its suction side edge is located substantially below the conical apex angle of the shroud. It is equipped with 3 to 5 blades.

The included angle between the leading edge of each blade and the impeller shaft is on the order of 300 degrees, and the total height of the impeller is on the order of 2/3 of its diameter.

The main feature of the impeller according to the invention is the wide range of immersion limits for the standard operating range.

The treatment tank 8 shown in FIGS. 1 and 2 includes an inlet pipe 9 with a baffle plate attached to the front, and an outlet weir 10 for controlling the water level in the treatment tank 8.

A tub 11 is provided on one of the four side walls of the treatment tank 80 over the entire length of the outlet weir 10, and a drain pipe 12 is provided in the tub 11.
is the installation.

The mechanical aeration device 13 is installed on the beam-shaped support 1 in the center of the treatment tank 8.
4, which includes an upper drive motor 15, a reduction gearing 16, and a support 14 extending downwardly from the reduction gearing 16.
It has an output shaft 17 extending toward the bottom of the processing tank 8, and an impeller 21 attached to the lower end of the output shaft 17 so as to rotate together with the output shaft 17 above the water surface of the processing tank 8.

The impeller 21 consists of a shroud 22, several blades 23, and a boss (not shown in detail), and is removably fixed to the output shaft 17 by the boss.

The bubble and shroud 22 may be any suitable structure known in the art.

One feature of the invention is that the vane 23 has the shape of a flat plate and is fixed directly to the shroud 22 at its inner edge, for example by welding.

The shroud 22 has an inverted cone shape with a base angle of 45°, and the edge 2
It has a circular upper surface defined by 2a.

The total height of the shroud 22 from the lower apex 22b to the upper end of the cone is therefore equal to the radius of the edge 22a.

For practical purposes, the shroud 22 has a frustoconical shape as shown, and has a small circular lower end surface 22c.

The inner edges of each blade 23 are as described above, but the other outer edges are the front edge 25 and the inner and outer sides of the suction side, as shown in FIGS. Edge portion 26a
, 26b and the discharge side edge 27.

The blade 23 is approximately 30 degrees from the downward extension of the axis of the output shaft 17.
and are equiangularly disposed about the axis.

The blade 230 plane and the axis of the impeller 21 intersect with the upper surface of the shroud 22 at an angle of 600°.

The leading edge 25 of each vane 23 extends downwardly from its reference point to approximately 0.3R below the conical apex 22b.

The edge 27 on the discharge side extends from the edge 22a of the shroud 22 by a vertical distance approximately equal to the radius R, and extends from the edge 22a of the shroud 22 to the apex 22b of the cone.
It has reached a level of height.

The suction side edge 26a also extends horizontally at the front edge 25 at the height level of the apex 22b, and the suction side edge 26b is
From there, it further reaches the lower end of the discharge side edge 27 mentioned above.

The basic shape of the blades 23 has been described above, but in reality, the outer shape of the blades 23 can be made into an appropriate shape such as a curved shape or a curved shape so that the efficiency of the impeller is improved even a little.

Furthermore, as shown in FIG.
3 may be provided.

That is, as shown in the figure, the leading edge 25a is connected to the blade 2.
The triangular region 31 may be formed so as to have a slight rake angle in the direction of rotation.

In addition, if it is desired to increase the capacity of the impeller to some extent under the predetermined design conditions of the impeller, the discharge side edge 27a may be extended outward by 1.2R.
The trailing edge 32 may be formed to extend by a distance corresponding to .

This distance may be greater than 1.2R, but 1.5R
shall not be significantly exceeded.

The number of blades 23 of the impeller 210 may be four or five.

However, since the blades 23 are provided around the shroud 220 over an angle of 90° or more, it is not good to provide six or more blades 23 because the blades will overlap excessively.

As mentioned above, ordinary aquariums, ponds, swamps, etc. are large in size.
It is necessary to install quite a number of aeration devices at equal intervals.

Treatment vessel 8 may be considered a standard biological treatment vessel as a single unit.

The processing tank 8 is 80ft x 80ft x 20ft (approximately 2
4.24mx 24.24? ? ZX 6.06? ? Z)
So, the height of weir 10 is 18ft (approximately 5.454771)
It is.

In the case of standard wastewater, the standard allowable flow rate Q of the treatment tank 8 is 7 per minute.
It is on the order of 500 gallons (approximately 28,387.5 feet),
The minimum and maximum flow rates are 2,500 gallons (approximately 9,462.5 feet) and 22,000 gallons (approximately 8,327 gallons) per minute, respectively.
0 standing).

For these flow rates, the water level above the weir 10 is calculated as shown in the following table using the above-mentioned formula.

As can be seen from the above table, according to the impeller of the present invention, the weir 1
0 is only 29ft long due to its immersion range.
79crn).

If a conventional impeller is installed in the same treatment tank 8, the weir 1
0 length is 80ft (approximately 24.0477Z) to 12
It needs to be 0ft (approximately 36.367?Z).

The weir 10 is a particularly inexpensive device, but if it is made this long, the tub 11 is connected to the treatment tank 8, as indicated by the broken line in FIG.
The processing equipment will become significantly more complicated.

As described above, according to the present invention, the impeller has the above structure, and in particular, the outer peripheral edge of each blade is formed by the front edge 25, the inner and outer suction side edges 26a and 26b, and the discharge side edge 27. As a result, the length of the weir 10 can be significantly shortened as a result of the desired suction and drainage ability being obtained over a wide operating immersion range.

In addition, there is no need to install a float that supports the impeller at a constant height relative to the water level, and even if the impeller is slightly displaced downward in the water, an excessive torque load will occur and the power circuit will be cut off. The operation becomes stable.

Furthermore, each blade is easy to manufacture because it is only necessary to form a flat plate and fix it to the shroud.

[Brief explanation of the drawing]

Figure 1 shows an example of a biological treatment tank in which an aeration device is attached to a bridge-type support, with some sections showing an elevational view, and Figure 2 a top view of the treatment tank shown in Figure 1. Figure 3 is a bottom view of the impeller with the output shaft in cross section and the outline of the shroud shown in broken lines; Figure 4 is a partial side view of the impeller in Figure 3;
FIG. 5 is a side view of the impeller seen from the direction of line 5--5 in FIG. 3, and FIG. 6 is an explanatory diagram showing a blade having a different shape at the peripheral edge. 8... Processing tank, 9... Inlet pipe, 10.
...Exit weir, 11...Pail, 12...
... Drain pipe, 13 ... Mechanical aeration device, 14
...Beam-shaped support, 15 ... Upper drive motor, 16 ... Reduction gear device, 17 ...
・Output shaft, 21... Impeller, 22...
Shrouding plate, 23...Blade, 22a...Shrouding plate top surface, 25...Front edge of 22, 26a,
26b...22's radially inner and outer portions of the suction side edges, 27...22's discharge side edges.

Claims (1)

[Claims] 1. 1 drive motor having a vertical output shaft extending downward, an impeller fixed to the lower end of the output shaft and having a lower inflow end, the upper end of the impeller being lower than the liquid level. A liquid aeration mixing device comprising means for supporting a drive motor a predetermined distance higher and with its lower end at a predetermined immersion level, wherein said impeller comprises an inverted conical shroud of height R and three to five flat shrouds. The upper end of the shrouding plate forms the upper end of a circular impeller with a radius R, and each blade is in the shape of a flat plate, and the upper end of the shrouding plate forms the upper end of a circular impeller with a radius of R. It has a rake angle and is arranged so that the inclined surface intersects the axis of the impeller at the upper end of the impeller, and the outer peripheral edge of each blade has a trailing edge that continues to the shroud, a leading edge 25, and an inner suction side edge. Part 2
6a, an outer suction side edge 26b, and a discharge side edge 27, the leading edge of each vane extending radially outwardly and downwardly from the shroud and continuing to the suction side edge; The discharge side edge of each vane has a height R and a radius of IR~1.5R and extends from the outer suction side edge to the upper outer edge of the shroud, and the inner suction side edge of each vane is connected to the shroud. A 0-vertical merging impeller for a mechanical liquid level aeration device, characterized in that the impeller is located approximately 0.3R below the lower end and forms the lower end of the impeller. 2. The impeller according to claim 1, wherein the leading edge of each blade has a slight rake angle radially rearward. 3. The impeller according to claim 1, wherein the lower surface of the shrouding plate is truncated. 4 The upper end of the impeller is 0.25R- lower than the liquid level.
Claim 1, wherein the support means supports the drive motor so as to be located above 0.2R.
The impeller described in section.